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Building-Integrated Photovoltaic Designs for Commercial and Institutional Structures A Sourcebook for Architects Patrina Eiffert, Ph.D. Gregory J. Kiss

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Page 1: Building-Integrated Photovoltaic Desings for · PDF fileBuilding-Integrated Photovoltaic Designs for Commercial and Institutional Structures ASourcebook for Architects Patrina Eiffert,

Building-Integrated PhotovoltaicDesigns for Commercial andInstitutional Structures

A Sourcebook for ArchitectsPatrina Eiffert, Ph.D.Gregory J. Kiss

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AcknowledgementsBuilding-Integrated Photovoltaics for Commercial and Institutional Structures: ASourcebook for Architects and Engineers was prepared for the U.S. Department ofEnergy's (DOE's) Office of Power Technologies, Photovoltaics Division, and theFederal Energy Management Program. It was written by Patrina Eiffert, Ph.D., of the Deployment Facilitation Center at DOE�s National Renewable EnergyLaboratory (NREL) and Gregory J. Kiss of Kiss + Cathcart Architects.

The authors would like to acknowledge the valuable contributions of SheilaHayter, P.E., Andy Walker, Ph.D., P.E., and Jeff Wiechman of NREL, and AnneSprunt Crawley, Dru Crawley, Robert Hassett, Robert Martin, and Jim Rannels ofDOE. They would also like to thank all those who provided the detailed designbriefs, including Melinda Humphry Becker of the Smithsonian Institution, Stephen Meder of the University of Hawaii, John Goldsmith of Pilkington SolarInternational, Bob Parkins of the Western Area Power Administration, SteveCoonen of Atlantis, Dan Shugar of Powerlight Co., Stephen Strong and BevanWalker of Solar Design Associates, Captain Michael K. Loose, CommandingOfficer, Navy Public Works Center at Pearl Harbor, Art Seki of Hawaiian ElectricCo., Roman Piaskoski of the U.S. General Services Administration, Neall Digert,Ph.D., of Architectural Energy Corporation, and Moneer Azzam of ASE Americas,Inc.

In addition, the authors would like to thank Tony Schoen, Deo Prasad, PeterToggweiler, Henrik Sorensen, and all the other international experts from theInternational Energy Agency�s PV Power Systems Program, TASK VII, for theirsupport and contributions.

Thanks also are due to staff members of Kiss + Cathcart and NREL for their assistance in preparing this report. In particular, we would like to acknowledge the contributions of Petia Morozov and Kimbro Frutiger of Kiss + Cathcart, andRiley McManus, student intern, Paula Pitchford, and Susan Sczepanski of NREL.

On the cover: Architect�s rendering of the HEW Customer Center in Hamburg, Germany,showing how a new skin of photovoltaic panels is to be draped over its facade and forecourt(architects: Kiss + Carthcart, New York, and Sommer & Partner, Berlin).

Building-Integrated Photovoltaics for Commercial and Institutional Structures

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Building-Integrated Photovoltaics for Commercial and Institutional Structures 1

ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Design Briefs

4 Times Square . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Thoreau Center for Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . .7

National Air and Space Museum . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Ford Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Western Area Power Administration . . . . . . . . . . . . . . . . . . . . . . .24

Photovoltaic Manufacturing Facility . . . . . . . . . . . . . . . . . . . . . . .28

Yosemite Transit Shelters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Sun Microsystems Clock Tower . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

State University of New York, Albany . . . . . . . . . . . . . . . . . . . . . .38

Navajo Nation Outdoor Solar Classroom . . . . . . . . . . . . . . . . . . . .40

General Services Administration, Williams Building . . . . . . . .42

Academy of Further Education . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

Discovery Science Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Solar Sunflowers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

Ijsselstein Row Houses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Denver Federal Courthouse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

BIPV Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

BIPV Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Appendix A: International Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . .71

Appendix B: Contacts for International Energy Agency Photovoltaic Power Systems Task VII—Photovoltaics in the Built Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77

Appendix C: Design Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

About the Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88

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IntroductionBuilding-integrated photovoltaic (BIPV) electric power systems not only produce electricity, theyare also part of the building. For example, a BIPV skylight is an integral component of the buildingenvelope as well as a solar electric energy system that generates electricity for the building. Thesesolar systems are thus multifunctional construction materials.

The standard element of a BIPV system is the PV module. Individual solar cells are interconnectedand encapsulated on various materials to form a module. Modules are strung together in anelectrical series with cables and wires to form a PV array. Direct or diffuse light (usually sunlight)shining on the solar cells induces the photovoltaic effect, generating unregulated DC electricpower. This DC power can be used, stored in a battery system, or fed into an inverter thattransforms and synchronizes the power into AC electricity. The electricity can be used in thebuilding or exported to a utility company through a grid interconnection.

A wide variety of BIPV systems are available in today's markets. Most of them can be grouped into two main categories: facade systems and roofing systems. Facade systems include curtainwall products, spandrel panels, and glazings. Roofing systems include tiles, shingles, standingseam products, and skylights. This sourcebook illustrates how PV modules can be designed asaesthetically integrated building components (such as awnings) and as entire structures (such asbus shelters). BIPV is sometimes the optimal method of installing renewable energy systems inurban, built-up areas where undeveloped land is both scarce and expensive.

The fundamental first step in any BIPV application is to maximize energy efficiency within thebuilding’s energy demand or load. This way, the entire energy system can be optimized.Holistically designed BIPV systems will reduce a building’s energy demand from the electric utility grid while generating electricity on site and performing as the weathering skin of thebuilding. Roof and wall systems can provide R-value to diminish undesired thermal transference.Windows, skylights, and facade shelves can be designed to increase daylighting opportunities in interior spaces. PV awnings can be designed to reduce unwanted glare and heat gain. Thisintegrated approach, which brings together energy conservation, energy efficiency, buildingenvelope design, and PV technology and placement, maximizes energy savings and makes themost of opportunities to use BIPV systems.

It is noteworthy that half the BIPV systems described in this book are on Federal buildings. This isnot surprising, however, when we consider these factors: (1) the U.S. government, with more thanhalf a million facilities, is the largest energy consumer in the world, and (2) the U.S. Department of Energy (DOE) has been directed to lead Federal agencies in an aggressive effort to meet thegovernment’s energy-efficiency goals. DOE does this by helping Federal energy managers identifyand purchase the best energy-saving products available, by working to increase the number andquality of energy projects, and by facilitating effective project partnerships among agencies,utilities, the private sector, and the states.

2 Building-Integrated Photovoltaics for Commercial and Institutional Structures

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Because it owns or operates so many facilities, the U.S. government has an enormous number ofopportunities to save energy and reduce energy costs. Therefore, the Federal Energy ManagementProgram (FEMP) in DOE has been directed to help agencies reduce energy costs, increase theirenergy efficiency, use more renewable energy, and conserve water. FEMP's three major work areasare (1) project financing; (2) technical guidance and assistance; and (3) planning, reporting, andevaluation.

To help agencies reach their energy-reduction goals, FEMP’s SAVEnergy Audit Program identifiescost-effective energy efficiency, renewable energy, and water conservation measures that can beobtained either through Federal agency appropriations or alternative financing. FEMP's national,technology-specific performance contracts help implement cutting-edge solar and other renewableenergy technologies. In addition, FEMP trains facility managers and showcases cost-effectiveapplications. FEMP staff also identify Federal market opportunities and work with procurementorganizations to help them aggregate purchases, reduce costs, and expand markets.

All these activities ultimately benefit the nation by reducing building energy costs, saving taxpayersmoney, and leveraging program funding. FEMP’s activities also serve to expand the marketplace for new energy-efficiency and renewable energy technologies, reduce pollution, promoteenvironmentally sound building design and operation, and set a good example for state and localgovernments and the private sector.

This sourcebook presents several design briefs that illustrate how BIPV products can be integratedsuccessfully into a number of structures. It also contains some basic information about BIPV andrelated product development in the United States, descriptions of some of the major software designtools, an overview of international activities related to BIPV, and a bibliography of pertinentliterature.

The primary intent of this sourcebook is to provide architects and designers with useful informationon BIPV systems in the enclosed design briefs. Each brief provides specific technical data about theBIPV system used, including the system’s size, weight, and efficiency as well as number of invertersrequired for it. This is followed by photographs and drawings of the systems along with generalsystem descriptions, special design considerations, and mounting attachment details.

As more and more architects and designers gain experience in integrating photovoltaic systems into the built environment, this relatively new technology will begin to blend almost invisibly into the nation’s urban and rural landscapes. This will happen as BIPV continues to demonstrate acommercially preferable, environmentally benign, aesthetically pleasing way of generatingelectricity for commercial, institutional, and many other kinds of buildings.

Building-Integrated Photovoltaics for Commercial and Institutional Structures 3

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Close-up view of curtain wall illustrates that BIPV panels (dark panels) can be mountedin exactly the same way as conventional glazing (lighter panels).

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4 design briefs: 4 Times Square

4 Times SquareLocation: Broadway and 42nd Street, New York City, New York

Owner: Durst Corporation

Date Completed: September 1999

Architect & Designer: Fox & Fowle Architects, building architects; Kiss + Cathcart Architects, PV system designers

PV Structural Engineers: FTL/Happold

Electrical Engineers: Engineers NY

Tradesmen Required: PV glazing done by shop labor at curtain wall fabricator

Applicable Building Codes: New York City Building Code

Applicable Electric Codes: New York City Electrical Code and National Electric Code

PV Product: Custom-sized BIPV glass laminate

Size: 14 kWp

Projected System Electrical Output: 13,800 kWh/yr

Gross PV Surface Area: 3,095 ft2

PV Weight: 13.5 lb/ft2

PV Cell Type: Amorphous silicon

PV Module Efficiency: 6%

PV Module Manufacturer: Energy Photovotaics, Inc.

Inverter Number and Size: Three inverters; two 6 kW (Omnion Corp.), one 4 kW (Trace Engineering)

Inverter Manufacturers: Omnion Corp. and Trace Engineering

Interconnection: Utility-Grid-Connected

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Description The tallest skyscraper built in New YorkCity in the 1990s, this 48-story office towerat Broadway and 42nd Street is a some-what unusual but impressive way todemonstrate "green" technologies. Itsdevelopers, the Durst Organization, wantto show that a wide range of healthybuilding and energy efficiency strategiescan and should be incorporated into realestate practices.

Kiss + Cathcart, Architects, are consul-tants for the building tower’s state-of-the-art, thin-film BIPV system. Working incollaboration with Fox and Fowle, archi-tects for the base building, Kiss + Cathcarthave designed the BIPV system to func-tion as an integral part of the tower's curtain wall. This dual use makes it one of the most economical solar arrays ever installed in an urban area. EnergyPhotovoltaics of Princeton, New Jersey,developed the custom PV modules tomeet rigorous aesthetic, structural, andelectrical criteria.

Traditionally, solar technologies havebeen considered economical only inremote areas far from power grids or inareas with an unusually high amount ofsunlight. Advances in PV efficiency areoverturning these assumptions, allowingsolar electricity to be generated cost-effectively even in the heart of the city. In fact, PV is the most practical means ofgenerating renewable electricity in anurban environment. Further, BIPV can bedirectly substituted for other claddingmaterials, at a lower material cost thanthe stone and metal it replaces. As thefirst major commercial application of BIPV in the United States, 4 Times Squarepoints the way to large-scale productionof solar electricity at the point of greatestuse. The next major market for PV maywell be cities like New York that have bothhigh electricity costs and high-qualitybuildings.

Special Design ConsiderationsThe south and east facades of the 37ththrough the 43rd floor were designated as the sites for the photovoltaic "skin."BIPV was incorporated into the designafter the tower’s general appearance had already been decided upon, so the

design briefs: 4 Times Square 5

BIPV panels have beenintegrated into thecurtain wall instead ofconventional glassspandrel panels on the37th through the 43rdfloor.

The custom-made BIPVpanels are visible in thissidewalk view fromBroadway.

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installation was made to harmonize withthe established design concept.

PV System ConfigurationThe PV modules replace conventionalspandrel glass in the south and eastfacades. There are four different sizes of modules, and they correspond to thespandrel sizes established earlier in thedesign process.

PV Module Mounting andAttachment DetailsThe PV modules are attached to the build-ing structure in exactly the same way thatstandard glass is attached. The glassunits are attached with structural siliconeadhesive around the back edge to an alu-minum frame. An additional silicone beadis inserted between the edges of adjacentpanels as a water seal.

There is a separate electrical system foreach facade. Each system consists of twosubsystems, feeding two 6-kW invertersand one 4-kW inverter. The larger invert-ers serve the two large-sized PV modules,which have electrical characteristics thatare different from those of the smallerones. Using multiple inverters enables thesystem to perform more efficiently. Theinverters are located in a single electricalcloset at the core of the building. The ACoutput of the inverters is transformedfrom 120 V to 480 V before being fed intothe main electrical riser.

6 design briefs: 4 Times Square

4 Times Square during construction

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sLocation: Presidio National Park, Building 1016, San Francisco, California

Owner: U.S. Department of Interior, National Park Service

Date Completed: May 1996

Architect & Designer: Tanner, Leddy, Maytum, Stacy

Structural and Electrical Engineers: Equity Builders

Tradesmen Required: Glaziers

Applicable Building Codes: California structural and seismic codes

Applicable Electric Codes: National Electric Code

PV Product: Roof-integrated, translucent glass-laminate skylight

Size: 1.25 kWp

Projected System Electrical Output: 716.4 kWh/yr/AC

Gross PV Surface Area: 215 ft2

PV Weight: 8 lb/ft2

PV Cell Type: Polycrystalline silicon

PV Efficiency: 11% cell, 7% module

PV Module Manufacturer: Solar Building Systems, Atlantis Energy

Inverter Size: 4 kW

Inverter Manufacturer and Model: Trace Engineering Model 4048

Interconnection: Utility-Grid-Connected

design briefs: Thoreau Center for Sustainability 7

Thoreau Center for Sustainability

Presidio National Park, Building 1016

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The first application forintegrating photovoltaicsinto a Federal building is theskylighted entryway of theThoreau Center in PresidioNational Park.

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DescriptionThe Greening of the Presidio demon-strates the impact of successful partner-ships between the private and publicsector. The Thoreau Center for Sustain-ability is a historic building, located in theNational Historic Landmark District of thePresidio in San Francisco, California. Thegoal of transforming this historic buildinginto an environmentally responsive struc-ture produced an opportunity to applyprinciples of sustainable design andarchitecture and educate the public aboutthem. Within this building rehabilitationproject, materials selected for the renova-tion included recycled textile materials,recycled aluminum, recycled newsprint,recycled glass, and wood grown and harvested sustainably.

The environmentally friendly strategyincluded reducing energy consumptionthrough a Demand Side Management(DSM) Program with the local utility com-pany, PG&E. The building has a highly effi-cient direct/indirect lighting system withtranslucent office panels to allow innerzones to borrow daylight from the perime-ter. The building is heated by an efficientmodular boiler and is cooled by naturalventilation. The BIPV system is a highlyvisible sustainable building feature. Thedemonstration of this power system byDOE FEMP, the National RenewableEnergy Laboratory (NREL), and numerousprivate-sector partners illustrates thatBIPV is a technically and economicallyvaluable architectural element for designers.

The skylit entryway of the Thoreau Centerfor Sustainability at Presidio NationalPark was the first demonstration in theUnited States of the integration of photo-voltaics into a federal building. Laminatedto the skylight glass are photovoltaic cellsthat produce electricity and also serve as a shading and daylighting design ele-ment. Atlantis Energy provided custom-manufactured PV panels and the systemdesign and integration for this project.The firm was joined by construction specialists who made it possible to transform this historic building into anenvironmentally responsive structure.

The solar electricity generated in the PV system in the skylight offsets power

provided by the utility, thereby conservingfossil fuels and reducing pollution.Converting the DC electricity to AC, thesystem can produce about 1300 wattsduring periods of full sun. The system is fully automatic and requires virtually no maintenance. Like other PV systems,it has no moving parts, so this solar generating system provides clean, quiet,dependable electricity.

The entry area into the Thoreau Center isa rectangular space with a roof slopingslightly to the east and west. The roof isconstructed entirely of overhead glazing,similar to a large skylight. PV cells arelaminated onto the 200 square feet ofavailable overhead glazing to produceapproximately 1.25 kW of electricity understandard operating conditions. The PV-produced DC electric power is convertedto high-quality AC by a power-conditioningunit (inverter). After it is converted, thepower enters the building to be consumedby the building’s electrical loads.

Special Design ConsiderationsDesign and construction issues for the relatively small Thoreau Center systemwere similar in many ways to issuesinvolved with designing and constructingmuch larger systems. The panels for this

project were custom-manufactured byAtlantis Energy to meet the estheticrequirements of the architect. The square,polycrystalline PV cells are spaced farenough apart from one another to permitdaylighting and provide pleasant shad-ows that fall within the space. The amountof daylight and heat transfer throughthese panels was considered in determin-ing the lighting and HVAC requirementsfor the space. The panels themselveswere constructed to be installed in a stan-dard overhead glazing system framework.

The system is installed above seismic-code-approved skylight glazing. The day-lighting and solar gains through the PVmodules mounted above the skylight sys-tem do affect the building lighting andHVAC loads, but the modules do not alsoserve as the weathering skin of this build-ing envelope. Originally, the design calledfor the PV modules to replace the skylightunits. But during design approval, localbuilding code authorities were uncertainwhether the modules could meet seismiccode requirements. So the alternativedesign, stacking the skylights and themodules, was used instead.

To ensure that the glazing used in manu-facturing the PV panels was acceptableaccording to Uniform Building Codes

8 design briefs: Thoreau Center for Sustainability

The PV arrays produce electricity and serve as a daylighting designelement.

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design briefs: Thoreau Center for Sustainability 9

This schematic drawing shows how the PV modules were attached above the conventional skylight glazing.

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(UBC), building code issues wereaddressed. Special arrangements weremade with the local electrical utility toensure that the grid-tied system wouldmeet safety requirements. Finally,installing the system required coordina-tion between the panel supplier, electri-cian, glass installer, and Presidio facilitiespersonnel.

PV System Configuration The BIPV glazing system consists of 24 PVglass laminates. The spacing of the cellswithin the modules allows approximately17% of the sunlight into the entryway,reducing the need for electric lights. Themodules consist of 6-mm Solarphireglass, 36 polycrystalline silicon PV cells,

an ethylene-vinyl acetate coating, atranslucent Tedlar-coated polyester back-sheet, and two sealed and potted junctionboxes with a double pole plug connector.The PV cells are laminated in a 6-cell x 6-cell matrix. The minimum spacingbetween cells is 1.25 cm (1/2 in.). Thedimension of each module is 81 cm x94 cm (32 in. x 37 in). The gross area ofthe entire structure is 18.8 m2 (200 ft2).

The power produced by the system is con-verted to high-quality AC electricity andsupplements power supplied to the build-ing by the utility. The system is rated at1.25 kW. Each of the 24 PV modules gen-erates 8.5 V of DC power at approximately5.5 amps. Six modules per sub-array are

connected in series to feed the sine-waveinverter, which is configured to 48 V andrated at 4,000 W capacity.

PV Module Mounting andAttachment DetailsStructural upgrades were made to accom-modate the additional weight of the PVsystem. These added about $900 to thetotal cost, for structural components.

10 design briefs: Thoreau Center for Sustainability

This drawing shows how the photovoltaic skylight array was arranged. The total array area is 20.6 square meters.

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design briefs: National Air and Space Museum 11

National Air and Space MuseumLocation: Dulles Center, Washington, DC

Owner: Smithsonian Institution

Date Completed: Construction begun in 2000, scheduled for completion in 2003

Architect & Designer: HOK, Building Architects; Kiss + Cathcart Architects, PV System Designers; Satish Shah, Speigel, Zamel, & Shah, Inc.

Structural Engineers: N/A

Electrical Engineers: N/A

Tradesmen Required: Building tradesmen

Applicable Building Codes: BOCA, Metropolitan Washington Airport Authority

Applicable Electric Codes: National Electric Code

PV Product: Various BIPV systems

Size: To be determined for BIPV curtain wall, facades, and canopy

Projected System Electrical Output: 15.12 kWh for the canopy system

Gross PV Surface Area: 223 m2 for the canopy system

PV Weight: 5 lb/ft2 for the canopy system

PV Cell Type: Polycrystalline cells, amorphous silicon film for various systems

PV Efficiency: Systems will range from 5% to 12%

PV Module Manufacturer: Energy Photovoltaics, Inc., for the canopy system

Inverter Number and Size: To be determined

Inverter Manufacturer & Model: To be determined

Interconnection: Utility-Grid-Connected

Project Overview:Axonometric

PV CanopyPV Curtain Wall

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The BIPV installations at theentryway will demonstratedifferent BIPV systems andtechnologies, such as thinfilms and polycrystallinesolar cells.

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DescriptionThe National Air & Space Museum(NASM) of the Smithsonian Institution isone of the most-visited museums in theworld. However, its current building onthe Mall in Washington, D.C., can accom-modate only a fraction of NASM’s collec-tion of historical air- and spacecraft.Therefore, a much larger expansion facil-ity is planned for a site adjacent to DullesAirport. Since the new facility will exhibittechnologies derived from space explo-ration, the use of solar energy, which haspowered satellites and space stationssince the 1950s, is especially fitting forthis new building.

Kiss + Cathcart, Architects, are under contract to the National RenewableEnergy Laboratory as architectural-photovoltaic consultants to theSmithsonian Institution. Working with the Smithsonian and HOK Architects, Kiss + Cathcart is identifying suitableareas for BIPV, selecting appropriate technologies, and designing the BIPV systems. For DOE FEMP, a partner in theproject, a primary goal is to demonstratethe widest possible range of BIPV applica-tions and technologies in one building.Construction should begin in 2000.

The NASM Dulles Center will serve as an exhibit and education facility. Its

core mission is to protect the nation’s collection of aviation and space-flight-related artifacts. It will also house thepreservation and restoration workshopsof the Air and Space Museum.

The center’s design includes a large,hangar-style main exhibition space thatwill allow visitors to view the collectionsfrom two mezzanines as well as fromground level. It is estimated that morethan 3 million people will visit the centerannually to view aircraft, spacecraft, andrelated objects of historic significance,many of which are too large to display atthe National Air and Space Museum inWashington, D.C. The facility will set new

12 design briefs: National Air and Space Museum

Plan view of BIPV installation at entry areas

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design briefs: National Air and Space Museum 13

The south- and west-facing facades of the entry hall will be glazed with polycrystalline glass laminates.

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standards for collections managementand the display of large, 20th-centuryfunctional objects.

Smithsonian staff are evaluating the inte-gration of a number of grid-connectedBIPV systems into the building. The NASMDulles Center will be a very large structure(740,000 ft2), with commensurate energyand water requirements. As part of itseducational mission, the museum plansto exhibit hardware that points to the historic use of photovoltaic (PV) powersystems in space; the museum would also like to demonstrate how that tech-nology can be used today in terrestrialapplications such as BIPV. To this end, the Smithsonian is evaluating the highlyvisible application of BIPV at this facilityto meet a portion of its energy require-ments. In this way, two objectives will be

met: (1) reduce the amount of energyrequired from the power grid, especiallyduring peak times, and thus conserveenergy and save operational funds, and(2) demonstrate the use of PV in a highlyvisible context in a much-visited Federalfacility.

Five BIPV subsystems could be demon-strated at the new NASM facility, includingthe south wall and skylight of the entry"fuselage," the roof of the restorationhangar and space shuttle hangar, thefacade of the observation tower, andawning canopies. The entry fuselage figure clerestory windows will be a highlyvisible way of demonstrating PV to visi-tors approaching the center. Once in theentryway, visitors would also see the patterns of shadow and light the frittedglass creates on the floor, thus focusing

visitors attention on the PV. Labels,exhibit material, and museum tour staffcould further highlight the PV arrays andcall attention to the energy savings beingrealized. PV would also be used to powersome exhibit material exclusively. Therelated exhibit materials could highlightthe many connections between PV andthe field of space exploration and utiliza-tion, as well as today’s construction andbuilding industry.

14 design briefs: National Air and Space Museum

BIPV Canopy detail 1:10

Canopy:Structural Details

BIPV Canopy - section 1:60

02527219m

Thin-film BIPV glasslaminates will functionas the canopy.

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design briefs: National Air and Space Museum 15

Fuselage detail illustrates patterns of polycrystalline glazing.

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16 design briefs: National Air and Space Museum

Curtain wall details indicate how mullion channels will act as electrical conduits.

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design briefs: National Air and Space Museum 17

The canopy plan and perspective demonstrate how shading and power output are combined in one architecturalexpression.

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18 design briefs: National Air and Space Museum

Curtain walls typically will be 16 polycrystalline solar cells per panel, laminated between two clear glass panes.

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design briefs: Ford Island 19

Ford Island

Building 44, Pearl Harbor Naval Station

This illustration is a view of the building from the southwest corner; the dark areasrepresent the photovoltaic standing-seam metal roofing material.

Location: Honolulu, Hawaii

Owner: U.S. Navy, Department of Defense, and Hawaiian Electric Company

Date Completed: September 1999

Architect & Designer: Victor Olgyay, Fred Creager, and Stephen Meder, University of Hawaii, School of Architecture

Structural Engineers: Hawaiian Electric Co.

Electrical Engineers: Hawaiian Electric Co.; Peter Shackelford, Renewable Energy Services, Inc., system integrator

Tradesmen Required: Roofers, electrical contractors

Applicable Building Codes: Uniform Building Code

Applicable Electric Codes: National Electric Code

PV Product: Integrated standing seam metal roof

Size: 2.8 kW DC

Projected System Electrical Output: 9,720 kWh per month

Gross PV Surface Area: 571 ft2

PV Weight: 4 lb/ft2, with the roof

PV Cell Type: Multijunction amorphous silicon

PV Module Efficiency: 5%-6%

PV Module Manufacturer: Uni-Solar

Inverter Number and Size: One, 4-kW

Inverter Manufacturer and Model: Trace SW 4048PV

Interconnection: Utility-Grid-Connected

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DescriptionA partnership consisting of the U.S. Navy,Hawaiian Electric Co. (HECO), theUniversity of Hawaii, the U.S. DOE FederalEnergy Management Program (FEMP),and the Utility PhotoVoltaic Group (UPVG)was created in order to design and installa 2-kW, grid-intertied, BIPV retrofit sys-tem using the Uni-Solar standing seammetal roofing product and to monitor itsperformance for one year. The Universityof Hawaii School of Architecture designedand administered the project and a localutility, HECO, funded it. Additional con-struction cost support was supplied byFEMP, NREL, and the Navy. The utility andthe Navy determined the site, and theinstallation date was scheduled for thethird quarter of 1998 (Figure 1). HECO wasdesignated to be the client for the firstyear, after which the Navy will assumeownership of the system.

The tropical location (21° North) and thesite’s microclimate make it an ideal loca-tion for PV installations. Project plannersexpected an annual daily average of5.4 peak sun hours and 20 to 25 in.(57 cm) of annual rainfall. This project, atthis particular site, will also be testing thelimits of the products used in the installa-tion. Monitoring the performance of the

PV system, the McElroy metal substrate,and the Trace inverter in a tropical marineenvironment will provide valuable perfor-mance information to guide the futuredevelopment and use of these products.

The total cost of this project was $92,000.This included design, procurement, roofremoval and BIPV installation, and a yearof monitoring.

Special Design ConsiderationsThe context of this project is the navalindustrial site at Pearl Harbor NavalBase.The site contained a 90 ft x 52 ft(27.4 m x 15.8 m) open-wall boathousestructure. The existing roof of the struc-ture was made of box rib metal on trusses(Figure 2) in gable form, divided longitudi-nally on its east-west axis. The south

20 design briefs: Ford Island

In this illustration, the dark areas represent amorphoussilicon laminates on standing seam metal roofing panels.

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The array in mid-installation is shaded only by cloud cover.

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slope provides a 90 ft x 26 ft (27.4 m x7.9 m) surface at a 5° incline. This half of the roof measured approximately2,340 ft2 (217 m2). The box rib roofingwas removed from the entire south-facingslope, and new standing seam pans,including 24 of the Uni-Solar SSR 120photovoltaic standing seam panels,replaced the original roofing.

Integrating the new metal roofing with the existing roof posed several designand construction challenges. In addition,the longest panel that Uni-Solar could

provide is 20 ft (6.09 m) and the requiredrun is 26+ ft (8 m). This shortfall requiredoverlapped joints to be used on the endsof the panels and additional purlines to be welded for support. Full-length,standing-seam panels and non-PV panelswere set in an alternating pattern with the PV modules. This arrangementallowed the full-length pans to addstrength over the required lap joint of the shorter PV units.

The length limitation of the Uni-Solar panels was a design deficiency of the

Uni-Solar product; unless new PV-to-metal laminating processes are devel-oped, this product will be substantiallylimited in metal roofing applications.Joining the panels to extend their lengthnot only increases material and laborcosts, it also provides opportunities forwater penetration and corrosion. The"galvalum" coating is cut away every-where the panel is modified. This exposesthe steel of the standing seam panel tothe marine environment. Therefore,McElroy, Uni-Solar’s metal roof supplier,will not warranty the product for marineapplications.

In addition, to match the paint of theexisting structure, McElroy required aminimum order to custom-paint the newroof panels. Therefore, about one-thirdmore roofing panels had to be purchasedthan were needed, and this increased theoverall project cost. The extra panelsturned out to be useful, however, sincemany were damaged during transport toHawaii.

The part of the roof to be retrofitted spansa dock area below. This presented stagingchallenges for the roofing and electricalcontractors. Along with restricted accessto the military base and the need to take abridge to the site, the location of the roofadded to the complexity and costs of theproject. And the harsh marine environ-ment could have a corrosive effect on thearray and its components.

PV System ConfigurationThe system is rated at 2.175 kW AC(2.8 kW DC). The estimated system out-put is 9,720 kWh per month. The buildingis not independently metered. It is fed bythe Pearl Harbor grid, to which HECO sup-plies power. The estimated demand of thebuilding is about 12000 kWh per month.The energy generated by the PV systemwill feed but not meet the average loadsof this building.

PV Module Mounting andAttachment DetailsIntegrated connection follows standardmetal seam roof attachment process.Notched PV panels are secured to non-PVpanels with metal fasteners.

design briefs: Ford Island 21

This illustration shows how the notched BIPV standing-seam componentsoverlap the regular roofing panels.

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22 design briefs: Ford Island

Junction box at ridge, viewed from below

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Junction box at ridge, viewed from above

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Additional electrical junction boxes were required overpotted terminals and raceways at the ridge, before theridge cap was installed.

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Workers install short lapped roofing pans at BIPVmodule sections.

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design briefs: Ford Island 23

The part of the roof containing BIPV spans a dock area, as shown in this illustration.

0252

7289

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24 design briefs: Western Area Power Administration

Western Area Power Administration

Elverta Maintenance Facility, Phases I and IIPhase I

Location: Elverta, California

Owner: U.S. Department of Energy (DOE) Western Area Power Administration

Date Completed: May 1996

Architect & Designer: DOE Western Area Power Administration, PowerLight Corporation

System Integrator: PowerLight Corporation

Structural Engineers: DOE Western Area Power Administration

Electrical Engineers: DOE Western Area Power Administration

Tradesmen Required: Roofers, electrical contractors

Applicable Building Codes: Standard California building codes

Applicable Electric Codes: National Electric Code

PV Product: PowerGuard™ BIPV roof tiles

Size: 40 kW DC

Projected System Electrical Output: 70,000 kWh/year

Gross PV Surface Area: 5,400 ft2

PV Weight: 4 lb/ft2

PV Cell Type: Polycrystalline silicon

PV Efficiency: 12%

PV Module Manufacturer: Solarex

Inverter Number and Size: 8 inverters, 6 kW each

Inverter Manufacturer: Omnion Corp.

Interconnection: Utility-Grid-Connected

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A 38-kW BIPV system supplements a 40-kW system installed in 1996.

Phase I

Phase II

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DescriptionStaff in the Department of Energy’sWestern Area Power Administration Sierra Nevada Region (SNR) have had twomain goals for SNR's photovoltaic (PV)program: (1) promote PV systems as arenewable energy resource, and (2) do so in a cost-effective manner. In supportof these goals, SNR has incorporated PV panels into the roofs of buildings inElverta and Folsom, California. The build-ing-integrated systems will repay invest-ments in them by extending roof lives,reducing maintenance costs, generatingelectric power, and reducing the build-ings' cooling requirements.

In Phase I, a 40-kW building-integratedphotovoltaic system was installed atSNR's Elverta Maintenance Facility. TheSacramento Municipal Utility District(SMUD) funded the PowerLight Corp.PowerGuard® system, while Western contributed funds equivalent to the costof replacing the facility roof. Funding wasalso provided by the Utility PhotovoltaicGroup (UPVG) through TEAM-UP, withsupport from the U.S. Department ofEnergy.

With a power capacity of 40 kW peak DCand an annual energy output of more than 70,000 kWh/year, the PV systemshave significant environmental benefits.Phase I prevents the emission of2,300 tons of carbon dioxide, 8.7 tons of nitrogen oxides and 16.4 tons of sulfurdioxides; these emissions would be theresult if fossil fuels were burned to generate the same amount of electricity.Because this system is designed to have a life expectancy of 20 years, the cumula-tive benefits for the environment aremany.

Special Design ConsiderationsPowerGuard PV tiles were used to reroofthe building, saving on the cost of con-ventional roofing material. The patentedPowerGuard tiles incorporate high-effi-ciency polycrystalline silicon cells fromSolarex. Site conditions were favorablefor this sytem: 38° latitude; a dry, sunnyclimate throughout most of the year; andno shading. The system features horizon-tal tiles and tiles with an 8° southerly tilt

for greater annual energy production. Inaddition to generating clean renewableenergy, the lightweight system providesR10 roof insulation for improved buildingcomfort and membrane protection forextended roof life. Installation took only7 days to complete once the building'sold roof was replaced with a new single-ply membrane roof.

PV System ConfigurationA 40-kW PowerGuard building-integratedPV system was installed at the ElvertaMaintenance Facility in Western's SierraNevada Region to function as both a roofand solar electric photovoltaic (PV) powerplant. Phase I modules were installed inparallel strings containing 56 modules perstring (7 series, 8 parallel).

design briefs: Western Area Power Administration 25

A view of the rooftop of the Elverta facility after the PV system installation.

A PowerLight rooftop PV system is installed on Western’s facility inElverta, California.

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PV Module Mounting andAttachment DetailsThe panels are designed to interlockusing a tongue-and-groove assembly.Panels with 3/8-in. concrete topping,instead of PV modules, are set among the PV panels to allow working accessthroughout the roof. Along the edges of the PV array, a steel ribbon links themodules together, in order to connecteverything structurally.

26 design briefs: Western Area Power Administration

The temperature curves show how the PV-integrated roof compares with various roofs without solar electricsystems. Roof-integrated PV with integral insulation reduces a building’s heat load as much as 23°C. Themeasurements were derived from sensors placed in representative roof specimens.

02527230m

Workers carry PV modules with attached foam backing in preparation forrooftop mounting. Smaller panels with concrete topping were alsoinstalled as a walking surface.

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Description This 38-kW BIPV system supplements thePhase I system. Both systems completelycover the Elverta roof and are the largestPV application of its kind in the UnitedStates. Phase II is totally funded andowned by Western. The PV systems utilizethin-film amorphous silicon technology.The DC output from the PV modules isconverted to 240 V AC by means of a custom-built 32-kW Trace inverter, andthen stepped up to 480 V, three-phase AC by a 45-kVA transformer for direct connection to the building's servicepanel. Besides replacing grid power, thePowerlight system protects the roof membrane, which extends its life. The roofsystem also provides R10 insulation toreduce cooling and heating loads, therebydecreasing energy consumption.

Special Design ConsiderationsThe flush roof design provides excellentinsulation as well as electricity, as shownin the graph comparing roof temperaturedata.

PV System ConfigurationThe Solarex modules were installed in254 parallel strings, with three Solarexmodules in series per string. The modules

produce 43 watts each. The APS moduleswere installed in 22 parallel strings with12 modules in series per string. The APSmodules produce 22 watts each.

PV Module Mounting andAttachment DetailsSame as those for Phase I.

design briefs: Western Area Power Administration 27

The illustration shows how the layers in the roofs provide above-averageinsulation as well as a good base for the PowerGuard PV system.

RoofingMembrane

Solar ElectricPanel

Styrofoam®Insulation

Substrate Roof Deck 02527234m

Phase II Location: Elverta, California

Owner: U.S. Department of Energy (DOE) Western Area Power Administration

Date Completed: June 1998

Architect & Designer: DOE Western Area Power Administration, PowerLight Corporation

System Integrator: PowerLight Corporation

Structural Engineers: DOE Western Area Power Administration

Electrical Engineers: DOE Western Area Power Administration

Tradesmen Required: Electrical and building contractors

Applicable Building Codes: Standard California building codes

Applicable Electric Codes: National Electric Code

PV Product: PowerGuard™ BIPV roof tiles

Size (kWp): 38 kW DC

Projected System Electrical Output: 67,500 kWh/year

Gross PV Surface Area: 9,900 ft2

PV Weight: 5 lb/ft2

PV Cell Type: Thin-film amorphous silicon

PV Efficiency: 4%-5%

PV Module Manufacturer: Solarex (762 modules) and APS (264 modules)

Inverter Number and Size: One 32-kW AC

Inverter Manufacturer and Model: Trace Technologies

Interconnection: Utility-Grid-Connected

Phase I

Phase II

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28 design briefs: Photovoltaic Manufacturing Facility

Photovoltaic Manufacturing FacilityLocation: Fairfield, California

Owner: BP Solar

Date Completed: 1993

Architect & Designer: Kiss Cathcart Anders, Architects

Structural Engineers: Ove Arup & Partners

Electrical Engineers: Ove Arup & Partners

Tradesmen Required: Glaziers, electricians

Applicable Building Codes: BOCA and California Title 24

Applicable Electric Codes: National Electric Code

PV Product: Glass laminates as curtain wall spandrel, skylight, and awning

Size: 9.5 kWp

Projected System Electrical Output: 7.9 kW

Gross PV Surface Area: 1,975 ft2

PV Weight: 3 lb/ft2

PV Cell Type: Amorphous silicon

PV Efficiency: 5%

PV Module Manufacturer: APS

Inverter Number and Size: 6 kW

Inverter Manufacturer: Omnion Corporation

Interconnection: Utility-Grid-Connected

Views looking north (top) and south show how BIPV is integrated into both the facade and thecanopy that runs the length of the building.

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DescriptionCompleted in 1993, this 69,000-ft2 manu-facturing facility houses a new generationof production lines tailored to thin-film PV technology. The building also incorpo-rates into its design several applicationsof thin-film solar modules that are proto-types of BIPV products.

The heart of the project is a 22.5-ft-highBIPV glass cube containing the factory’scontrol center and visitor facilities. Thiscube is perched on the second floor, andhalf of it is outside of the manufacturingbuilding, emphasizing its status as anindependent element and a prototype

that demonstrates BIPV in a typical com-mercial building. The cube’s PV cladding,the solar entrance canopy, and the trans-lucent BIPV skylight provide more thanenough energy to power the control center’s lighting and air-conditioning systems.

The production floor and warehousespace are housed in a tilted-up concreteshell with a steel intermediate structureand a timber roof. Glass blocks embeddedas large-scale "aggregate" in the outsidewalls provide a pattern of light in the inte-rior during the day and on the exterior atnight. Mechanical service elements arecontained in a low, steel-framed structureon the north side of the building. Theentry court is paved in a pattern of tintedconcrete and uplighting that representsan abstracted diagram of solar energygeneration.

Special Design ConsiderationsIn addition to providing a working productdevelopment test bed for BIPV systems,the project serves an educational functionfor public and private groups. Thelobby/reception area provides displayspace for products and research. A pat-tern cast into the paving in front of themain entry combines a sun path diagramwith a representation of the photovoltaiceffect at the atomic level. The controlroom/cube also serves an educational

design briefs: Photovoltaic Manufacturing Facility 29

Interior view shows how BIPV isused with vertical and slopedglazing.

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This office interior view demonstrates the quality of light transmittedby the approximately 5% translucent BIPV panel skylight.

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30 design briefs: Photovoltaic Manufacturing Facility

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design briefs: Photovoltaic Manufacturing Facility 31

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32 design briefs: Photovoltaic Manufacturing Facility

Built-up roofing, min. slope 1/4" per 1'-0" to drain

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Sectional view indicates skylight configuration and curtain-wall facade.

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function; a raised platform allows groupsof visitors to view the control equipment,and beyond it, the production line.Computerized monitoring equipment dis-plays the status of the PV systems as wellas information regarding building HVACand lighting energy use, exterior ambientconditions, insolation, and other data.

Wherever possible, the PV systems aredesigned to do double duty in terms ofenergy management by reducing heatgain while providing power. The curtainwall and skylight are vented, eliminatingradiant heat gain from the modules andenhancing natural ventilation in the cube.The awning is designed to shade the rowof south-facing windows that open intothe production area and employeelounge. The cube curtain wall integratesPV modules with vision glass in a standard pressure plate curtain wall framing system, modified to be self-ventilating. The system is intended to be economical and adaptable to new construction or retrofit.

PV System ConfigurationThe PV module is a nominal 2.5 ft x 5.0 ft,a-Si thin-film device rated at 50 Wp stabi-lized. The PV system contains 84 full-sizemodules mounted on the awning, 91 mod-ules installed in the curtain wall, and 8 ina skylight. The curtain wall modules areinstalled in custom sizes as required byarchitectural conditions. The system has a total capacity of 7.9 kW; because of thevarying orientations of the modules, thepeak output is 5 kW. Despite the hot localclimate, the power consumed by the cubefor cooling and lighting never exceeds3.5 kW, producing a surplus of PV powerwhich is directed into the main buildinggrid.

PV Module Mounting andAttachment DetailsStandard PV modules are 31 in. x 61 in.but can be produced in custom sizes asrequired to fit the framing requirements ofthe curtain wall. One unique feature isthat the modules are glass-to glass lami-

nated products. The modules are installedwith an insulated inner liner, which formsa plenum for ventilation. Heat radiatedinto the curtain wall plenum is vented tothe outside by natural convection throughholes drilled in the horizontal mullions. Insome cases, the hollow vertical mullionsare used as ducts to direct the warm airupward.

The skylight panels are standard modulesthat transmit approximately 5% of thesunlight through the laser scribe lines.The PV modules are supplemented byclear glazing units to increase light trans-mission. Another unique feature of thisBIPV system is that the skylight is ventedto remove heat gain from the modules.

The awning panels are bolted through thesteel tube awning structure to aluminumchannels epoxied to the encapsulatingglass. This is the attachment used in typi-cal field-mounted arrays.

design briefs: Photovoltaic Manufacturing Facility 33

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34 design briefs: Yosemite Transit Shelter

Yosemite Transit Shelters

The transit shelter prototype makes use of both high-tech and low-tech materials, combininglocally forested lumber with BIPV panels.

02527238m

Location: Yosemite National Park, California

Owner: U.S. Department of Interior, National Park Service

Date Completed: Scheduled for system completion in 2001

Architect & Designer: Kiss + Cathcart, Architects

Structural Engineers: Ove Arup & Partners, Structural Engineers

Electrical Engineers: None; design overview provided by inverter manufacturer

Tradesmen Required: Standard Contractor/Carpenter and Electrician

Applicable Building Codes: National Park Service, self-regulating

Applicable Electrical Codes: National Park Service, self-regulating

PV Product: Amorphous silicon glass panels

Size: 560 Wp per transit shelter

Projected System Electrical Output: 1.15 MWh/yr

Gross PV Surface Area: 112 ft2

PV Weight: 3.375 lb/ft2

PV Cell Type: Amorphous silicon

PV Efficiency: 6%

PV Module Manufacturer: Energy Photovoltaics, Inc.

Inverter Numbers and Size: 1 kW

Inverter Manufacturer: Advanced Energy Systems

Interconnection: Optional—Grid-Connected or Stand-Alone

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DescriptionYosemite National Park is one of the mosttreasured environments in the UnitedStates – and also the site of serious vehic-ular traffic congestion. The National ParkService is working to reduce traffic andpollution in Yosemite by expanding theshuttle bus service and introducing elec-tric shuttle buses. This necessitates aninfrastructure of combined weather shel-ters and information boards at the newshuttle stops.

Funded by DOE FEMP, Kiss + Cathcart,Architects, is under contract to NREL todesign a prototypical bus shelter incorpo-rating BIPV panels. The park will begininstalling the first of 19 new shuttle stopsin the summer of 2000. The shelters thatare near existing electrical lines will sendthe power they generate into the utilitygrid system serving Yosemite; the moreremote shelters will have battery storagefor self-sufficient night lighting.

Special Design ConsiderationsThe design mandate for this project is tobalance a sense of the rustic historicalbuilding style of the Yosemite Valley withthe frankly technological appearance ofBIPV systems. The overall structure is a composite of heavy timber and steelplates that serves two purposes: accom-modating heavy snow loads with mini-mum structural bulk and projecting anappearance that is rustic from a distancebut clearly modern in a close-up view. The structural timbers (unmilled logs from locally harvested cedar) are split in half, and the space between them isused for steel connections, wiring, andmounting signage. The BIPV roof struc-ture is made of a single log cut into eightseparate boards.

A shallow (10°) tilt was chosen for the PVroof. A latitude tilt of approximately 37°would provide the maximum annual out-put in an unobstructed site; however, ashallower angle is better suited toYosemite because of the considerableshading that occurs at low sun angles inthe valleys, especially in winter. A steeperslope would also have made the shuttlestop much taller, significantly increasingstructural loading and demanding a heav-ier structure. This was determined to be

undesirable in terms of both appearanceand material use.

PV System ConfigurationFourteen semitransparent, 40-W thin-filmmodules make up the PV system for eachshelter. Power is fed to a single inverter.Some systems will be grid-connected andsome will be stand-alone with batteriesfor backup.

PV Module Mounting andAttachment DetailsThe PV roof of the shelter is not designedto be watertight like the roof of anenclosed building. Instead, it is designedto be waterproof so that water does notdrip through the roof in normal weatherconditions. Therefore, the PV modules areoverlapped (shingled) slightly along thecenter seam, and sheet metal gutters areinserted at the seam between the roughwood rafters and the modules.

design briefs: Yosemite Transit Shelter 35

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36 design briefs: Sun Microsystems Clock Tower

Sun Microsystems Clock Tower

North-facing view ofthe clock tower at SunMicrosystems facility.

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Location: Burlington, Massachusetts

Owner: Sun Microsystems

Date Completed: October 1998

Architect & Designer: HOK Architects and ASE Americas, Inc.

Structural Engineers: Whiting-Turner Contracting Co.

Electrical Engineers: Enertech Engineering

Tradesman Required: Glaziers, electricians

Applicable Building Codes: Uniform Building Code

Applicable Electrical Codes: National Electric Code Section 620

PV Product: BIPV curtain wall

Size: 2.5 kWp

Projected System Electrical Output: 2.5 kWp

Gross PV Surface Area: 827 ft2

PV Weight: 8.3 lb/ft2

PV Cell Type: Polycrystalline silicon manufactured by ASE Americas, Inc.

PV Efficiency: 12.8%

PV Module Manufacturer: Pilkington Solar International

Inverter Number and Size: One 2.5 kWp inverter

Inverter Manufacturer and Model: Omnion Power Corp.

Interconnection: Utility-Grid-Connected

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DescriptionASE Americas recently provided thedesign, PV panels, and electronic equip-ment needed to power an 85-ft high clocktower on Sun Microsystems' new 1 millionft2 campus in Burlington, Massachusetts.The architects who designed the buildingincluded both electrically active and elec-trically inactive glass panels on four sidesof the tower. The electrically active panelsincorporating PV modules were used onthe east and west sides. A diffuse lightpattern washes around the edges of thesolar cells in the inside of the tower to create a soft look in the interior. The clocktower load is primarily a nighttime load.Energy from the PV array goes into thebuilding by day, and the clock towerdraws power at night from the building'selectrical grid. This could be the first useof dual-glazed, thermally insulated PVpanels in a U.S. building structure.

Special Design ConsiderationsThe PV panels were custom designed tomatch the dimensions of the KawneerSeries 1600 mullion system used on thefour sides of the clock tower. They werefabricated as dual-glazed, thermally insulating panels with a glass-cell-glasslaminate as the outer surface and afrosted glass sheet as the inner surface.Some of the panels were required to wraparound the clock, so three different basicshapes were designed with round cuspscut out of the corners to match the curva-ture of the round, 7.5-ft-diameter clock.Two rectangular shapes were required sothe panels were vertically arranged tomatch the floor levels.

PV System ConfigurationThe PV modules are connected in seriesand feed electricity into an inverter thatconverts the 2.5 kW DC power to AC.

PV Module Mounting andAttachment DetailsEight electrically active panels were fulywired and interconnected through aninverter and transformer into the buildingwiring as a utility-interactive system.These systems are the simplest and mosteconomical way to install a PV powersource. There are no batteries in this typeof system, since the system draws powerfrom the building's electrical grid.

design briefs: Sun Microsystems Clock Tower 37

Pilkington Solar International’sproject leader, John Goldsmith, isshown with the integrated curtainwall on the south and west faces of the clock tower.

East view of the clock tower shows BIPV installation.

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38 design briefs: State University of New York, Albany

State University of New York, Albany

Looking southeastat the Center forEnvironmentalSciences andTechnologyManagement

Location: Albany, New York

Owner: State University of New York, Albany

Date Completed: Summer 1996

Architect: Cannon Architects

Electrical Engineer: Cannon Architects

Solar Consultant: Solar Design Associates, Inc.

Tradesmen Required: Beacon Sales Corporation, roofing contractors

Applicable building codes: New York State Building Code and ANSI Z97.1

Applicable electrical codes: National Electric Code

PV product: Kawneer 1600 PowerWall™

Size: 15 kWp

Project System Electrical Output: 19,710 kWh / yr.

Gross PV Surface Area: 1,500 ft2

PV Weight: 1.93 lb / ft2

PV Cell Type: Polycrystalline silicon

PV Cell Efficiency: 12%

PV Module Manufacturer: Solarex

Inverter Number and Size: AES 250 watt

Inverter Manufacturer and Model: Advanced Energy Systems Micro Inverter

Interconnection: Utility-Grid Connected

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DescriptionFor the new Center for EnvironmentalSciences and Technology Management(CESTM) at the State University of NewYork in Albany, Cannon Architects devel-oped an energy-conscious design strat-egy. This strategy included the integrationof solar electric systems into both thebuilding and the project site as landscape elements. The building incorporates15 kWp of custom PV modules in building-integrated sunshades that support the PV modules while reducing cooling loadsand glare on the south facade. The PVmodules feature module-integratedinverters.

Special Design ConsiderationsThis system was the first of its kind in theUnited States to tie together more than2 kW of AC modules, and the first to usethe AC module platform for a sunshade.AC modules proved to be far more effec-tive than a typical single inverter, giventhe different light levels on the modulesover the course of a day.

PV System ConfigurationThere are two different system configura-tions in the CESTM solar system. The sunshade portion consists of 59 pairs offramed Solarex MSX 120 modules. Eachpair is connected to its own accessible ACmicro-inverter. The inverters are installedinside the building for ease of service. Thelandscape portion consists of 18 pairs ofSolarex MSX 240 modules. An AC micro-inverter is attached to the underside ofeach pair.

PV Mounting and AttachmentDetailsSolarex provided framed PV modules thatwere modified to incorporate the AESmicro-inverters. Most of the moduleswere mounted in an aluminum strut, creating a solar sunshade. The rest of themodules were mounted above ground,along a curved pathway at the mainapproach to the building. The building’ssunshades use standard extrusions fromthe Kawneer curtain wall system, theKawneer 1600 PowerWallTM. This customconfiguration provided structural supportto the modules.

design briefs: State University of New York, Albany 39

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40 design briefs: Navajo Nation Outdoor Solar Classroom

Navajo Nation Outdoor Solar Classroom

Each new BIPV structure at the Seba Dalkai School will serve as an open-air classroomsupported by timber columns in a concrete foundation.

Location: Seba Dalkai, Navajo Reservation, Arizona

Owner: Seba Dalkai Boarding School

Scheduled Completion Date: Fall 1999

Architect: Kiss + Cathcart, Architects

Electrical Engineer: Energy Photovoltaics, Inc.

Solar Consultant: Kiss + Cathcart, Architects

Tradesmen Required: Electricians, laborers

Applicable Building Codes: Standard building codes

Applicable Electrical Codes: National Electric Code

PV Product: Energy Photovoltaics EPV-40 modules

Size: 4.0 kWp

Projected System Electrical Output: 5,818 kWh/yr

Gross PV Surface Area: 625 ft2

PV Weight: 3.75 lb/ft2

PV Type: Amorphous silicon

PV Efficiency: 6%

PV Module Manufacturer: Energy Photovoltaics, Inc.

Inverter Number and Size: Four 2.5 kW inverters

Inverter Manufacturer: Trace Engineering

Interonnection: Stand-Alone System

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DescriptionThe Seba Dalkai Boarding School, aBureau of Indian Affairs school on theNavajo Reservation in Arizona, is con-structing a new K-8 facility to be com-pleted in 2001. Funded by DOE FEMP, thisfacility will incorporate a BIPV systemcapable of producing approximately4.0 kW of electricity.

The school is currently housed in a traditional hogan and in a stone facilitybuilt in the 1930s. These will remain andbe juxtaposed with a new school facility.The photovoltaic component of this project will mediate between the old andthe new, and it will add a structure thatclearly expresses solar technology andBIPV principles. Funded by DOE FEMP,this structure will serve as an outdoorclassroom and as part of the school’sHVAC circulation system. It will also be ahands-on laboratory for educating peopleabout BIPV systems and training them insystem installation.

Special Design ConsiderationsThe installation is designed to minimizethe cost of the support structure whileincorporating sustainable constructionmaterials. Within an enforced simplicity,the design attempts to establish a con-nection with Navajo building traditions.

PV System ConfigurationThe design includes two 25-ft x 25-ft,open-sided, timber-framed structures.Each one supports 2.88 kW of semitrans-parent PV modules, and each oneincludes two Trace 2.5-kW inverters plusbatteries for three days’ worth of energystorage. Each structure will function as anopen-air classroom.

PV Mounting and AttachmentDetailsThe PV modules are attached with alu-minum extrusions fixed with silicone tothe back of the glass (four per module).Each aluminum channel is 12 ft long. Thechannels are supported on a grid of roughtimber beams, which in turn are sup-ported by timber columns on concretefoundations.

design briefs: Navajo Nation Outdoor Solar Classroom 41

The design attempts to establish a connection with Navajo building traditions.

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42 design briefs: General Services Administration, Williams Building

General Services Administration, Williams Building

The nine-story Williams Building in Boston (at right in photo above) has a new BIPV roof(bottom, lower right photo) rather than aconventional one.

Location: 408 Atlantic Avenue, Boston, Massachusetts

Owner: U.S. General Services Administration

Date Completed: September 30, 1999

Project Developers: Enron Energy Services and U.S. General Services Administration

Electrical Engineer: PowerLight Co.

Solar Consultant: PowerLight Co.

Tradesmen Required: Electricians and roofers

Applicable Building Codes: Standard building codes

Applicable Electrical Codes: National Electric Code, Boston Electric Interconnection Guidelines, and IEEESpecifications

PV Product: PowerLight, using ASE Americas, Inc., solar panels

System Size: 37 kW DC, 28 kW AC

Projected System Electrical Output: 50,000 kWh/yr

Gross PV Surface Area: Approx. 3,800 ft2

PV Weight: 4 lb/ft2

PV Cell Type: Amorphous silicon

PV Efficiency: 12%

PV Module Manufacturer: ASE Americas, Inc.

Inverter Number and Size: 1 30 kVa

Inverter Manufacturer: Trace Engineering

Interconnection: Utility-Grid-Connected

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Description In this project, a regularly scheduled roofreplacement was upgraded to the installa-tion of a building-integrated photovoltaicroof. The BIPV roof is installed on theWilliams Building in downtown Boston.The U.S. Coast Guard is the leading tenantof this 160,000-ft2 building, which sits onRowe’s Wharf at 408 Atlantic Avenue, nearthe city’s financial district.

In addition to the new PV system for theroof, the building is also switching fromdistrict steam to on-site gas boilers. Two75-kW Teco-gen co-generation units arealso being added, as well as a high-efficiency chiller, more efficient lighting,and upgraded, more efficient motors.

Special Design ConsiderationsThe building is located on a wharf, so thedesign must take into account not onlythe water but also 140-mile-per-hour windconditions at the site.

After a site review, including a review ofthe wind conditions, the contractordecided to use a PowerLight RT photo-voltaic system. The RT system was chosenfor its cost-effectiveness when extremeroof penetrations are required (for exam-ple, with penthouses, skylights, and HVACframes).

PV System ConfigurationThis system produces 37 kWp DC and28 kW AC. Its 372 PV panels are con-nected in sets of 12. Each panel has amaximum output of 100 watts.

PV Mounting and AttachmentDetailsA metal raceway, ballast, and anchoringsystem is used. It was also necessary toadd rigid insulation for thermal protection.

The PowerLight RT system is fastened tothe roof along its perimeter using epoxy-embedded anchors set into the concretedeck. These use pitch pans and a racewayfor moisture protection. The systemallows water to flow under thePowerGuard to existing roof drains. Itshould not be necessary to add newdrains.

A harness from the panels goes throughtwo conduits into attic space locatedabove the eighth floor. Part of the atticneeded additional metal decking.

design briefs: General Services Administration, Williams Building 43

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View of the new BIPV roof onthe Williams Building, duringand after construction

Pavers are in foreground, PV array is in background onthe rooftop.

Wiring for the rooftop installationPaul King, DOE Boston Regional Office FEMPliaison, surveys the installation work.

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44 design briefs: General Services Administration, Williams Building

The plan for the roof of the Williams Building included a rooftop BIPV system consisting of 372 solar panels.

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design briefs: Academy of Further Education 45

Academy of Further Education

The Academy of Further Education under construction in Herne, Germany

Location: Herne, North Rhine-Westphalia, Germany

Owner: EMC, Ministry of Interiors of North Rhine-Westphalia, City of Herne

Date Completed: May 1999

Architect & Designer: Jourda et Perraudin Architects, HHS Architects

Structural Engineers: Schleich, Bergermann and Partner

Electrical Engineers: HL-Technik

Tradesmen Required: Glaziers, electricians

PV Product: BIPV roof

Size: 1 MWp

Projected System Electrical Output: 750,000 kWh/yr

Gross PV Surface Area: 10,000 m2

PV Weight: 130 kg per each 3.2 m2 module

PV Cell Type: Polycrystalline and monocrystalline silicon

PV Efficiency: 12.8% to 16%

PV Module Manufacturer: Pilkington Solar International, Cologne

Inverter Number and Size: 600, 1.5 kW

Inverter Manufacturer and Model: SMA, Kassel

Interconnection: Utility-Grid-Connected

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DescriptionAs part of the International ConstructionExhibition, Emscher Park, the site of a for-mer coal mine in Herne, Germany, is beingused for a new purpose. A comprehensiveurban development plan is providing thedistrict of Sodingen with a new center-piece: the Academy of Further Education,Ministry of Interior, North Rhine-Westphalia.

The large glass hall incorporates not onlythe Academy but also a hotel, library, andadministrative municipal offices. Theglass hall is multifunctional. It protectsthe interior from harsh weather and usessolar energy both actively and passivelyby producing heat as well as electricpower.

Special Design ConsiderationsApproximately 3,180 multifunctional roofand facade elements are the core of thesolar power plant. With a total area of10,000 square meters, most of the roofand the southwest facade is covered byphotovoltaics, making this system thelargest building-integrated PV powerplant in the world. It produces approxi-mately 750,000 kWh of electric power per year. This is enough to supply morethan 200 private residences. About200,000 kWh is used directly by theAcademy building, and the remaining550,000 kWh is fed into the public powergrid in Herne.

PV System ConfigurationThe Optisol photovoltaic elements wereproduced by Pilkington Solar at a site inGermany. The PV system consists of solarcells embedded between glass panes.Daylighting needs were taken intoaccount in designing the roof- and facade-integrated system. The PV modules haveareas of 2.5 to 3.2 square meters and anoutput of 192 to 416 peak watts each. Thismakes them larger and more powerfulthan most conventional solar modules.

Direct-current electricity is converted to230 V alternating current by means of a modular inverter. This is made up ofroughly 600 decentralized string invertersand allows optimal use of the incidentsolar radiation.

Mounting and AttachmentDetailsThe building-integrated photovoltaic panels are set into aluminum mullionslike skylights. The rooftop panels arepositioned at an angle to capture as muchof the incident sunlight as possible.

46 design briefs: Academy of Further Education

An inside view of the Academy building as construction progressed

This photo shows how the PV panels are angled to capture the sunlightshining on the roof.

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design briefs: Academy of Further Education 47

Rooftop view shows placement of insulation and PV panels.

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48 design briefs: Discovery Science Center

Discovery Science Center

Architect’s renderingof the DiscoveryScience Center Cubein Santa Ana,California

Location: Santa Ana, California

Scheduled Completion Date: November 1999

Architect & Designer: Arquitectonica for the cube, Solar Design Associates for the PV system

Structural Engineers: Advanced Structures, Inc.

Electrical Engineers: Solar Design Associates, Inc.

Tradesmen Required: Electricians

Applicable Building Codes: Building Administrators Code Administrators International (BOCA)

Applicable Electrical Codes: National Electric Code

PV Product: Thin-film photovoltaic system

Size: 20 kWp

Projected System Electrical Output: 30,000 kWh/yr

Gross PV Surface Area: 4,334 ft2

PV Weight: 3 lb/ ft2

PV Cell Type: Thin-film technology

PV Efficiency (%): 5.1 %

PV Module Manufacturer: BP Solarex

Inverter Number and Size: 4

Inverter Manufacturer and Model: Omnion 2400, Model 5015

Interconnection: Utility Grid-Connected

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Description This solar electric system, located inSanta Ana, California, boasts one of theworld's largest building-integrated thin-film applications to date. The PV-coveredsurface of the cube is tilted at 50° for maximum visual impact and optimal solarharvest. BP Solarex's Millennia modulescover the entire 4,334-ft2 top of the cubeThe thin-film modules are treated as an

architectural glazing element, replacingwhat would have been a glass canopy.They produce up to 20 kW of DC electricityat mid-day and 30,000 kWh of electricalenergy per year, which is enough to runfour typical homes.

The solar energy system is connected to the Discovery Science Center's mainutility line. When the solar system pro-duces energy, it feeds the energy to the

Science Center, displacing conventionalutility power. When the solar system produces more electricity than theScience Center needs, the excess elec-tricity is "exported" to the utility, therebyeffectively spinning the electric meterbackwards.

design briefs: Discovery Science Center 49

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50 design briefs: Solar Sunflowers

Solar Sunflowers

These Solar Sunflowerstrack the sun to produceelectricity.

Location: Napa, California

Date Completed: N/A

Architect & Designer: Solar Design Associates, Inc.

Structural Engineers: Solar Design Associates, Inc.

Electrical Engineers: Solar Design Associates, Inc.

Tradesmen Required: Electricians

Applicable Building Codes: Building Officials Code Administrators International (BOCA)

Applicable Electrical Codes: National Electric Code

PV Product: BP Solarex

Size: 36,000 Wp

Projected System Electrical Output: N/A

Gross PV Surface Area: 3,456 ft2

PV Weight: 3.4 lb/ ft2

PV Cell Type: Polycrystalline

PV Efficiency: 11.1%

PV Module Manufacturer: BP Solarex

Inverter Number and Size: 6

Inverter Manufacturer and Model: Omnion Series 2400, Model 6018

Interconnection: Utility-Grid-Connected

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Description Nestled atop a hillside in NorthernCalifornia, 36 Solar Electric Sunflowersrepresent an elegant combination of artand technology. The clients requested anunconventional and artistic installation.They got just that.

Just like a sunflower, the Solar ElectricSunflowers look and act like nature's ownvariety. Making use of a two-axis trackingsystem, the sunflowers wake up to followthe sun's path throughout the day,enabling the system to produce enoughenergy for eight to ten homes.

design briefs: Solar Sunflowers 51

Solar electric sunflowers resemble nature’s own.

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52 design briefs: Ijsselstein Row Houses

Ijsselstein Row Houses

Fourteen planned new row-house units in the Netherlands demonstrate the aesthetic use ofbuilding-integrated photovoltaics: front (above) and back views.

Location: Ijsselstein Zenderpark, Ijsselstein, The Netherlands

Date Completed: Scheduled for completion in late 2000

Architect & Designer: Han Van Zwieten, Van Straalen Architecten, co-designer; Gregory Kiss, Kiss + Cathcart Architects, co-designer

Structural Engineers: N/A

Electrical Engineers: N/A

Tradesmen Required: Building tradesmen

Applicable Building Codes: Dutch Building Code

Applicable Electrical Codes: Dutch Electrical Code

PV Product: Standard-size BIPV glass laminate panels

Size: 1.6 kWp per housing unit

Projected System Electrical Output: 1150 kWh/year per housing unit

Gross PV Surface Area: 30 m2 per housing unit

PV Weight: 3.75 lb/ft2

PV Cell Type: Amorphous silicon, both opaque and 15% translucent

PV Efficiency: 6%

PV Module Manufacturer: EPV

Inverter Number and Size: N/A

Inverter Manufacturer and Model: N/A

Interconnection: Utility-Grid-Connected

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DescriptionThis Dutch-American design collaborationis intended to develop a new standard inEurope for moderately priced housingwith integrated solar electric systems. Thefirst phase consists of 14 row-house units,each with its own grid-connected BIPVarray. As part of a highly ordered "newtown" development adjacent to the citycenter of Ijsselstein, these units conformto strict space and budget guidelines as well as to advanced standards of PVintegration.

The overall design is a composition ofbrick volumes and two-level, wood-framed sunrooms. The latter are partiallyclad in opaque and translucent PV units,and they are raised and staggered to maximize solar exposure. The sunroomvolumes are wood-paneled on the sidesfacing north.

The Netherlands is home to some of themost advanced PV systems in the world.However, before this project began, littlework had been done on integrating solararrays into the prevailing Dutch architec-tural idiom of abstract cubic forms. TheIjsselstein row houses demonstrate howphotovoltaics can be a fully participatingelement in the design, rather than just an applied system. Amorphous siliconmodules in particular are generating very

positive responses among many Dutcharchitects, who perceive them as lookingmuch more like an architectural materialthan polycrystalline panels do.

Special Design ConsiderationsIn marked contrast to the United States,The Netherlands favors residential designthat is largely modern and rational incharacter. The ubiquitous pitched roofs of North American houses (which provideconvenient mounting surfaces for PVarrays) were considered aestheticallyundesirable at Ijsselstein. However, athigher latitudes with low sun angles, ver-tically mounted BIPV panels can generatepower at output levels competitive withthose of optimally angled panels. Thedesign takes advantage of this by usingstandard-sized units as glazing and exterior enclosure combined in a simplewooden frame wall.

Extensive computer modeling studieswere done to ensure that the complexmassing of the row houses works to pro-vide maximum solar exposure for eachunit’s array and minimum shadowing ofBIPV surfaces by adjacent units.

Given that BIPV glass is a major claddingcomponent for the sunroom elements,excessive interior heat loss or gain was a significant design consideration. Theadjacent stair serves as a convection

chimney that actually uses the heated air produced in the sunrooms to draw aircurrents through the entire row house,cooling it in warm weather. Cold weatherconditions are addressed simply by providing a suitable layer of insulationbetween the cladding and the interior finish.

PV System ConfigurationA 1.6-kW, grid-connected BIPV system ispart of each row house. Each system willbe individually metered, and there is nobattery storage.

PV Module Mounting andAttachment DetailsStandard PV modules are set into a woodframing system, which can be either site-built or prefabricated. The opaque unitsare set as typical single glazing, usingminimum-profile glazing stops and caulk.The translucent panels are incorporatedinto double-glazed window units. The horizontal members of the wood framehave an absolute minimum exposeddepth to prevent shadowing. The verticalmembers, which are not as likely to inter-fere with solar exposure, have a raisedprofile.

design briefs: Ijsselstein Row Houses 53

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54 design briefs: Denver Federal Courthouse

Denver Federal Courthouse

The U.S. Court House expansion in Denver will be a showcase for sustainable building design.

Location: Denver, Colorado

Owner: U.S. General Services Administration

Date Completed: Scheduled for completion in 2002

Architect & Designer: Anderson Mason Dale (Architects); Hellmuth, Obata, & Kassabaum, St. Louis (Designers); Architectural Energy Corporation (Energy Consultants)

System Integration: Altair Energy (PV Consultant)

Structural Engineers: Martin/Martin, Inc.

Electrical Engineers: The RMH Group, Inc.

Tradesman Required: Building tradesmen/glaziers

Applicable Building Codes: Uniform Building Code (1997)

Applicable Electric Codes: National Electric Code (1999)

PV Product: Custom-sized BIPV glass laminate

Size: 15 kWp (roof ); 3.4 kWp (skylight)

Projected System Electrical Output: 20,150 kWh per year (roof ); 4,700 kWh per year (skylight)

Gross PV Surface Area: 172 m2 (roof ); 59 m2 (skylight)

PV Module Weight: 4,661 kg (roof ); 2,749 kg (skylight)

PV Cell Type: Single- or polycrystalline silicon

PV Efficiency: 10% or greater

PV Module Manufacturer: Pilkington Solar

Inverter Number & Size: One 20-kW and one 3.4-kW inverter

Suggested Inverter Manufacturers: Trace Technologies, Trace Engineering, Omnion

Interconnection: Utility-Grid-Connected

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DescriptionThe United States Courthouse Expansionin Denver, Colorado, consists of 17 newcourtrooms and associated supportspaces for an additional 383,000 ft2

(35,600 m2). The U.S. General ServicesAdministration (GSA) approached theexpansion of this Federal Courthouse indowntown Denver as a showcase buildingfor sustainable design. One of the GSA’sproject goals was to "use the latest avail-able proven technologies for environmen-tally sensitive design, construction, andoperation. It should set a standard and bea model of sustainable design." Anothergoal was to create a building that wouldremain usable for its 100-year lifespan.

The design projects an image of respectand reflects the city’s rich architecturalheritage. The 11-story structure houses six floors of district courts, two floors ofmagistrate courts, offices for the UnitedStates Marshal, a jury assembly area,

and a special proceedings courtroom.Anderson Mason Dale P.C. is the architectof record, and HOK served as the designarchitect.

Recalling a traditional town square courthouse, the two-story pavilion is anarrangement of two geometric formsunder a large horizontal roof. It is the frontispiece of the entire composition. An open peristyle colonnade supports the roof and transparently encloses theentrance lobby and the drum-shapedsecured lobby. As a series of vertically oriented rectangular planes, the

courthouse tower caps the structure with an open framework and a floatinghorizontal roof of photovoltaic panels.

With technical assistance provided byFEMP, the project’s sustainable designconsultant, Architectural Energy Corpora-tion of Boulder, Colorado, and the designteam developed the building’s overall sustainable design strategies. The build-ing achieves a high level of energy effi-ciency through a combination ofstrategies that seek first to reduce build-ing energy loads as low as possible andthen to satisfy the remaining reduced

design briefs: Denver Federal Courthouse 55

This chart summarizes the BIPV system design:Component Orientation Effective Size Annual

Area (m2) (kW) kWh

Roof area Horizontal 173.4 13.9 23,300

Lobby skylight Horizontal 63.6 4.4 7,400

Photovoltaics will be integrated into the top roof louver of the tower and into a skylight above the lobby rotunda.

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Standard SkylightGlazing

InsulatedPhotovoltaicGlass

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loads through state-of-the-art, high-efficiency mechanical and electrical sys-tems and renewable energy sources. Theunique attributes of the Denver climate,sunny skies and low humidity, are usedthroughout the design to minimize energyconsumption. The resulting building is a visible expression of sustainabilitythrough features that work together in an integrated energy-efficient system.

The improved building envelope allowssubstantial reductions in energy use forlighting, ventilation, and cooling. Thesereductions, along with the energy gener-ated from the BIPV system, will make theannual operating energy costs of the newcourthouse 43% lower than those of abuilding designed according to Depart-ment of Energy standards for energy efficiency (10 CFR Part 436, which isbased on ASHRAE 90.1-1989).

Energy savings were calculated by con-structing a simulation model of the build-ing that meets the minimum requirementsof the Federal Energy Standard (10 CFRPart 435). This minimally compliant build-ing (the base building) was the baselinefrom which energy savings were calcu-lated. A comparison of the simulatedannual energy costs for the base buildingand the proposed design is shown below.

Local materials, such as precast concreteand native stone, have been incorporatedinto the exterior cladding system. Thebuilding will have a steel frame with recy-cled material content. Most of the flooringmaterials in the building are made fromrecycled or native sources, includingnative stone, cork, or recycled plastics.Low-impact landscaping is used to mini-mize water use, reduce the "urban heatisland" effect, and provide an attractiveoutdoor space. Low-flow lavatory faucetsand water closets will be used throughoutto minimize water use. All interior finishmaterials were carefully selected on thebasis of their impacts on the environmentand occupants.

The building is crowned by a series ofglazing-integrated PV modules incorpo-rated into the top horizontal roof louver ofthe tower and the skylight element abovethe cylindrical volume of the secure lobbyrotunda. This bold architectural statement

expresses both energy efficiency andadaptation to climate. The glazing-integrated PV array at the top horizontalroof louver of the tower is composed ofcrystalline cells covering approximately87% of the visible glazing area. This isintended to be a highly visible element ofthe building’s architecture, recognizablefrom many places around the city.

The cylindrical volume of the secure lobbyrotunda culminates in an insulated BIPVglass skylight using crystalline cells cover-ing approximately 60% of the visible glaz-ing area; it provides necessary shadingwhile generating power for the buildingand making a statement about alternativeenergy sources. Perimeter skylightsaround the outside of the rotunda arelaminated glass. Setting the tone for other special places within the building, a perforated metal scrim ceiling diffusesthis light.

The BIPV panels provide electricity duringdaylight hours, reducing the building’speak electricity requirements. Direct cur-rent from the BIPV system is fed into thebuilding’s electrical system via a DC to ACpower-conditioning unit. Since the systemis utility-interconnected, battery storageis not necessary. Estimated total energyproduction from the two systems isapproximately 25,000 kWh per year, orabout 2% of the building’s total annualelectrical consumption.

The new U.S. Federal Courthouse expan-sion lends an optimistic, forward-lookingimage to the City of Denver while makinga strong case for sustainable design.Inside the courthouse, the design will project a bright, airy appearance. "Green"design features also improve the workenvironment, which can lead to increasesin employee productivity and satisfaction.

By investing in improved materials andsystems, and using an integrated, envi-ronmentally conscious design approach,the GSA will reduce environmentalimpacts as well as long-term operatingcosts. Because the courthouse expansionhas been designated a "demonstrationproject" by GSA, it will be used to influ-ence future courthouse design projects.

Special Design ConsiderationsThe basic laminated BIPV glazing panelsare a compilation of square polycrystalinecells measuring 125 mm x125 mm. Themanufacturing process varies the densityand coverage of these cells within theBIPV panel to accommodate the designintent. This ability to custom-design indi-vidual BIPV panels allowed the designteam to specify skylight panels to be morelight transmissive, thereby providingample illumination of the lobby rotunda,and to design the roof louver panels withgreater opacity, thereby providingincreased power capabilities.

The laminated BIPV glazing panel of theskylights allows the phototvoltaic systemto be responsive to indoor safety andsecurity requirements. Condensation con-cerns also required that the skylight’sBIPV panels be integrated into an insu-lated glazing element.

In addition, the inside glass pane is lami-nated with a milk-white, PVB (polyvinylbutyral) inner layer to diffuse direct sun-light and obscure the less visually appeal-ing side of the crystalline cells from view.

PV System ConfigurationA one-line electrical schematic is given for the two photovoltaic systems. Thephotovoltaic modules are wired in seriesand parallel to meet the voltage and cur-rent input requirements of the power conditioning unit (PCU). To simplify thewiring between the PV array and the PCU,combiners are installed near the array.The array combiners include reverse current protection, surge protection, and series string fusing, and they providea convenient place for testing andtroubleshooting the PV array.

DC and AC disconnects enable proper disconnection and protection for the PCU.Depending on whether the output of thePCU is compatible with utility voltage andgrounding requirements, an external (tothe PCU) isolation transformer may beneeded. A utility-required relay mecha-nism provides over- and under-frequencyprotection and over- and under-voltageprotection. The utility disconnect is aredundant measure required by the utilityto ensure that the PV system will not

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backfeed utility lines that are not meantto be energized. The PCU has an anti-islanding feature that is the first line ofdefense against undesired backfeed onto the utility grid. The point of intercon-nection can be made in any electrical distribution panelboard with the propervoltage and current ratings.

Because the BIPV arrays are located indifferent places on the building, eacharray will be equipped with its own dataacquisition system. The data acquisitionsystems will measure and record fourparameters that can be used to scrutinizethe performance of the BIPV systems.These parameters are the four required by the Utility Photovoltaic Group (UPVG)for its monitoring and rating program.This may also make the PV systems eligible for cost-sharing with UPVG. Thefollowing measurements and sensors will be employed:

(1) Plane-of-array global solar irradiance(W/m2) will be measured with a Licorpyranometer mounted on the array.

(2) Wind speed (m/s) will measured withan NRG systems cup anemometermounted near the array.

(3) Ambient temperature (°C) will be measured with a thermistor inside a radiation shield mounted near thearray.

(4) PV system AC power/energy output(kW/kWh) will be measured with astandard accumulating energy meterwith a special pulse output device.This device will be located near thePCU.

The data from the two data acquisitionsystems will go to a central computer viastandard telephone wire. The computerwill probably be in a busy area, such asthe special proceedings lobby, to helpeducate the general public about BIPVsystems. The computer will have custom-designed software for displaying the datain a "cockpit" format (i.e., with graphicelements such as dials and strip charts).Both real-time and archived data will be

available on this display, along with educational screens.

PV Module Mounting andAttachment DetailsThe glazing-integrated PV modules will be shipped to the site individually withterminals for making electrical connec-tions. Because the skylight installer willmount the modules into the mullions andmake the electrical connections, the elec-trical connections must be very simple.Electrical terminals are located on thepanel edges so they are concealed by the mullion system. Traditional moduleshave a junction box mounted on the back.Special plug-and-socket connectors willenable easy one-wire connections to bemade between adjacent modules. Themullions will be constructed so that indi-vidual modules may be removed forrepairs.

design briefs: Denver Federal Courthouse 57

Insulated Photovoltaic Glass

Standard Skylight Glazing

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Tower BIPVRoof Louver

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These drawings show the position of BIPV modules on the skylight and the tower roof louver.

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BIPV BasicsPhotovoltaic TechnologiesA French physicist, Alexandre EdmondBecquerel, was the first to record hisobservation of the photovoltaic effect(photo denotes light and voltaic denotesthe generation of electricity) in the 19th

century. Since then, many scientistshave worked to develop energy tech-nologies based on this effect. It is aprocess in which electricity is generatedin the boundary layers of certain semi-conductor materials when they are illuminated. Today�s photovoltaic semi-conductor materials include silicon,gallium arsenide, copper indium dise-lenide, cadmium sulfide, and cadmium telluride.

Photovoltaic materials are classified aseither crystalline, polycrystalline, orthin-film in form. These classificationsrepresent the three major PV technolo-gies. These are the building blocks fortoday's commercial PV products, which include consumer electronics(such as a solar-powered calculator orwatch), remote electric power systems,utility-connected power systems, andbuilding-integrated systems.

One of these PV materials, silicon, ishighly abundant; it constitutes morethan 25% of the Earth's crust. Silicon isused in more than 90% of all PV appli-cations, including building-integratedphotovoltaics or BIPV. Silicon solartechnologies can be grouped in thesethree basic areas: single-crystal silicon,polycrystalline silicon, and thin-film amorphous silicon. The primary dis-tinctions among the three technologiesare their sunlight-to-electricity conver-sion efficiency rates, the methods bywhich they are manufactured, and theirassociated manufacturing costs.

The efficiency of each BIPV product is specified by the manufacturer.Efficiencies range from as low as 5% to as high as 15%�16%. A technology'sconversion efficiency rate determinesthe amount of electricity that a com-mercial PV product can produce. Forexample, although thin-film amor-phous silicon PV modules require lesssemiconductor material and can be lessexpensive to manufacture than crys-talline silicon modules, they also havelower conversion efficiency rates. Untilthese conversion efficiencies increase,

58 BIPV Basics

Cell

Module

Panel

Array

02527265m

PV CellsPV cells are the basic building blocksof PV modules. They are made of semi-conducting materials, typically silicon,doped with special additives. Approx-imately 1/2 volt is generated by eachsilicon PV cell. The amount of currentproduced is directly proportional tothe cell’s size, conversion efficiency,and the intensity of light. As shown inthe figure below, groups of 36 series-connected PV cells are packagedtogether into standard modules thatprovide a nominal 12 volt (0r 18 volts@ peak power). PV modules were originally configured in this manner to charge 12-volt batteries. Desiredpower, voltage, and current can beobtained by connecting individual PVmodules in series and parallel combi-nations in much the same way as batteries. When modules are fixedtogether in a single mount they arecalled a panel and when two or morepanels are used together, they arecalled an array. (Single panels are alsocalled arrays.)

Photovoltaic device 02527264m

Lightenergy

Electricalenergyp-Type

semiconductor

n-Typesemiconductor

The Photovoltaic EffectSunlight is composed of photons—discrete units of light energy. When photonsstrike a PV cell, some are absorbed by the semiconductor material and the energy is transferred to electrons. With their new-found energy, the electrons can escapefrom their associated atoms and flow as current in an electrical circuit.

PV arrays require no care other than occa-sional cleaning of the surfaces if they becomesoiled or are used in dusty locations. However,they must be kept clear of snow, weeds, andother sources of shading to operate properly.PV cells are connected in series, so shadingeven one cell in a module will appreciablydecrease the output of the entire module.

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more amorphous silicon modules willbe required to generate the sameamount of electric power produced byother silicon-based PV modules.Continuing research and developmentin thin-film silicon should increase itsconversion efficiencies.

An important architectural considera-tion is aethetics, and PV modules dodiffer in appearance. Single-crystallinePV modules are dense blue (almostblack), with a flat, uniform appearance.Polycrystalline modules are multicol-ored, having a variety of sparkling bluetones. Thin-film amorphous silicon

modules are a reddish-brown to black;the surface may appear uniform ornonuniform, depending on how themodules are made. Consequently, typical system colors are blues, browns,and black. However, some PV manu-facturers can fill special orders for col-ors such as gold, green, and magenta.These color variations will result insome loss in performance efficiencies.

BIPV SystemsPV applications for buildings beganappearing in the United States and else-where in the 1970s. Aluminum-framed

PV modules were connected to, ormounted on, buildings that were usu-ally in remote areas without access toan electric power grid. In the 1980s, PV module add-ons to roofs beganbeing demonstrated. These PV systemswere usually installed on utility-grid-connected buildings in areas with cen-tralized power stations. In the 1990s,BIPV construction products speciallydesigned to be integrated into a build-ing envelope became commerciallyavailable.

Internationally, the past decade hasushered in a myriad of BIPV demon-stration buildings and other structures.In both new projects and renovations,BIPV is proving to be an effective building energy technology in residen-tial, commercial, industrial, and institu-tional buildings and structures.

BIPV systems are considered to be multifunctional building materials, and they are therefore usually designedto serve more than one function. Forexample, a BIPV skylight is an integralcomponent of the building envelope, a solar energy system that generateselectricity for the building, and day-lighting element.

The standard element of a BIPV systemis the PV module. Individual solar cellsare interconnected, encapsulated, lami-nated on glass, and framed to form amodule. Modules are strung together in an electrical series with cables andwires to form a PV array. Direct or dif-fuse light (usually sunlight) shining onthe solar cells induces the photovoltaiceffect, generating unregulated DC elec-tric power. This DC power can be used,stored in a battery system, or fed intoan inverter that transforms and syn-chronizes the power into AC electricity.The electricity can be used in the build-ing or exported to a utility companythrough a grid interconnection.

BIPV systems are made up of BIPV construction materials and balance-of-system (BOS) hardware. The BOS hard-ware is composed of cabling, wiring,and structural elements that hold the modules in place, as well as

BIPV Basics 59

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Schematic of a typical stand-alone PV system

PV array

Lightningprotection

Sourcecombinerwith DCstring

disconnects DC

UIDC/ACinverter

ACdisconnect

Utility serviceconnection

kWhmeter

Electricaldistribution

panel

AC to allloads

AC

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Block diagram of a utility-interactive PV system

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grid-metered connections, fault pro-tectors, a power conditioning unit(inverter), and an electricity storagesystem (usually batteries), as needed.

Demonstrations of BIPV systems havegreatly increased people's awareness of the potential of BIPV products. This is especially true for members of thebuilding profession and constructiontrades. At the same time, the PV indus-try has gained experience in designing,manufacturing, and installing BIPVsystems. The current challenge for theindustry is to penetrate the commercialconstruction market. This is beingachieved through new linkagesbetween PV manufacturers and thebuilding materials manufacturingindustry.

The economics and aesthetics of BIPVsystems are optimized when PV is integrated into the building during pre-liminary design stages. In order to beeffective, BIPV products should matchthe dimensions, structural properties,qualities, and life expectancy of thematerials they displace. Like standardconstruction glass, cladding, and roof-ing materials, they can then easily beintegrated into the building envelope.

Design IssuesBeyond comfort and aesthetics, BIPVdesign considerations encompass bothenvironmental and structural factors.Environmental factors include a struc-ture's solar access as well as averageseasonal outdoor temperatures at thesite, local weather conditions, shadingand shadowing from nearby structuresand trees, and the site's latitude, whichinfluences the optimum BIPV systemorientation and tilt. Structural factorsinclude a building's energy require-ments, which influences the size of thesystem, and the BIPV system's opera-tion and maintenance requirements.These factors must all be taken intoaccount during the design stages, whenthe goal is to achieve the highest possi-ble value for the BIPV system. Some ofthe major design considerations uniqueto solar energy systems are solar access,

system orientation and tilt, electricalcharacteristics, and system sizing.

Solar access � Solar access, the inci-dence of solar radiation (insolation)that reaches a PV surface at any giventime, determines the potential electricaloutput of a BIPV system. Solar radiation data for sites in the UnitedStates can be obtained from theDepartment of Energy's NationalRenewable Energy Laboratory (NREL).The data are available in publicationssuch as the Solar Radiation Data Manualfor Flat-Plate and Concentrating Collectorsand the Solar Radiation Data Manual forBuildings (call (303) 275-4363 to requestcopies) or online from the RenewableResource Data Center (http://rredc.nrel.gov). Statistical estimations ofaverage daily insolation levels for spe-cific locations are commonly used inthe BIPV design process and measuredas kilowatt-hours per square meter perday (kWh/m2/day).

System Orientation and Tilt � To max-imize solar access and power output,the physical orientation of the BIPVsystem and the tilt angle of the arrayshould be considered relative to thegeographical location of the buildingsite. As a general rule of thumb, BIPVinstallations north of the equator per-form optimally when oriented southand tilted at an angle 15 degrees higherthan the site latitude. Conversely, BIPVinstallations south of the equator per-form best when oriented north andtilted at an angle 15 degrees lower thanthe site latitude. The orientation and tilt may vary from this formula when a BIPV system's particular seasonal performance must be optimized. Forexample, a system might be designed to produce maximum power outputonly in the summer months in order to reduce peak electricity costs for air-conditioning loads; thus, the systemshould be installed at an optimum orientation and tilt for summer poweroutput.

Demonstrations have shown that a sys-tem installed at a tilt angle equivalentto the site latitude produces the greatestamount of electricity on an annual

basis. In comparison to a system's per-formance at latitude angle, annual performance losses for vertical facadesystems can be as high as 30% or more.In contrast, annual performance lossesfor horizontal installations can be ashigh as 10%, in comparison to those ofsystems installed at latitude angle.

Electrical Characteristics � The perti-nent electrical characteristics of a PVmodule or array are summarized in therelationship between the current andvoltage. The amount and intensity ofsolar insolation controls the current (I);the temperature of the solar cells affectsthe voltage (V) of the PV module orarray. Module I-V curves that sum-marise the relationship between thecurrent and voltage are furnished bymanufacturers. I-V curves provideinformation designers need to config-ure systems that can operate as close to the optimal peak power point as possible. The peak power point is mea-sured, under standard testing condi-tions (STC), as the PV module producesits maximum amount of power whenexposed to artificial solar radiation of1000 W/m2.

System Sizing � Choosing a BIPV typeand sizing a system have three maincomponents: energy loads, architecturalor aesthetic considerations, and eco-nomic factors. To determine the desiredpower rating of a BIPV system for abuilding, the electrical requirements ofthe building should first be evaluated.The optimum power rating of the sys-tem can be calculated and sized, basedon the portion of the building's electric-ity that will be supplied by the BIPVsystem. For example, an autonomous oroff-grid building may require a largesystem with battery storage capabilitiesto provide 100% of the building's elec-tricity requirements; a building ownerdesiring to reduce demand charges willrequire a small system that produceselectricity only during peak utilitycharge hours.

Architecturally, the size of the BIPV system is physically limited to thedimensions of the building's availablesurface area. The balance between the

60 BIPV Basics

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amount of power required and theamount of surface area available candetermine the type of PV technologythat will be used. Each technology hasan associated range of output in wattsper square foot or per square meter andcost per watt. For example, systemsmade of amorphous silicon require alarger surface area but cost less thanequivalent systems composed of single-crystal solar cells. Therefore, in projectsthat have a limited budget but include alarge south-facing facade surface area,amorphous silicon can be the most suit-able BIPV technology.To achieve theappearance of a uniform surface area,less expensive "mock" or imitation PVpanels can also be provided by themanufacturer.

Once the building energy load require-ment is determined, the watt-hourmethod can be used to design the elec-trical system. An evaluation of seasonalclimatic conditions and variations (tem-perature and solar insolation) and theavailable surface area will determinethe number of modules that will satisfythe voltage and current requirement of the load. After that, correspondinginverter requirements and BOS require-ments can be specified. Currently, PVspecialists, system integrators, and consultants provide electrical sizinginformation, assessments, and recom-mendations. However, BIPV manufac-turers are increasingly providing fullturn-key services for large systems for commercial buildings, and prepack-aged, standardized, residential systemsare being sold by distributors. For moreinformation on software tools for opti-mizing PV systems, see Appendix B.

Electrical and Safety IssuesElectrical issues primarily involve theperformance and reliability of theinverters. The variety available forBIPV systems include single inverters,master-slave inverter configurations,modular inverters, and parallel-independent or string inverters. ABIPV system is most vulnerable to asingle-point failure where the powergenerated from the BIPV array must betransformed and synchronized through

the inverter from DC to AC power andthen fed into the building or an electricutility system. If the inverter fails, theentire system malfunctions.

Today, most inverters are highly reli-able. However, the practice of relyingon only one inverter for a BIPV systemin a commercial building is problem-atic. When BIPV systems are made up of a large series of interconnectedstrings, there is a technical difficulty indetermining where a system has failed.This is akin to the problem people hadwith old-fashioned Christmas treelights. When one light malfunctioned,the entire string went down, and eachbulb had be tested to determine thesource of the problem.

A BIPV system designed so that multi-ple inverters work together ensuresgreater system reliability. If one invertermalfunctions or requires maintenance,it can be disconnected from the arrayand the BIPV system can still operate. A cascading hierarchy "master-slave"configuration includes one masterinverter and multiple slave invertersthat operate together for maximum efficiency

Modular, "micro," or "mini" invertersallow each module to be tested (eachhas its own address) through the use of a power line carrier signal injectedinto the building's electrical distribu-tion system. This way, each unit's performance can easily be evaluated.Modular inverters also enable PV to be integrated into complex, geometricbuilding designs.

Modular inverters are desirable forcommercial buildings because theyoperate independently. Shading onemodule will not interrupt the poweroutput of the whole array. In single ormultiple inverter systems, a number of modules are connected in series toachieve the voltage needed by theselected inverter. Shading any onemodule in this series can negate theoutput of the entire string.

One design issue related to the modularinverter is whether it will last the

lifetime of the PV module. If theinverter has a lifetime of only 5 yearsand the BIPV facade lasts 25 years,replacing the modular inverter has anassociated periodic cost, and accessneeds to be anticipated and designedinto the project.

The string inverter is the second generation of inverters for buildings. In Europe, one string inverter with thenominal power of 750 watts can con-nect as many as 10 PV modules in aseries and be connected anywhere inthe building's electricity distributionsystem. The flexibility, reliability, andincreased efficiency offered by stringinverters may further reduce the cost of BIPV systems.

New AC modules are being equippedwith individual AC mini-invertersmounted on the backs of the PV panels.They are at the early commercial stagesof development in the United Statesand Switzerland. One benefit of these is that they eliminate the need in thebuilding for the high-voltage DCwiring associated with other BIPV systems.

In regard to electrical safety issues, it is important to note that lightning,ground faults, and power line surgescan cause high voltages in otherwiselow-voltage BIPV systems. Nationaland international electric code regula-tions and building codes are beingamended to include PV technologiesand address fire and safety issues con-cerning BIPV design, installation, andmaintenance.

Codes and StandardsThe national model codes historicallyhave been composed of three primaryorganizations: the InternationalConference of Building Officials(ICBO), Building Officials CodeAdministrators International (BOCA),and the Southern Building CodeConference International (SBCCI).These organizations have collaboratedto create one umbrella organization, the International Code Conference(ICC). The ICC has begun the process

BIPV Basics 61

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of writing one model code, the Inter-national Building Codes. These codesbegan development in 1996, and theentire group will be published by theyear 2000. Although these codes mustbe adopted by each municipality tohave any authority, they will be themost up-to-date ones that can beadopted after the year 2000. This is amajor step toward a unifying modelcode, reducing the duplication anddiversity of the previous three codebodies. The change process for all ICCcodes will occur annually until 2003and at three-year intervals after 2003.

To date, these codes do not refer specifi-cally to BIPV systems, leaving compli-ance to the discretion of local buildinginspectors. If BIPV is the structuralequivalent of a current building mater-ial, only specific code provisions orcompliance required for the structuralequivalent will be necessary. However,the typical crystalline PV cell addsweight to the traditional building product relative to a thin filmed glaz-ing, and this may require closer evalua-tion by code officials. Because of theirmultifunctional nature, BIPV systemsmust also comply with the NationalElectric Code (NEC), which addressesPV power systems but not BIPV specifically.

Local codes vary by state and munici-pality, and some covenant-controlledcommunities regulate the appearanceof buildings for architectural aestheticsand homogeneity. This may affect deci-sions about the suitability of BIPV sys-tems. Furthermore, a few communitiesin the United States have developedzoning ordinances relative to solaraccess laws that could affect BIPV sys-tems and structures that may shadesolar systems.

Residential Energy Codes � The ModelEnergy Code (MEC) has been pub-lished by the Council of AmericanBuilding Officials (CABO). The MEC isno longer being updated, and is beingreplaced by the International EnergyConservation Code (IECC). The CABOrequirement for one- and two-familydwellings is being replaced in the year

2000 by the International ResidentialCode. The CABO document is notbeing updated at this time, and changeswill need to be made to the IRC. Thechange process for both the IECC andIRC will occur annually until 2003 andat three-year intervals after 2003.

Commercial Codes & Products � DOEsupports commercial energy codes,especially ASHRAE 90.1, by helping todevelop them and by providing toolsand resources that make the codes easier to use. The COMcheck-EZTMmaterials were developed to simplifyand clarify commercial and high-riseresidential building energy coderequirements. The materials includeeasy to use IBM-compatible software;compliance guides for envelope, light-ing, and mechanical requirements; andprescriptive packages for county-basedclimate zones. Forms and a checklist are included to document compliance.All COMcheck-EZ materials can bedownloaded at no cost. If you down-load any material, please register withthe program so you will be notified ofupgrades (online, see http://www.energycodes.org/comm/comm.htm).

Federal Building Codes � The currentFederal code for low-rise residentialenergy efficiency (10 CFR Part 435, sub-part C) can be obtained online (seehttp://www.access.gpo.gov/nara/cfr/cfr-retrieve.html#page1). DOE has beenupdating this code. The proposed rule-making for the Energy Efficiency Codefor new Federal Residential Buildingswas published in the May 2, 1997, edi-tion of the Federal Register. A printedcopy of the rulemaking can be obtainedin Federal Register Volume 62, Number85, pages 24163-24209, or at the onlineaddress above.

The proposed rule is based on the 1995version of the Model Energy Code, butit contains more stringent enveloperequirements and rules related to radoncontrol and backdrafting from fossil-fuel-burning appliances. DOE has beenpreparing the final rule based on com-ments received on the proposed ruleand expects to issue it in 1999. DOE is also preparing a code compliance

package known as FEDcheck to assistusers in understanding and complyingwith the code. For more information,contact Stephen Walder, DOE, 202-586-9209, or Robert Lucas, PacificNorthwest National Laboratory, 509-375-3789 (online, see http://www.energycodes.org/federal/federal.htm).

DOE has also prepared a third editionof its Building Standards and Guide-lines Program catalogue. This catalogueis one of many services that promotethe adoption, implementation, andenforcement of residential and com-mercial building energy codes. One ofthe primary goals of the program is toprovide products and services thatmake it easy for builders, architects,designers, building code officials, andstate energy officials to implementbuilding energy codes.

The catalogue features many productsthat will quickly and efficiently imple-ment the requirements of the ModelEnergy Code; the American Society of Heating, Refrigerating, and Air-Conditioning Engineers and Illumin-ating Engineering Society of NorthAmerica Standard 90.1-1989; and theFederal Performance Standards forNew Commercial and Multi-FamilyHigh-Rise Residential Buildings.

In addition to the catalogue, theMECcheck and COMcheck-EZ compli-ance tools and manuals may be down-loaded at no cost from the BuildingStandards and Guidelines Web site athttp://www.energycodes.org/. Formore information, or to place an order,call the U.S. Department of EnergyBuilding Standards and Guidelinesprogram hotline at 1-800-270-CODE(online, see http://www.energycodes.org/news/catalog.htm).

State Energy Codes � The status ofeach state�s building energy codes iscurrent as of September 1997. The list islikely to become less accurate in time,however, as states adopt new codes.Thus, there will be continual updates.Printed copies of the State BuildingCodes Database are available for $15 bycalling 1-800-270-CODE. To view the

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status of a particular state�s energycodes, select a state from the list online(see http://www.energycodes.org/states/ states.htm). The status of thestate energy codes can be found athttp://www.bcap.com .

MaintenancePV has no recurring fuel costs, and it is promoted as a simple energy technol-ogy that is durable and relatively main-tenance-free because it has no movingparts. However, designers shouldensure that BIPV installations alloweasy access for inspecting, repairing,and replacing components. Mainten-ance costs can be divided into two cate-gories: preventive and failure-related.

Preventative maintenance can ensurethe performance of a BIPV system.Shadowing on the PV array caused by the natural or built environmentreduces system output. Sunlightreflects off expanses of sand, snow, ice, and other light surfaces, and canincrease output by reflecting additionalsolar energy onto arrays. However,other structures, trees, and bushes neara BIPV system can inhibit solar accessand thus reduce system performance.This is in turn detrimental to the economic performance of the system.

In the case of building retrofits, land-scaping can often shade parts of a roofand limit solar access, so landscapearchitecture must be considered, andtrees must be trimmed periodically.

The electrical performance of a BIPVsystem can also be affected by accumu-lations of dirt on the modules. In mostlocations, normal rainfall removes thelayers of dust and pollution that canaccumulate on the outer surface. Wherethere is little rainfall, occasionallyspraying the system with water from a standard garden hose to remove dirt and debris is adequate but not required.

The performance of a BIPV system candecline if it is located in a particularlydirty urban environment. Layers ofgrime, caused by fuel exhaust and otheremissions, can accumulate on a system.

This exhaust can combine with sun-baked atmospheric dust to reduce theamount of light that can reach the modules and thus reduce system per-formance. Such systems may requireperiodic cleaning with chemical agentsto maximize the system's electrical out-put. Consequently, system designersmust ensure adequate access to the system to perform these maintenanceactivities.

Failure-related maintenance involvesrepairs and replacements associatedwith poor performance or failures ofthe BIPV system. This can be coveredunder traditional and extended warranties.

WarrantiesBIPV systems are generally covered by a limited 12-month replacementwarranty that guards against defectsand ensures system repair and productreplacements or an optional full refundof the purchase price. In case of an acci-dent, such as a fire, ancillary damage toa BIPV system may be covered by aconventional building insurance policy.

Currently, the major PV manufacturersoffer power production warranties foras long as 10, 20, and 25 years. These manufacturers will replace the poweroutput lost from modules that fail toproduce at least 80% of the minimumpower output specified on the back ofthe module. This warranty dates fromthe sale of the product to the originalpurchaser and is generally nontrans-ferrable. Other suppliers also offeroptional warranties on roofing throughservice and maintenance contracts.

BIPV ProductsThese are the types of BIPV systemscommercially available:

Facade systems � The BIPV system isdesigned to act as an outer skin andweather barrier as part of the buildingenvelope. An example is a BIPV systemused for rainscreen overcladding. GlassBIPV products are typically used asfacade systems.

Atrium systems � BIPV is a glass ele-ment that provides different degrees of shading and can be designed toenhance indoor thermal comfort as well as daylighting.

Awning and Shading systems � A vari-ety of PV materials can be mountedonto a facade in aesthetic manner toserve as awnings.

Roofing systems � The BIPV system displaces conventional roofing materi-als such as tiles, shingles, and metalroofing.

The cost of a BIPV system depends on the type of system and the PV technology used in manufacturing it.Currently, only a few U.S. manufactur-ers produce custom and standardizedBIPV products. For commercial andinstitutional structures and buildings,the two primary types of BIPV prod-ucts, facades and roofing materials, areavailable for both new construction andrefurbishment projects.

BIPV Facade Systems � BIPV facadesystems include laminated and pat-terned glass, spandrel glass panels, andcurtain wall glazing systems. TheseBIPV products can displace traditionalconstruction materials. Laminated glassis a standardized BIPV product. It iscomposed of two pieces of glass withPV solar cells sandwiched betweenthem, an encapsulant of ethylene-vinylacetate (EVA) or another encapsulantmaterial, and a translucent or coloredtedlar-coated polyester backsheet. Itcan also be made with only one piece of glass and a tedlar backsheet.Architects can specify the color of thetedlar backsheet.

Spandrel panels are the opaque glassused between floors in commercialglass building facades. A glazed curtainwall is a non-load-bearing exterior wallsuspended in front of the structuralframe and wall elements. Patterned orfritted glass is semitransparent withdistinctive geometric or linear designs.

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Some companies sell custom-madeBIPV glazing products, available in anysize or dimension and consisting of anyPV technology (crystalline or thin film).The architect can indicate the spacingbetween solar cells, which will deter-mine the power supply and also permitthe design of passive solar features byregulating the amount of daylightingallowed to enter into the builiding.These products can be used in any com-mercial glazing application. Standardand custom products are available inmany sizes (as large as 1.3 m x 1.7 m)and in a range of thicknesses (0.5 mm to 2.5 mm glass).

Curtain wall laminates are available forboth AC and DC power. The AC panelhas its own mini-inverter attached tothe back of the laminate. The ACPowerWall� operates with current atmaximum power with 2.0 amps (A)and 110 volts (V). The DC PowerWall�operates at maximum power with 3.5 Aand 68.4 V. The PowerWall� generates250 watts (W) under standard test conditions (STC).

BIPV Roofing Systems � Roofing sys-tems include BIPV shingles, metal roofing, and exterior insulation roofsystems. These BIPV products can dis-place traditional construction materials.

Flexible thin-film amorphous siliconBIPV shingles can replace asphalt shingles. This BIPV product is nailed tothe roof deck, very much the way thattraditional asphalt shingles are attachedto a roof. This technology was designedas a 2-kilowatt peak (kWp) BIPV sys-tem for the Southface Energy Institutein Atlanta, Georgia. Also available are fiber cement PV roofing shinglesmeasuring 16 in. (40 cm) by 12 in.(30 cm) by 1/4 in. (0.6 cm) and weigh-ing 5 pounds (2.27 kg). Crystalline sili-con cells are laminated to fiber cementroofing shingles and are rated at 11 Wof power output under STC.

64 BIPV Basics

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BIPV metal roofing can replace anarchitectural standing seam. The thin-film amorphous silicon PV material islaminated directly onto long metalroofing panels. The BIPV metal roofingpanels, with edges turned up, are laidside by side and a cap is placed over thestanding edges to form a seam. Thesemetal panels can be installed by a tradi-tional roofer followed by an electrician.

As an exterior insulation BIPV roof sys-tem, PV laminates are attached to poly-styrene insulation, and it providesthermal insulation rated R-10 or R-15. It rests on the waterproof membranewithout penetrating or being mechani-cally fastened to the building. In aninterlocking tongue-and-groove assem-bly, the panels are weighed down bypavers that surround the system to provide access for maintenance andrepairs. Channels or raceways aredesigned to provide access to the elec-trical connections. This technology canbe used to redo the roof of an existingbuilding, as demonstrated by the NewYork Power Authority on a communitycenter in Tuckahoe, New York.Additionally, the PV portion of theproduct can be tilted up to 12° to helpoptimize the system's orientation.

This system can be installed on built-up and single-ply membranes of flatcommercial roofs and typically weighs4 lb/ft2 versus 10 lb/ft2 for a conven-tional aggregate ballast roof. Any PVtechnology can be applied in this pro-cess and will provide power accordingto its solar cell and system efficiencyrating.

The manufacturer claims that this product extends normal roof life byprotecting insulation and membranesfrom ultraviolet (UV) rays and waterdegradation. It does this by eliminatingcondensation because the dew point is kept above the roofing membrane.

BIPV Product DevelopmentSince the early 1990s, the U.S. Depart-ment of Energy's (DOE's) Photo-voltaics: Building Opportunities in theUnited States (PV:BONUS) program

has brought together PV and buildingproduct manufacturers in a coordinatedeffort to develop PV roofing shingles,facade glazing, and curtain wall prod-ucts for buildings and other structures.Today there is a recognizable commer-cialization trend toward standardizingBIPV construction products. In the longrun, product standardization will be anessential element in reducing the cost of manufacturing BIPV systems. Thefollowing section on new constructionmaterials for buildings was extractedfrom a paper written by Sheila J.Hayter, P.E. (NREL) & Robert L. Martin(DOE). This paper, titled "Photovoltaicsfor Buildings, Cutting Edge PV," was presented at the UPEX conference in1998. Below is the section on BuildingOpportunities in the U.S. for Photo-voltaics (PV:BONUS).

The U.S. Department of Energy demon-strates its commitment to supportingnew PV-for-buildings technologies byawarding Cooperative Agreementfunding to U.S. manufacturers andorganizations for product develop-ment. These agreements are within theBuilding Opportunities in the U.S. forPhotovoltaics (PV:BONUS) program.The objective of the PV:BONUS pro-gram is to develop technologies and tofoster business arrangements that inte-grate photovoltaics or hybrid productsinto buildings cost-effectively. Cost-effectiveness, either through design;integration (i.e., components, system,and/or building integration); dedicatedend-use applications; or technologybundling (i.e., PV/thermal hybrids) is a major factor in selecting PV:BONUSprojects. DOE is interested in productsthat can replace commercial buildingproducts and be installed without thenecessity for specialized training. Theultimate goal of the PV:BONUS pro-gram is market demonstrations of com-mercially viable products that lead tomanufacturer commitments to pursueproduction and sales.

In 1993, the U.S. Department of Energyawarded cooperative agreements forfive PV:BONUS projects. The success of this initial effort resulted in DOE

funding additional projects in 1997under a second program known asPV:BONUS Two.

PV:BONUS (June 1993 – May 1999). Thefive projects originally funded by thePV:BONUS program have all been suc-cessfully installed in demonstrationprojects, and most are now commer-cially available to the buildings indus-try. These new technologies include thefollowing.

� AC photovoltaic module and curtainwall application (Figure 1)

� Architectural PV glazing system(Figure 2)

� Dispatchable PV peak-shaving system

� PV-integrated modular homes(Figure 3)

� Rooftop BIPV standing-seam systems(Figure 4).

AC Photovoltaic Module and CurtainWall Application. The product devel-oped for this PV:BONUS project was alarge-area PV module with a dedicated,integrally mounted, direct-current (DC)to alternating-current (AC) powerinverter (Figure 1). The module isdesigned to be integrated into the vertical facades and sloped-roof construction of residential, commercial,or institutional buildings. Large spacesbetween the PV cells can be incorpo-rated into the module design to allowdirect sunlight to transmit through themodule. The building designer can usethis feature to enhance daylighting andprovide passive solar heating to thespace adjacent to the modules. SolarDesign Associates, Inc., led develop-ment efforts for this project. Other teammembers included Mobil Solar EnergyCorp., New England Electric, New York Power Authority, Pacific Gas andElectric, Kawneer, Maryland EnergyAdministration, and Baltimore Gas and Electric.

Architectural PV Glazing System. Asystem of matching building facadeglazing products including opaque,

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semitransparent, and clear units wasdeveloped. A large-area, thin-film PVmodule option was available for theopaque and semitransparent units. Thesystem was incorporated into the over-head glazing of a demonstration projectin an Applebee�s Neighborhood Grilland Bar in Salisbury, NC (Figure 2). Thedesigners placed a high-absorptancemetal pan approximately 1 in. (2.5 cm)below the back of the panel to increaseeffectiveness for solar heating of the airbehind the panels. Fans operated by thePV system drew the heated air throughan air-to-water heat exchanger toreduce the restaurant�s energy demandfor producing hot water. Drawing hotair off the back of the PV panels alsoincreased the operating efficiency of the panels. Although the manufacturerof the PV panels and leader of thisPV:BONUS team, Advanced Photo-voltaic Systems (APS), is no longer inexistence, the PV technology the com-pany developed continues to be usedby the PV industry. Innovative Designpartnered with APS to design theApplebee�s system.

Dispatchable PV Peak ShavingSystem. A fully integrated dispatchablepeak-shaving system for commercialapplications was designed for thisPV:BONUS project. The focus of theproject was to reliably control the PVsystem output for a prescribed lengthof time by including battery storagewith the PV system. The dispatchablesystem made it possible to displace aload greater than the array�s outputduring peak demand periods. This fea-ture is especially important in commer-cial buildings where the peak demandperiod often extends beyond the periodof peak power production of the PVsystem. Delmarva Power and LightCompany was responsible for thisPV:BONUS effort.

PV-Integrated Modular Homes.Installing residential photovoltaic sys-tems onto homes constructed in a fac-tory along with other energy-efficientfeatures result in reducing the total construction cost of the manufacturedhomes to be comparable to typical site-built homes (Figure 3). The objective of

this PV:BONUS project was to design a line of modular solar homes thatinclude photovoltaic power. To meetthis objective, it was necessary to mini-mize construction costs of the home sothat the higher cost of the PV systemcould be absorbed into the overall costof the home. The effort was lead byFully Independent Residential SolarTechnologies, Inc. (FIRST, Inc.), a non-profit organization teamed withBradley Builders and Avis America (a builder of manufactured homes).

Rooftop Photovoltaic Systems. Theresult of this PV:BONUS project wasthe development of residential andlight-commercial PV-integrated roofingmaterials. These amorphous-siliconmodules are manufactured either toresemble asphalt shingles or to be lami-nated onto metal standing-seam roofmodules (Figure 4). One of the goals ofthe project was to develop a productthat required no special training toinstall the PV-roof on actual buildings.These products have been tested indemonstration projects and are nowcommercially available. The leader of this development team, EnergyConversion Devices, Inc., worked with United Solar Systems Corp., theNational Association of Home Builders,Solar Design Associates, Inc., and anumber of utility companies, construc-tion companies, government agencies,and educational institutions to design,manufacture, and test this product.

PV:BONUS Two (September 1997 – early2000s). PV:BONUS Two activities arebeing carried out in three phases. PhaseI was the concept development andbusiness planning phase. Prototypesystems will be developed and tested in Phase 2, the product and businessdevelopment phase. Product demon-stration and marketing will occur inPhase 3. It is expected that viable prod-ucts will be offered commercially dur-ing Phase 3. Participation in Phases 2and 3 depend on the accomplishmentsof the previous phases.

The U.S. Department of Energyawarded 17 Phase I cooperative agreements. These project areas were

divided into four categories: 1) glazingproducts; 2) roofing materials; 3) PV/thermal (PV/T) hybrid systems; and4) other related projects (inverter tech-nology, fire retardancy investigations,and development of a "mini-grid"). At the completion of Phase I, seven ofthese projects were selected for contin-ued Phase II funding. Phase II is cur-rently under way and the followingprojects are being pursued:

� PV-powered electrochromic windows

� Thin-film PV product line

� Hybrid PV/thermal collector

� Ballast-mounted PV arrays

� PV string inverters

� Field-applied PV membrane

� PowerRoofTM 2000.

PV-Powered Electrochromic Windows.Sage Electrochromics, in conjunctionwith Solarex, proposes to develop andcommercialize photovoltaic (PV) pow-ered electrochromic (EC) "smart win-dows." EC windows control the amountof sunlight and solar heat by dynami-cally switching between darkened andclear states and anywhere in between.They provide an opportunity to realizeenergy savings and reduce peak electrical demand in buildings. Thelow-power DC voltage required topower the EC window glazing will besupplied by PV solar cells incorporatedin the double-pane insulating glass unit(IGU) so that no external hard-wiredconnections are needed.

Thin-Film Photovoltaics. With the support of subcontractors Kawneer,Solar Design Associates, Inc., andViracon, Solarex will develop building-integrated photovoltaic products usingtandem-junction amorphous siliconmodules. Major objectives of the pro-gram include: 1) developing a commer-cial photovoltaic curtain wall module(Spandrel Module); 2) developing acommercial photovoltaic sunshade forcurtain walls (PowerTint Window); and 3) developing a light-transmitting

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photovoltaic module and incorporatingit into the curtain wall product.

Hybrid Photovoltaic/ThermalCollector. Solar Design Associates, Inc.,United Solar Systems Corporation, and SunEarth, Inc., propose to design,develop, demonstrate, manufactureand commercialize a hybrid flat-platephotovoltaic/thermal (PV/T) collectorto deliver both electricity and thermalenergy. The PV/T collector design will employ a liquid thermal transfermedium and closely resemble conven-tional flat-plate solar thermal collectorsin size, appearance, installation, andfunction. However, in place of the normal thermal absorber plate, it willemploy a PV element of triple-junctionamorphous silicon alloy solar cellsmade with United Solar's proprietaryUNI-SOLAR technology, in which thematerial and thermal characteristics are well suited for combined PV/Tapplications.

Ballast-Mounted PV Arrays. AscensionTechnology will develop analytic andexperimental capabilities for quantify-ing the balance between driving (wind,seismic) forces and the restraining(gravitational/frictional) forces that

must exist for the ballast-mountingapproach to succeed. AscensionTechnology has already developed aballast-mounting system for PV arrays.The system is applicable for both newand retrofit construction on flat ornearly flat roofs, typically on commer-cial buildings.

PV String Inverters. Advanced EnergySystems, Inc., proposes to design andmanufacture a low-cost string invertersystem (SIS), which will minimize thecost of the BOS components (i.e., theinverter and the PV output circuitwiring). The SIS is an inverter and associated wiring that is designed tooperate with a single string of photo-voltaic (PV) modules. By using a singlestring, the need for an expensive string-combiner is eliminated. The parallelingof multiple strings is accomplished bythe utility or AC side of the system,which can result in inexpensive instal-lation costs.

Field-Applied PV Membrane. UnitedSolar Systems Corp., in collaborationwith Energy Conversion Devices, Inc.,the National Association of HomeBuilders, Phasor Energy, Arizona PublicService, Southern California EdisonCo., Southern Cal Roofing, ATASInternational, Elk Corp., and San DiegoGas & Electric intend to develop a field-applied, flexible photovoltaic (PV) membrane product for the 'built-environment." UNI-SOLAR PV RollMembrane is aflexible PV lami-nate designed for arange of marketapplications, suchas covered parkingstructures, "flat"roof commercialbuildings, archi-tectural and struc-tural metal roofing(including newconstruction andretrofit, flat, andcurved roofs),facades, prefabri-cated stress skinpanel production,

and fabric roofing systems. The UNI-SOLAR PV Membrane will beshipped directly to the site for fieldapplication or to a building productcompany for integration with its ownproducts. The membrane uses UnitedSolar Systems Corp.�s multijunction a-Si stainless steel PV cells laminated in flexible UL-approved materials.

PowerRoofTM 2000. PowerLightCorporation, in cooperation withAstroPower, Solarex, BP Solar, andSiemens Solar, proposes to develop aninnovative building-integrated PV roofing system called PowerRoofTM

(Figure 6). PowerGuard® is the firstcore product in the PowerRoof familyand has been successfully developedunder prior programs. The PowerRoof2000 proposal targets the developmentof two next-generation core PowerRoof building products, HeatGuardTM andPowerThermTM. Each builds upon theproven technological approach of thePowerGuard solar electric roofing system.

Other PV for Buildings Products onthe Market and on the Horizon.Building designers have shown greatinterest in the new PV-for-buildingssystems, as indicated by the number ofparticipants in BIPV workshops forarchitects sponsored by DOE, theAmerican Institute of Architects (AIA),and other organizations. In general,

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building designers want PV systemsthat can be integrated into the buildingenvelope and blend well with otherbuilding envelope components andmaterials. Many of the products thathave been or are being developed withassistance from the PV:BONUSProgram meet these criteria.

New products such as transparent thin-film PV modules, for which thedesigner can specify the transmissivity,are expected to become commerciallyavailable in the near future. Thedesigner will be able to specify bothview glass and curtain wall PV modules, so that the entire facade of a building can be clad in PV. Manu-facturers predict that the price of these

PV modules will be close to that ofhigh-end glass products, making it easier for designers to justify the cost of PV.

Designers are beginning to integratephotovoltaics into sunshade buildingcomponents. Sunshades are used toreduce the direct solar gain into a build-ing, which also reduces the buildingcooling loads (Figure 5). The angle ofthe sunshade can also be set to optimizethe output of the PV/sunshade system.

Several PV-roofing products are now commercially available. One crystalline-silicon-cell product replacestraditional roofing materials and is usually used in new construction.

Other products are designed to be usedin flat-roof commercial retrofit applica-tions. They include an insulated unitwith PV integrated into the top layerand a roof membrane product with PVintegrated into the membrane.

The cutting-edge PV products dis-cussed in this paper are only an exam-ple of what is available or expected tobecome available for buildings applica-tions. This is not an exhaustive list,however.

Source: Sheila J. Hayter, P.E., andRobert L. Martin, "Photovoltaics forBuildings, Cutting Edge PV," presentedat the Utility PV Experience Conference& Exhibition, October 1998.

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BIPV Terminology 69

BIPV TerminologyBuilding-integrated photovoltaics (BIPV) is a relatively recent new application ofphotovoltaic (PV) energy technologies. These are some of the basic terms used indescribing PV technologies, BIPV products, and their uses:

Antireflection coating � a thin coating of a material that reduces light reflectionand increases light transmission; it is applied to the surface of a photovoltaic cell.

Balance of System (BOS) � Non-PV components of a BIPV system typicallyinclude wiring, switches, power conditioning units, meters, and battery storageequipment (if required).

Bypass diode � a diode connected across one or more solar cells in a photovoltaicmodule to protect these cells from thermal destruction in case of total or partialshading of individual cells while other cells are exposed to full light.

Conversion efficiency � Amount of electricity a PV device produces in relation to the amount of light shining on the device, expressed as a percentage.

Curtain wall � an exterior wall that provides no structural support.

Encapsulant � Plastic or other material around PV cells that protects them fromenvironmental damage.

Grid-connected � Intertied with an electric power utility.

Inverter � Device that transforms direct-current (DC) electricity to alternating-current (AC) electricity.

Module � Commercial PV product containing interconnected solar cells; modules come in various standard sizes and can also be custom-made by the manufacturer.

PV array � Group or string of connected PV modules operating as a single unit.

PV laminate � Building component constructed of multilayers of glass, metal orplastic and a photovoltaic material.

PV solar cell � Device made of semiconductor materials that converts direct or diffuse light into electricity; typical PV technologies are made from crystalline,polycrystalline, and amorphous silicon and other thin-film materials.

Solar access � Insolation incidence of solar radiation that occurs on a PV system�s surface at any given time; it determines the potential electrical output of a BIPV system.

Stand-alone � Remote power source separate from an electric utility grid; astand-alone system typically has a battery storage component.

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Kiss, G.; Kinkead, J.; Raman, M. (1995).Building-Integrated Photovoltaics: A CaseStudy. NREL/TP-472-7574. Golden,CO: National Renewable EnergyLaboratory.

Maycock, P.D. (1994). "InternationalPhotovoltaic Markets, Developmentsand Trends: Forecast to 2010." RenewableEnergy,Vol. 5, Part I; pp. 154�161.

Murphy, A. (1998) Pacific NorthwestNational Laboratory. Personal commu-nication. See also http://www.energy-codes.org/meccheck/

National Renewable EnergyLaboratory. (1997). Solar ElectricBuildings: An Overview of Today’sApplications (Revised). DOE/GO-10097-357. Produced for the U.S. Departmentof Energy. Golden, CO: NREL.

National Renewable EnergyLaboratory. (1994). Solar Radiation DataManual for Flat-Plate and ConcentratingCollectors. NREL/TP-463-5607,DE93018229. Golden, CO: NREL, April.

Paradis, A.; Shugar, D.S. (1994)."Photovoltaic Building Materials." SolarToday, Vol. 8, No. 3, May/June; pp.34�37.

Polansky, M.; Gnos, S. (1993)."Introduction to a New FactoryBuilding with Photovoltaic Facades andPhotovoltaic Skylights That Cover 70%of the Total Energy Requirements."Proceedings of the Third EuropeanConference on Architecture, 17�21 May,Florence, Italy; pp. 254�256.

Schoen, T.J.N. (1994). "An Introductionto Photovoltaics in Buildings."Proceedings of the Third InternationalWorkshop on Photovoltaics in Buildings,September, Cambridge, Massachusetts,Section 1; pp. 1�9.

Schoen, T.; Prasad, D.; Toggweiler, P.;Eiffert, P.; and Sorensen, H. (1997).�Building with Photovoltaics�TheChallenge for Task VII of the IEA PVPower Systems Program.� Proceedings ofthe EC Photovoltaic Energy Conference,Vienna.

Shugar, D.S. (1990). "Photovoltaics inthe Utility Distribution System: TheEvaluation of System and DistributionBenefits." Proceedings from the Institute of Electrical and Electronics Engineers: The Conference Record of the Twenty-FirstPhotovoltaic Specialists Conference, Vol. II;pp. 836�843.

Sick, F.; Erge, T. (eds). (1996).Photovoltaics in Buildings. IEA Task 16.London: James & James.

Taylor, P.; Becker, M.; Ezell, L. (1997)."Technical Assistance for New FederalBuildings Case Study: SmithsonianInstitution Air and Space MuseumDulles Center." Energy & EnvironmentalVisions for the New Millennium.Proceedings of the 20th World EnergyEngineering Congress, Nov. 19�21.

U.S. Department of Energy. (1998).Federal Technology Alert: Photovoltaics.DOE/GO-10098-484. Washington, DC:US DOE, April.

U.S. Department of Energy. (1995).Tapping Into the Sun. DOE/CH10093-203-Rev1, DE93000075. Washington,DC: US DOE, April.

Walker, H., et al. (1997). "BuildingIntegrated Photovoltaic System: TheThoreau Center for Sustainability."Proceedings of the American Solar EnergyAnnual Conference, April 25�30,Washington, DC.

Wenger, H.; Eiffert, P. (1996). "TheArchitect�s Perspective on the Use ofPV in Buildings: QuestionnaireResults." Building Energy Proceedings, 1st Solar Electric Building Conference,March 4�6, Boston, Massachusetts.

70 Bibliography

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Appendix A:International Activities

"Building with Photovoltaics — The Challenge For Task VII Of The IEA PV Power SystemsProgram" by T. Schoen1, D. Prasad2, P. Toggweiler3, P. Eiffert4 and H. Sørensen5

1: Ecofys Energy and Environment, P.O. Box 8408, NL-3503 RK Utrecht,

2: National Solar Architecture Research Unit, UNSW, Sydney NSW 2052, Australia,

3: ENECOLO, Lindhofstrasse 13, CH-8617 Mönchaltorf, Switzerland

4: National Renewable Energy Laboratory, Center for Energy Analysis and Application, 1617 Cole Blvd, Golden, CO 80401, USA,

5: Esbensen Consulting Engineers, Teknikerbyen 38, DK-2830 Virum, Denmark

AbstractOn January 1, 1997, a new Task started within International Energy Agency�s PhotovoltaicPower Systems (IEA PVPS) Program: Task VII. The objective of Task VII is to enhance the archi-tectural quality, the technical quality and the economic viability of PV systems in the built envi-ronment and to assess and remove non-technical barriers to their introduction as anenergy-significant option. The value of building integration for the introduction of grid-con-nected PV is recognized around the world. Rooftop programs, aiming at large-scale applicationin the next century, are carried out in many countries. In order to reach this widespread applica-tion, however, cost reductions still are essential. BIPV research and development should there-fore focus on achieving these cost reductions, by optimizing integration concepts, bydeveloping new building products and by the development of standardized products.

Building-integrated PV does more than offer perspectives for the next century. PV systems areinstalled today by building owners who appreciate the added value of solar roofs and facades,and who are willing to pay a premium for PV. This market potential must be captured andassisted. From the research and development side, this can be done by focusing on architecturalissues and on non-technical barriers that impede short-term market penetration. The work inTask VII concentrates on all these aspects. The Task VII research and development strategy is toenhance systems technologies, to work on the architecture of building integrated PV, and toassess and remove non-technical barriers that impede the widespread application of PV in thebuilt environment.

Note: One ECU is approximately equivalent to one U.S. dollar.

Appendix A: International Activities 71

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INTRODUCTIONIt is generally expected that in the nextcentury, photovoltaics will be able tocontribute substantially to the main-stream power production, even thoughPV now is up to five times more expen-sive than grid power.

In densely populated areas, such asmajor parts of Europe, Japan and theUS, large-scale realization of systemswill only be possible through distrib-uted PV systems in the urban environ-ment since no land is available for theinstallation of ground-based systems.Rooftop programs in Japan (70,000+),US (1,000,000) and Europe (1,000,000)illustrate the worldwide attention givento building-integrated PV.

Integration of PV into buildings offerscost advantages that make this conceptattractive for urbanized regions as wellas for less densely populated areas withsufficient unoccupied land available.PV installations can be installed on surfaces of buildings and along roadsor railways, with the possibility to combine energy production with otherfunctions of the building or non-building structure. Compared withlarge-scale, ground-based PV powerplants, cost savings through these com-bined functions can be substantial, e.g.,in expensive facade systems wherecladding costs may equal the costs ofthe PV modules.

Additionally, no high-value land isrequired, and no separate supportstructure is necessary. Electricity is gen-erated at the point of use. This avoidstransmission and distribution lossesand reduces the utility company's capital and maintenance costs.

Following the advantages of buildingintegration, more and more countriesview distributed PV as a power sourcewith a large potential for the future andare correspondingly starting to con-struct and operate building-integratedPV systems on a large scale [1].

THE COSTS OF BIPVFigure 1 gives the breakdown of theaverage costs for building-integratedPV systems, though estimates varyfrom country to country.

As can be seen in this figure, the costsfor building integration currently rangefrom 30% to 50% of the total systemcosts. Reduction of module costs willenlarge the need for attention to opti-mal building integration, i.e., reducingthe costs for substructures, mountingand wiring to the absolute minimum.

In order to achieve widespread applica-tion of PV as a competitive powersource, PV electricity must be producedat the level of 0.05 to 0.10 ECU per kWh(5¢ to 10¢). From Fig. 1, it can be seenthat even for Italy, this would requirecost reductions by a factor 3 to 4. In theNetherlands, cost reductions by a factor10 or more are required.

Here is where the major challenge lies for R&D programs in the field ofBIPV: cost reductions are essential forlarge-scale introduction of building-integrated PV systems. R&D shouldfocus on these cost reductions.

PV FOR THE FUTURE — PV FOR TODAYIn addition to cost reduction opportuni-ties as previously mentioned (such asreplacement of building materials andavoidance of land use), building inte-gration offers interesting cost benefits.If PV systems are installed as decentral-ized power systems on buildings, and if net metering is used for selling backsurplus power to utilities, PV electricitywill only have to be produced at con-sumer tariff prices, ranging from 0.10 to0.20 ECU per kWh. For the Netherlandsthis implies required cost reductions by a factor of 3 to 5. For Italy, costreductions by a factor of 2 to 3, or in the optimistic scenario, a 50% costreduction would be sufficient for market introduction.

Given the cost reductions that havebeen achieved by BIPV R&D programs

in the last five years, it can be estimatedthat these cost reductions will bereached within only a few years, indi-cating that BIPV will rapidly becomeinteresting and competitive.

PV, well integrated into the architec-tural design of the building, canenhance the aesthetics of the buildingand give the property owner a 'green'and self-sufficient image. Owners ofcommercial buildings are increasinglymore interested in installing PV sys-tems as a high-value feature of theirproperty. Projects are being realizedwith limited or no government supportat all, indicating that cost reductions ofa mere 25% to 50% are sufficient foropening up the market.

The housing market is increasingly sen-sitive for this 'added value' of the PVsystem; house owners are willing topay a premium price for a PV-cladhouse, thereby generating additionalfunding for the PV system.

The AC module system seems to bevery attractive for this type of applica-tion. Property developers in theNetherlands have shown interest inintroducing PV systems consisting of4 AC modules on a regular basis in thebuilding programs, if the prices arereduced to 5 ECU ($5) per Wp. Thismakes PV a technology not just for thefuture but also for today.

The challenge of national programs aswell as international actions, such asTask VII, is to assist these emergingmarkets by developing photovoltaicsinto a cost-effective and clean powersource, available for application in dis-tributed systems of utilities, builders,and cities of the future as well as today.R&D should therefore not only addresslong-term developments for large-scaleapplication as a bulk power source, butalso short-term application as competi-tive feature of the built environment.The integration of PV into architectureand the building market are importantissues in such an R&D strategy.

72 Appendix A: International Activities

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Upscaling of the near-term BIPV mar-ket will, moreover, be possible only ifnon-technical barriers that impede theapplication of BIPV are addressed anddealt with successfully. The major bar-rier to overcome here could well be theinvolvement of builders and buildingowners in the design and implementa-tion of building integrated PV. R&D, as well as pilot and demonstration projects, should work on the achieve-ment of this involvement as well as on the removal of other non-technicalbarriers such as the lack of information,confidence, or appropriate financingmechanisms.

R&D STRATEGIES FORTASK VIIIn recognition of the potential of building-integrated PV to the develop-ment and introduction of photovoltaics,IEA's PV Power Systems Program inJanuary 1997 launched a new task: TaskVII - PV in the Built Environment.

The objective of Task VII is to enhancethe architectural quality, the technicalquality, and the economic viability ofPV systems in the built environmentand to assess and remove non-technicalbarriers to its introduction as an

energy-significant option. This objec-tive reflects the R&D strategies men-tioned earlier.

The primary focus of Task VII is on the integration of PV into the architecturaldesign of (roofs and facades of residen-tial, commercial, and industrial) build-ings and other structures in the builtenvironment (such as noise barriers,parking areas, and railway canopies).Also important are the market factors,both technical and non-technical, thatneed to be addressed and resolvedbefore wide adoption of PV in the builtenvironment will occur.

Essential for the success of Task VII isthe active involvement of urban plan-ners, architects, building engineers, and the building industry. Task VII isvery keen on the collaboration betweenthese groups and PV system specialists, utility specialists, the PV industry, and other professionals involved inphotovoltaics.

The joint effort will consist mainly ofthe evaluation and development ofinnovative concepts for the integrationof PV into the built environment, thedemonstration of integration concepts,contribution to the development of

standards and guidelines, and thestudy of economic aspects and othermarket factors that impede the wide-spread application of PV in buildings.

In brief, Task VII will work on R&D inthe following fields:

(1) BIPV technologies

(2) PV and architecture

(3) Non-technical barriers

BIPV TechnologiesThe technologies that are now availablefor the integration of PV into buildingsare, in general, too expensive for large-scale introduction. Cost reductions are thus still essential. They can beachieved by carefully redesigning thePV support structure, and by integrat-ing the PV system into well-knownbuilding components such as the pre-fabricated roof or the structural-glazingfacade.

Development of standardizedPV/building unitsThe development of low-cost, flat roof-mounting elements such as the Sofrel[3] show that, through careful redesignof substructures from the low-costpoint of view, cost reductions up to 50% are possible for substructure andmounting costs. A similar strategycould be applied in the development ofmounting structures for sloped roofsand facades. PV facades in general stilluse tailor-made solutions, suitable onlyfor custom-made modules, requiringcase-by-case engineering and installa-tion by specialists, which lead to high-quality but high-price solutions.

For new buildings, integration of stan-dard PV modules into low-cost, every-day cladding systems is required,whereas for existing buildings, low-costadd-on systems offer good cost per-spectives. In order to make mountingconcepts suitable for application in thevast number of existing buildings witha poor energy balance, add-on systemsshould include extra thermal insulationlayers.

Appendix A: International Activities 73

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Figure 1. Overview of BIPV system costs in ECU/Wp (left) and the resulting PV electricity costs in ECU/kWh (right), for different countries andcalculation methods (optimistic: maximum performance ratio, low interestrate; pessimistic: average performance ratio, high interest rate). Note: Currently, the ECU is equivalent to one U.S. dollar.

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Integration of PV modules andcells into standard buildingmaterialsThe integration of PV into well-knownbuilding materials, such as roof tiles, is under way. Attention to these devel-opments around the world shows thecost reduction potential of this R&Dpath.

Optimal tuning of PV modules to exist-ing building materials can result in sub-stantial reduction of mounting andsubstructure costs. In the end, thesecosts might be fully omitted throughthe integration of PV cells into buildingmaterials. Similar attempts are beingmade in the field of stand-alone PV sys-tems, where PV cells are being inte-grated into bus shelters, vessels, andother applications.

Integration of PV intoprefabricated building elementsThis R&D path is especially suitable for countries where the prefabricatedbuildings and building components arecommonly used (e.g., the Netherlands,Japan). Preliminary research indicatesthat cost reductions up to 50% (com-pared with that of today's technology)through prefabrication are possible [4].

PV and ArchitectureMarket enhancement requires accep-tance of PV by builders, architects, andusers. Full integration into architectureis therefore essential.

The physical characteristics of PV prod-ucts for integration in buildings mustmeet architectural requirements forcolor, size, and materials. Products that meet theserequirements are being developedaround the world. Cells are available in different colors and textures; mod-ules can be produced to the designer�sspecification.

These developments have certainlyassisted the creation of high-end, high-quality examples of building-integratedPV. They are thus very important to theintroduction of BIPV.

It should, however, be noted that theapplication of custom-made PV prod-ucts has economic consequences. Thecosts of modules can go down substan-tially if they are produced in bulk. At aproduction level of 500 MWp per year,costs of less than 1 ECU ($1) per Wp areachievable with today's technologies[5]. This cost level will not be reachedwith tailor-made modules produced on a smaller scale.

The challenge for the PV R&D com-munity, together with architects andbuilders, is to develop high-qualityintegration concepts that can make use of the low-cost potential of bulk-produced modules.

As a first activity, Task VII has dealtwith the evaluation of existing BIPVprojects. The result is a list of architec-tural quality criteria for BIPV projects(please see Table 1).

Using these criteria in the design ofnew projects and integration conceptsbased on standard modules canenhance the architectural quality ofBIPV without introducing high-cost(custom-made) products.

Non-Technical BarriersAs mentioned above, a number of non-technical barriers exist that impede the implementation of PV in buildings.Assessment and removal of these barri-ers will result in enhancement of boththe near-term and the long-term PVmarket. A preliminary listing of barriershas been prepared byTask VII. Task VII willwork on the analysis ofthese market barriers,followed by recom-mendations for theirremoval.

As can be expected, budgetary constraintsare the main barrier. The removal of otherbarriers, however, will most certainly helpovercome this prime

barrier. A number of R&D actions arediscussed here.

Development of financing schemesThe availability of appropriate financ-ing mechanisms in Germany andSwitzerland has been shown to have amajor impact on the introduction of PV.In Germany, rate-based incentives haveled to a substantial increase in the PVmarket, with annual growth figureslarger than ever (1996: 3 MW;1997:10 MW) [6].

The assessment of such financingschemes, tailored to the specific needsof individual countries, will be one ofthe key activities of Task VII.

Integration into the building processIf PV is to become a well-accepted tech-nology readily available for architects,the building industry, and propertyowners, integration concepts will haveto meet regular building quality stan-dards. This can be achieved by fullyintegrating the PV system into buildingmaterials and by integrating the con-struction process of BIPV systems intothe building construction process.Building integration must include inte-gration into the contractual frameworkand the organizational structure ofbuilding projects.

Building integration also must includeintegration into the regular qualityschemes for building components.

74 Appendix A: International Activities

Table 1: Architectural criteria for the review ofPV buildings and integration products

• Natural integration and visually acceptable

• Architecturally pleasing and visually pleasing

• Good composition between materials and colors

• Fit the grid, harmony, composition

• Appropriately links with the context of the project

• Well-engineered and designed

• Innovative new design

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PV will be largely accepted by builders,architects, and end-users only if thequality of BIPV systems fully meets therequirements of everyday constructionelements.

The development of such qualityschemes is a part of the work of TaskVII as well as an import issue of theEuropean BIPV programs. As an exam-ple, the Joule PRESCRIPT project aimsat the development of guidelines andpre-standards for the testing and certifi-cation of building-integrated PV [7].

Training and educationPV can be included in building projectsonly if architects and principals havesufficient knowledge about PV tech-nologies and appropriate design toolsto assist them.

Design tools can range from planninginstruments to tools for shaping andsizing the PV systems. Planning instru-ments are required to ensure that PV is

taken into account from the very startof the building process, where the firstdecisions have a major impact on theways to include PV in the building (e.g.,the orientation of the building). Toolsfor shaping and sizing of the PV systemcan range from intricate software pack-ages (linked to the overall energydesign tools) to easy aids as an irradia-tion disk.

R&D is required in both energy plan-ning and the design and sizing of PVsystems, within the overall design ofthe energy system of the building.

Concerning education, 'PV at schools'programs have proven to be successfulin a number of European countries [8].In order to teach the architects,builders, and occupants of the futurehow to work with PV, integration of PVinto educational programs at all levelsis important. A follow-up of nationalactivities at the European level couldenhance this process.

FINAL REMARKSThe aforementioned R&D directions arereflected in the projected activities ofTask VII. It can, therefore, be concludedthat Task VII can contribute to the fur-ther development and implementationof PV in the Built Environment. Thesuccess of Task VII will of coursedepend on the effectiveness of the international collaboration and on the contributions of the participatingcountries to the overall framework ofthe Task.

The coming five years will show ifTask VII can achieve its challengingobjective. All experts in the countriesparticipating in Task VII are requestedto closely follow the task and, whereappropriate, collaborate in its work.

REFERENCES[1] Palz, W., and Van Overstraeten, R.

(1995). Strategic Options for PVDevelopment in Europe. In:Proceedings of the 13th ECPhotovoltaic Energy Conference,883–886.

[2] Barnes, H. (ed) (1997). Photovoltaicpower systems in selected IEA member countries. EA Technology,Capehurst Chester, UK.

[3] Toggweiler, P., Ruoss, D., Roecker, C.,Bonvin, J., Muller, A., and Affolter, P.(1997). Sofrel flat roof system and firstinstallation. In: Proceedings of the14th EC Photovoltaic EnergyConference, 701–704.

[4] Boumans, J.H. and Schoen, T. (1996).Prefab Energy-roof — trends anddevelopments. Ecofys, Utrecht, theNetherlands.

[5] Bruton, T.M, e.a. (1997). A study of theManufacture of 500 Wp p.a. ofCrystalline Silicon PhotovoltaicModules. In: Proceedings of the 14thEC Photovoltaic Energy Conference,11–16.

Appendix A: International Activities 75

Figure 2: The National Association of Home Builders 21st CenturyTownhome at the National Research Home Park in Bowie, Maryland, USA;it is one of the Task VII projects to be evaluated.

Tim

Elli

son,

EC

D/P

IX04

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[6] Gabler, H., Heidler, K., and Hoffmann,V.U. (1997). Market Introduction ofGrid-Connected PhotovoltaicInstallations in Germany. In:Proceedings of the 14th ECPhotovoltaic Energy Conference,27–32.

[7] Van Schalkwijk, M., Hoekstra, K.J.,Schoen, T., and Van der Weiden, T.C.J.(1997). Quality Assurance of PVIntegration in Buildings: Experiencesfrom Practice and Future Outlook. In:Proceedings. of the 14th ECPhotovoltaic Energy Conference,1616–1619.

[8] Nordmann, T. (1995). The Swiss 1 MWpPV-School Demonstration Program. In:Proceedings of the 13th ECPhotovoltaic Energy Conference,894–897.

76 Appendix A: International Activities

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AustraliaDeo [email protected]

AustriaReinhard Haas [email protected]

CanadaPer Drewes [email protected]

DenmarkHenrik Sorensen [email protected]

GermanyHermann Laukamp [email protected]

NetherlandsHenk Kaan [email protected]

Bert [email protected]

Tjerk Reijenga [email protected]

Tony Schoen [email protected]

SpainNuria Martin [email protected]

SwedenMats Andersson [email protected]

SwitzerlandChristian Roecker [email protected]

Peter Toggweiler [email protected]

United KingdomDavid Lloyd Jones [email protected]

Donna Munro [email protected]

Paul Ruyssevelt [email protected]

United StatesPatrina [email protected]

Steven [email protected]

Appendix B: Contacts for International Energy Agency Photovoltaic Power System Task VII 77

Appendix B:Contacts for International Energy Agency

Photovoltaic Power System Task VII —Photovoltaics in the Built Environment

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Appendix C:Design Tools

Dru Crawley, DOE Program Manager for Building Energy Tools, has established a BuildingEnergy Software Tools Directory. This directory is available on the Internet online; seehttp://www. eren.doe.gov/buildings/tools_directory/.

Software building design tools are divided into categories that include Energy Simulation,Utility Evaluation, Energy Economics, Atmospheric Pollution, Envelope Systems, Solar ClimateAnalysis, Codes and Standards: Development and Compliance, and Load Calculations. Thesoftware tools described in this section may be particularly useful to those designing buildingsand other structures into which photovoltaic power systems are integrated.

78 Appendix C: Design Tools

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AWNSHADEThis program calculates the unshadedfraction of a rectangular window forany given solar position coordinatesrelative to the window. Calculations aremade for window shading configura-tions, including awnings, with or with-out side walls or overhangs of arbitrarydimensions above the window.Awnshade can also calculate theunshaded fraction for a sequence ofsolar positions. It calculates the effec-tive unshaded fraction of diffuse skyirradiance or illuminance incident onthe window, assuming uniform skyradiance/luminance, and the effectiveground-reflected unshaded fraction. Itcan handle cases in which shadows ofthe side of the awning/overhang crossthe top of the window.

Audience: This is for architects, buildingdesigners, building energy perfor-mance simulators.

Expertise Required: Basic understandingof building shading geometry.

Input: User-friendly I/O screens,describing geometry of windows,awnings, and vertical side fins.

Output: Results can be printed directlyto a printer, saved to a print file, orsaved to files formatted for importinginto graphic plotting programs.

Strengths: Outputs a table of unshadedfractions for a range of incident sundirections.

Weaknesses: No fancy graphics of win-dow shadows or their movement acrossthe window.

Availability: Awnshade version 2.0 isavailable from the contact at a cost of$45 (including shipping and handling).

Contact: Joanne Stirling, Document Sales OfficeFlorida Solar Energy Center1679 Clearlake RoadCocoa, Florida 32922-5703Telephone: 407- 638-1414Facsimile: 407-638-1439E-mail: [email protected]: http://www.fsec.ucf.edu

BEES A powerful technique for selecting cost-effective, environmentally preferablebuilding products, BEES (Building forEnvironmental and Economic Sustain-ability) is based on consensus stan-dards. The Windows-based decisionsupport software, aimed at designers,builders, and product manufacturers,includes actual environmental and eco-nomic performance data for a numberof building products.

BEES measures the environmental per-formance of building products by usingthe environmental life-cycle assessmentapproach specified in the latest versionsof ISO 14000 draft standards. All stagesin the life of a product are analyzed:raw material acquisition, manufacture,transportation, installation, use, recycling, and waste management.Economic performance is measuredusing the American Society for Testingand Materials (ASTM) standard life-cycle cost method, which covers thecosts of initial investment, replacement,operation, maintenance, repair, and disposal. Environmental and economicperformance are combined into anoverall performance measure using theASTM standard for Multi-AttributeDecision Analysis. For the entire BEESanalysis, building products are definedand classified according to the ASTMstandard classification for building elements known as UNIFORMAT II.

Audience: This is for designers, speci-fiers, builders, product manufacturers,researchers, and policy makers.

Expertise Required: None; there weremore than 500 users in the first 6months of availability, both in the U.S.and abroad.

Input: The user sets relative importanceweights for (1) synthesizing six envi-ronmental impact scores (global warm-ing, acid rain, nutrification, resourcedepletion, indoor air quality, solidwaste) into an environmental perfor-mance score; (2) discounting futurecosts to their equivalent present value;and (3) combining environmental andeconomic performance scores into an

overall performance score. Default values are provided for all of thisWindows-based input.

Output: Summary graphs depicting life-cycle environmental and economicperformance scores for competingbuilding product alternatives. Detailedgraphs are also available, depictingscores for the six environmentalimpacts underlying the life-cycle envi-ronmental performance score, anddepicting first and future costs underly-ing the life-cycle economic performancescore. Graphs are live in the sense thatalternative graph types (pie graph, bargraph, etc.) may be displayed; rows andcolumns may be moved; colors, labels,and other display attributes may becustomized; and graphs may beprinted.

Computer Platform: Windows 95 orhigher personal computer with a 486 or higher microprocessor, 32 megabytesor more of RAM, at least 10 megabytesof available disk space, and a 3.5-in.floppy diskette drive. The program-ming language is CA Visual Objects.

Strengths: The program offers a uniqueblend of environmental science, deci-sion science, and economics. It uses life-cycle concepts, is based on consen-sus standards, and is designed to bepractical, flexible, and transparent. It ispractical in its systematic packaging ofdetailed, science-based, quantitativeenvironmental and economic perfor-mance data in a manner that offers useful decision support. It is flexible in allowing tool users to customizejudgments about key study parameters.It is transparent in documenting andproviding all the supporting perfor-mance data and computational algorithms.

Weaknesses: It includes environmentaland economic performance data foronly 24 building products covering 12 building elements.

Availability: BEES 1.0 software andprinted documentation available free of charge through the EPA PollutionPrevention Information Clearinghouseat 202-260-1023 or via e-mail,

Appendix C: Design Tools 79

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[email protected]. BEES wasdeveloped by the NIST Green BuildingsProgram with support from the EPAEnvironmentally Preferable PurchasingProgram.

Contact:Barbara C. Lippiatt National Institute of Standards and Technology

Office of Applied Economics 100 Bureau Drive, Stop 8603Gaithersburg, Maryland 20899-8603Telephone: 301-975-6133 Facsimile: 301-975-5337E-mail: [email protected] Web: http://www.bfrl.nist.gov/oae/ bees.html

BLASTThis program performs hourly simula-tions of buildings, air handling sys-tems, and central plant equipment inorder to provide mechanical, architec-tural, and energy engineers with accu-rate estimates of a building's energyneeds. The zone models of BLAST(Building Loads Analysis and SystemThermodynamics), which are based onthe fundamental heat balance method,are the industry standard for heatingand cooling load calculations. BLASToutput may be utilized in conjunctionwith the LCCID (Life Cycle Cost inDesign) program to perform an eco-nomic analysis of the building, system,and plant design.

Audience: Mechanical, energy, andarchitectural engineers working forarchitectural-engineering firms, con-sulting firms, utilities, Federal agencies,research universities, and research labo-ratories.

Expertise Required: High level of com-puter literacy not required; engineeringbackground helpful for analysis of air-handling systems.

Input: Building geometry, thermal char-acteristics, internal loads and sched-ules, heating and cooling equipmentand system characteristics. Readable,structured input file may be generatedby HBLC (Windows) or the BTEXT program.

Output: More than 50 user-selected, formatted reports printed directly byBLAST; the REPORT WRITER programcan generate tables or spreadsheet-ready files for more than 100 BLASTvariables.

Strengths: PC Format has Windowsinterface as well as structured textinterface; detailed heat balance algo-rithms allow for analysis of thermalcomfort, passive solar structures, highand low intensity radiant heat, mois-ture, and variable heat transfer coeffi-cients æ none of which can be analyzedin programs with less rigorous zonemodels.

Weaknesses: High level of expertiserequired to develop custom system andplant models.

Availability: Software prices range from$450 for an upgrade package to $1500for new installations. This package contains complete sources, almost 400weather files, numerous documentsabout using BLAST as well as docu-mentation (all on CD ROM). Contactthe Building Systems Laboratory foradditional information.

Contact: Building Systems LaboratoryUniversity of Illinois1206 West Green StreetUrbana, Illinois 61801Telephone: 217-333-3977Facsimile: 217-244-6534E-mail [email protected]: http://www.bso.uiuc.edu

BUILDING DESIGN ADVISORThis provides a software environmentthat supports the integration of multi-ple building models and databasesused by analysis and visualizationtools, through a single, object-basedrepresentation of building componentsand systems. Building Design Advisor(BDA) acts as a data manager andprocess controller, allowing buildingdesigners to benefit from the capabili-ties of multiple analysis and visualiza-tion tools throughout the buildingdesign process. BDA is implemented asa Windows-based application. The 1.0

version has links to a SchematicGraphic Editor and two simplified simulation tools, one for daylight andone for energy analyses.

Audience: Architects and engineersworking in early building designphases.

Expertise Required: Knowledge ofWindows applications; there are at least200 users.

Input: Graphic entry of basic buildinggeometry and space arrangements.Default descriptive and operationalcharacteristics can be edited by user.

Output: User-selected output parame-ters displayed in graphic form, includ-ing 2-D and 3-D distributions.

Computer Platform: PC-compatible,Windows 95/98/NT, 30 megabytes ofhard disk space; the programming language is C++.

Strengths: It allows comparisons of mul-tiple design solutions with respect tomultiple descriptive and performanceparameters. It also allows the use ofsophisticated analysis tools from theearly, schematic phases of buildingdesign, and does not require the user tohave in-depth knowledge to use linkedtools for energy, daylighting, and otheranalyses.

Weaknesses: Version 1.0 is linked to simplified tools for daylight and energy analyses.

Availability: Version 1.0 is available atthe Web site below.

Contact:Konstantinos Papamichael Lawrence Berkeley National Laboratory

Mail Stop 90-3111 1 Cyclotron Road Berkeley, California 94720Telephone: 510-486-6854 Facsimile: 510-486-4089E-mail: [email protected] Web: http://kmp.lbl.gov/BDA

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CLIMATE CONSULTANTThis program graphically displays cli-mate data in dozens of categories usefulto architects. These include tempera-tures, wind velocity, sky cover, percentsunshine, psychrometric chart,timetable of bioclimatic needs, suncharts, and sun dials showing hourswhen solar heating is needed and whenshading is required. The psychrometricanalysis recommends the most appro-priate passive design strategy as out-lined in Givoni, Man, Climate andArchitecture (ref. date). It also developsthe kind of data incorporated in Watsonand Labs, Climatic Design (ref. date).

Audience: Architects, students of architecture.

Expertise Required: Intended to be self-instructional, the program requiresonly basic familiarity with computersand architectural vocabulary.

Input: Typical Meteorological Year(TMY) weather data in short format.

Output: Graphic plots of weather data.

Strengths: Highly graphic, user-friendly.

Weaknesses: Requires weather data inTMY weather data format.

Availability: Not copy protected; sharingis encouraged. It is most easily aquiredby copying a disk or by downloadingoff the Web; otherwise, users can send acheck to the technical contact for $35,payable to the Regents of theUniversity of California.

Contact: Professor Murray MilneDepartment of Architecture and Urban Design

Box 951467University of California at Los AngelesLos Angeles, California 90095-1467USATelephone: 310-825-7370Facsimile: 310-825-8959E-mail: [email protected]: http://www.aud.ucla.edu/ energy-design-tools

DOE-2 This is an hourly, whole-buildingenergy analysis program calculatingenergy performance and life-cycle costof operation. It can be used to analyzethe energy efficiency of given designsor the efficiency of new technologies.Other uses include utility demand-sidemanagement and rebate programs,development and implementation ofenergy efficiency standards and com-pliance certification, and training a newcorps of energy-efficiency-consciousbuilding professionals in architectureand engineering schools.

Audience: Architects, engineers in pri-vate A&E firms, energy consultants,building technology researchers, utilitycompanies, state and Federal agencies,and university schools of architectureand engineering.

Expertise Required: A high level of com-puter literacy is required; a 5-day ses-sion of formal training in basic andadvanced DOE-2 use is recommended.There are 800 user organizations in the United States and 200 user organi-zations internationally; user organiza-tions consist of 1 to 20 or moreindividuals.

Input: Hourly weather file plusBuilding Description Language inputdescribing geographic location andbuilding orientation, building materialsand envelope components (walls, win-dows, shading surfaces, etc.), operatingschedules, HVAC equipment and con-trols, utility rate schedule, buildingcomponent costs. The program is avail-able with a range of user interfaces,from text-based to interactive/graphi-cal windows-based environments.

Output: Twenty user-selectable inputverification reports, 50 user-selectablemonthly/annual summary reports, anduser-configurable hourly reports of 700different building energy variables.

Computer Platform: PC-compatible; Sun;DEC-VAX; DECstation; IBM RS 6000;NeXT; 4 megabytes of RAM; mathcoprocessor; compatible with UNIX,

DOS, VMS; the programming languageis FORTRAN.

Strengths: Detailed, hourly, whole-building energy analysis of multiplezones in buildings of complex design; itis widely recognized as the industrystandard.

Weaknesses: A high level of user knowl-edge and computer literacy is required.

Availability: The cost is $300 to $2000,depending upon the hardware platformand software vendor.

Contact:Fred Winkelmann Lawrence Berkeley National Laboratory

Mail Stop 90-3147 1 Cyclotron Road Berkeley, California 94720Telephone: 510-486-5711 Facsimile: 510-486-4089E-mail: [email protected] Web: http://gundog.lbl.gov

EMISSThis software generates a file of localair-pollution emission coefficients. It is used with the BLCC life-cycle costprogram to estimate reductions in emis-sions associated with energy conserva-tion projects. Three types of emissionfactors are currently included: carbondioxide, sulfur dioxide, and nitrousoxide. Emissions factors are specifiedseparately for six different end-useenergy types: electricity, distillate andresidual fuel oil, natural gas, liquidpetroleum gas, and coal. It is distrib-uted in connection with the BLCC life-cycle cost program to several thou-sand users.

Audience: Federal energy managers and energy coordinators; engineers and architects; budget analysts andplanners.

Expertise Required: None required.

Input: Regional or local emissions fac-tors or fuel-specific end-use data.

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Output: Preformatted tables of com-puted emission factors by type of fuel.

Strengths: Emission factors for fossilfuels can be regionalized or localized.Program contains state-specific electric-ity emission factors and U.S. averagesulfur content of fossil fuels as defaultdata. A users guide is included as filewith program.

Weaknesses: The quality of the emissionsfactors depends on the user's knowl-edge of the factors that contribute tothese emissions.

Availability: Free to Federal agenciesthrough the Energy Efficiency andRenewable Energy Clearinghouse, 1-800-DOE-EREC (363-3732).

Contact: Linde FullerNational Institute of Standards and Technology

Office of Applied EconomicsBuilding 226, Rm B226Gaithersburg, Maryland 20899Telephone: 301-975-6134Facsimile: 301-208-6936E-mail: [email protected]: http://www.eren.doe.gov/ femp/

ENERGY-10This is a design tool for smaller residen-tial or commercial buildings (e.g., thosethat are less than 10,000 square feet infloor area) or buildings that can betreated as one- or two-zone increments.The software performs a whole-build-ing energy analysis for 8760 hours per year, including dynamic thermaland daylighting calculations. It isspecifically designed to facilitate theevaluation of energy-efficient buildingfeatures in the very early stages of thedesign process.

Audience: This is for building designers,especially architects; HVAC engineers;utility companies; university schools of architecture and architectural engineering.

Expertise Required: A moderate level ofcomputer literacy is required; two daysof training are advised.

Input: Only four inputs are required togenerate two initial generic buildingdescriptions. Virtually everything isdefaulted but modifiable. User adjustsdescriptions as the design evolves,using fill-in menus, including utility-rate schedules, construction details,materials.

Output: Summary table and 20 graphi-cal outputs are available, generallycomparing current design with basecase. Detailed tabular results are alsoavailable.

Strengths: Fast, easy-to-use, accurate.Automatic generation of base cases and energy-efficient alternate buildingdescriptions; automatic application ofenergy-efficient features and rank-ordering of results; integration of day-lighting thermal effects with thermalsimulation; menu display and modifi-cation of all building-description andother data.

Weaknesses: Limited to smaller build-ings and HVAC systems that are mostoften used in smaller buildings.

Contact:Passive Solar Industries CouncilSuite 6001511 K Street, NWWashington, DC 20005Telephone: 202-628-7400Facsimile: 202-393-5043Online: http://www.psic.org/ energy10.htm

FRESAThis is a first-order screening tool toidentify potentially cost-effective appli-cations of renewable energy technologyon a building and facility level. FRESA(Federal Renewable Energy ScreeningAssistant) is useful for determiningwhich renewable energy applicationsrequire further investigation. Tech-nologies represented include activesolar heating, active solar cooling, solar

hot water, daylighting with windows,daylighting with skylights, photo-voltaics, solar thermal electric (para-bolic dish, parabolic trough, centralpower tower), wind electricity, smallhydropower, biomass electricity (wood,waste, etc.), and cooling load avoidance(multiple glazing, window shading,increased wall insulation, infiltrationcontrol). Life-cycle cost calculationscomply with 10 CFR 436.

Audience: Building energy auditors.

Expertise Required: Must be able togather summary information on build-ing and installation energy use pat-terns; intended for use by trainedauditors; results should be interpretedby someone familiar with the limita-tions of the program.

Input: Summary energy load data; solarand wind resource data provided in adatabase indexed by ZIP code; biomassand solid waste resource data must begathered by the auditor.

Output: Annual cost and energy sav-ings; life cycle economics; a red flag ifan option is viable; viable optionsranked by savings-to-investment ratio.

Strengths: Establishes consistentmethodology and reporting format fora large number of audits in varyinglocations and with varying building use types; sophisticated analyses oftechnology performance and cost while keeping data requirements to aminimum.

Weaknesses: Provides only first-orderscreening, to focus design; requiresmore detailed feasibility analyses onapplications most likely to be cost-effec-tive; requires high level of knowledgeabout energy audits and the limitationsof the program; not suitable for generaluse.

Availability: Available from the technicalcontact.

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Contact: Andy Walker, Ph.D.National Renewable Energy Laboratory1617 Cole BoulevardGolden, Colorado 80401Telephone: 303-384-7531Facsimile: 303-384-7411E-mail: [email protected]: http://www.eren.doe.gov/ femp/techassist/softwaretools/softwaretools.html

IDEALThis software is designed to read elec-tronic data records of facilities� electri-cal energy use; the data records arecompiled by electric utility companiesand normally used internally only forbilling purposes. Upon request, the utility will release the data to the cus-tomer for analysis purposes. These data records are formatted in more than25 distinct file types identified thus far.IDEAL (Interval Data Evaluation andAnalysis of Load) translates all theseformats into a common database andproduces informative graphs andreports to assist the user, the energymanagement team, or consultants inquickly identifying periods of seriouspower mismanagement. Extensions tothe basic program will perform powerbill calculations, time-of-use analysis,temperature and humidity plots, andoptimum standby generator sizing andrun times.

Audience: Industrial and large com-mercial accounts who have electronicmetering on their electrical power ser-vice (typically, loads with more than500 kilowatts demand, and virtually allwith time-of-use metering).

Expertise Required: No special expertiserequired.

Input: Data file, normally obtained fromthe electric utility company, whichincludes interval recordings of powerusage. Program requires data to be anASCII-formatted data file on diskette.

Output: Both detailed and summaryreports of facility electrical usage. Morethan 70 preformatted graphs visually

depict power usage by day, week, ormonth. Variables include kilowatts at a minimum and may include kilovarsand kilovolt-amperes, if the source datafile contains this information.

Strengths: Identifies, by time of day,periods of excessive power demandand consumption. Also useful in bench-marking a facility's power usage beforeenergy measures are implemented andtracking the results after implementa-tion. Ability to immediately utilizemore than 25 data formats withoutprior conversion of the data by the user.

Weaknesses: Limits analysis to month-by-month studies. Can produce recordssuitable for greater-than-one-monthanalysis using conventional spread-sheets. Must use DOS sequences forprinting reports and graphs.

Availability: Download demos from the Web to determine suitability to task.Price negotiable based on number ofcopies; list price $1,000.

Contact: John D. HelmsPC Application Systems4310 Twin Pines DriveKnoxville, Tennessee 37921-5143Telephone: 423-588-7363Facsimile: 423-584-1350E-mail: [email protected]: http://ourworld.compuserve.com/homepages/john_helms/

PV-DesignProThis program simulates photovoltaicsystem operation on an hourly basis forone year, based on a user-selected cli-mate and system design. PV-DesignProis recommended for designs thatinclude battery storage, which can beeither stand-alone systems with genera-tor backup or utility-interconnectedsystems. The purpose of the program is to aid in photovoltaic system designby providing accurate, in-depth infor-mation on the likely system power output and load consumption, backuppower needed during system opera-tion, and the financial impacts ofinstalling the proposed system. The

program CD-ROM includes a climatedatabase of 239 locations in the conti-nental United States, Alaska, Hawaii,Puerto Rico, and Guam and a World-wide Hourly Climate GeneratorProgram that generates hourly climatesfor 2,132 global locations from monthlydata. The SolarPro 2.0 solar water heat-ing program is also included. Six typesof panel surface tracking are incorpo-rated into the program: fixed slope andaxis, tracking on a horizontal east-westaxis, tracking on a horizontal north-south axis, tracking on a vertical axiswith a fixed slope, tracking on a north-south axis parallel to the Earth's axis,and continuous tracking on two axes.Panel shading information can also beinput.

Audience: This program is for PV sys-tem design professionals, architects,engineers, energy offices, universities,and students.

Expertise Required: Knowledge of elec-trical design, PV basics.

Input: Windows 95-based interface;uses the electrical system load by hourfor weekdays, weekends, and holidays;requires panel type from database,number of parallel connections andseries strings of similar panels; batterybackup charging parameters; ACinverter requirements; and climate file.

Output: Solar Fraction charts by month,battery states of charge by month (max-imum, average, minimum), annual performance table (energy produced,necessary backup, and states-of-charge), prospective cash-flows of pur-chased and sold energy, system costs,costs of backup energy, prices of soldenergy, maintenance and replacementcosts, and the estimated life of the sys-tem. A rate of return is calculated, aswell as an overall price per kWh of thesystem and payback years.

Strengths: Most information needed forPV designs is included in databases.

Weaknesses: Resistive loads, such aswater pumping with a motor only, cannot currently be modeled.

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Relatively high level of PV expertiserecommended.

Availability: CD-ROM, $149.00 + $10.00shipping and handling. Price includesWorldwide Hourly Climate Generator1.0 program and SolarPro 2.0 solarwater heating program. See Web site or call for more information.

Contact: Mike PelosiPV-DesignPro SoftwareP.O.Box 1043Kihei, Maui, Hawaii 96753Telephone: 808-879-7880Facsimile:E-mail: [email protected]: http://www.maui.net/ ~sandy/PV-DesignPro.html

Quick BLCCThis program is used to set up multipleproject alternatives for life-cycle costinganalysis in a single input file. The QuickBLCC (Quick Building Life-Cycle Cost)program provides a convenient methodfor solving relatively simple LCC prob-lems that require finding the lowestLCC design alternative among manymutually exclusive alternatives for thesame project. Input data files are trans-ferrable to BLCC for more detailedanalysis.

Audience: Federal energy managers and energy coordinators; engineers and architects; budget analysts andplanners.

Expertise Required: Familiarity with present-value concept is helpful.

Input: Initial investment costs; base-year annual energy costs; maintenance,repair, and replacement costs; timeperiod.

Output: Preformatted tables of inputdata summary and LCC and compara-tive analyses results. Exportable datafiles.

Strengths: Ideal for preliminary eco-nomic evaluation of multiple designalternatives. Users guide is included asfile with program.

Weaknesses: No private-sector tax analy-sis included.

Availability: Free to Federal agenciesthrough the Energy Efficiency andRenewable Energy Clearinghouse, 1-800-DOE-EREC (363-3732).

Contact: Linde FullerNational Institute of Standards and Technology

Office of Applied EconomicsBuilding 226, Rm B226Gaithersburg, Maryland 20899Telephone: 301-975-6134Facsimile: 301-208-6936E-mail: [email protected]: http://www.eren.doe.gov/ femp/techassist/softwaretools/softwaretools.html

SOLAR-2This software plots sunlight penetrat-ing through a window with any combination of rectangular fins andoverhangs. It also plots an hour-by-hour, three-dimensional suns-eye view"movie" of the building. It prints annualtables of the percentage of the windowin full sun, radiation on glass, and otherdata.

Audience: This is for architects, studentsof architecture, building managers, andknowledgeable homeowners.

Expertise Required: Intended to be self-instructional, it requires only basicfamiliarity with computers and archi-tectural vocabulary.

Input: Window, overhangs, and finsgeometry.

Output: Graphic plots, tables.

Strengths: User-friendly, highly graphic.

Weaknesses: Allows only rectangularshading elements.

Availability: Not copy protected; sharingis encouraged. The software is mosteasily aquired by copying a disk or bydownloading off the Web; otherwise,users can send a check to the technical

contact for $35, payable to the Regentsof the University of California.

Contact: Professor Murray MilneDepartment of Architecture and Urban Design

Box 951467University of California at Los AngelesLos Angeles, California 90095-1467Telephone: 310-825-7370Facsimile 310-825-8959E-mail: [email protected]: http://www.aud.ucla.edu/ energy-design-tools

Florida Solar Energy Center1679 Clearlake RoadCocoa, Florida 32922-5703Telephone: 407-638-1414 Facsimile: 407-638-1439E-mail: [email protected]: http://www.fsec.ucf.edu

SOLAR-5This program displays 3-D plots ofhourly energy performance for thewhole building or for any of 16 differ-ent components. SOLAR-5 also plotsheat flow into and out of thermal massas well as indoor air temperature, output of the HVAC system, cost ofelectricity and heating fuel, and the corresponding amount of air pollution.It uses hour-by-hour weather data. Itcontains an expert system to design an initial base case building for any climate and any building type, whichan architect can copy and redesign.Contains a variety of decision-makingaids, including combination and com-parison options, color overlays, and barcharts that show for any hour exactlywhere the energy flows.

Audience: This is for architects, studentsof architecture, building managers, andknowledgeable homeowners.

Expertise Required: It is intended to beself-instructional, with built-in helpoptions; requires only basic familiaritywith computers and with architecturalvocabulary.

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Input: From only four pieces of data initially required (floor area, number ofstories, location, and building type), theexpert system designs a basic building,filling in hundreds of items of data; theuser can make subsequent revisions,usually beginning with overall buildingdimensions, window sizes, etc.

Output: Dozens of different kinds ofthree-dimensional plots, tables, andreports. For example, displays heat gainor loss for more than a dozen differentbuilding components; shows heat flowinto and out of the thermal mass of thebuilding, as well as the output of theheating and air conditioning systems;displays air temperatures (outdoors orindoors) and air change rates; predictsthe cost of heating fuel and electricity.

Strengths: Intended for use during the very earliest stages of the designprocess (when most critical energydecisions are made); extremely userfriendly and rapid, calculating a fullyear using TMY data in less than aminute on a 486 MB machine.

Weaknesses: Not intended for complexmechanical system design or equip-ment sizing.

Availability: SOLAR 5.4 is the mostrecent public release, updated inSeptember 1997. It writes out its ownusers manual. Not copy protected;sharing is encouraged. Most easilyaquired by copying a disk or by down-loading off the Web; otherwise, userscan send a check to the technical con-tact for $35, payable to the Regents ofthe University of California.

Contact: Professor Murray MilneDepartment of Architecture and Urban Design

Box 951467University of California at Los AngelesLos Angeles, California 90095-1467Telephone: 310-825-7370Facsimile: 310-825-8959E-mail: [email protected]: http://www.aud.ucla.edu/ energy-design-tools

SOMBREROIn designing both active (domestic hotwater, photovoltaics) and passive solarenergy systems, shading of collectors or windows by other objects plays animportant role. SOMBRERO providesquantitive solutions to these problems.It calculates geometrical shading coeffi-cients, which can be used either directlyfor visualization or as quantitativeinput to other thermal simulation programs.

Audience: Architects, engineers for ther-mal simulations of buildings or solarplants.

Expertise Required: Basic knowledge ofgeometry and solar radiation.

Input: Three-dimensional objects arebuilt up by their boundary planes. Upto 300 plane areas with 12 points eachcan be treated. Objects like houses andtrees are predefined and described byparameters like height, width, andposition in space. Single planes aredescribed by their vertex-points in thetwo-dimensional co-ordinate systemrelated to the plane itself (in case of rectangles simply by their length andheight) and positioned by indication of azimuth, elevation, and origin in thethree-dimensional space. Time steps for simulation can be selected freely.Foliage of trees and reflection factors of the ground can be given as monthlyschedules.

Output: Values of the daily course ofgeometrical shading coefficients are calculated hourly.

Computer Platform: MS-DOS 5.0 and MS-Windows 3.1 or better; PC-compatible system with VGA-compatible graphic-board (at least 640 x 480 pixels); about 5 MB free space on hard disk. The programminglanguage is Delphi.

Strengths: Easy to handle.

Weaknesses: Unknown.

Availability: A demonstration versioncan be downloaded free; it expires

5 days after it is first started up. The fullversion sells for $230.

Contact:Prof. Dr.-Ing. F.D. Heidt Building Physics and Solar Energy University of Siegen Siegen, 57068GermanyTelephone: +49 271-740-4181 Facsimile: +49 271-740-2379E-mail: [email protected]

Web: http://nesa1.uni-siegen.de

SUN POSITION The program calculates time series ofsun angles (such as solar altitude andsolar azimuth) for a given location andoutputs them as text files that can beimported into spreadsheets and solarenergy analysis programs. Sun Positionis highly customizable; it can calculateangles for one specific day, once amonth for one year, once a week, daily,etc., and in a given day calculate theangles once a day, hourly, every 15 min-utes, etc. Its primary purpose is to assistarchitects and solar designers.

Audience: Architects, passive solardesigners, PV and solar thermal energysystem designers.

Expertise Required: Understanding offundamentals of sun angles (seewww.crest.org/staff/ceg/sunangle/for an introduction to sun angle concepts).

Input: The user inputs the geographicallocation, the frequency of the datadesired, and the output format desired;the program has a graphical user interface.

Output: The output is text files consist-ing of tables of sun angle data; the specific sun angles, format of the data,etc., are specified by the user.

Computer Platform: Windows andMacintosh; the programming languageis MacroMedia Director.

Strengths: Best for people performinganalyses of buildings or solar energy

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systems over a year who need to knowsolar altitude and azimuth angles fortheir analysis.

Weaknesses: While Sun Position cancompute individual sun angles (i.e., atone specific time instead of throughoutthe year), it would be more efficient touse the internet SunAngle calculator forsingle calculations.

Availability: Free.

Contact:Christopher Gronbeck Seattle Energy Works 1020 NE 68th Street Seattle, Washington 98115Telephone: 206-729-5260 Facsimile: 206-522-5051E-mail: [email protected] Web: http://www.energysoftware.com

SUNSPECThis software calculates clear-sky directbeam and diffuse-sky solar spectralirradiances and the sum of these twospectra for sun positions and atmos-pheric conditions specified by the user.Sunspec also calculates the spectralirradiances from the direct beam, dif-fuse sky, or ground reflections that areincident on an arbitrarily tilted plane.Sunspec integrates these spectra todetermine the total irradiances, illuminances, and luminous efficaciesfor each component.

Sunspec offers the user a menu of typi-cal atmospheric conditions to choosefrom and follows this with detailedediting screens permitting the user tochange any input parameter. The inputparameters include values for ozoneconcentration, water vapor, turbidity,ground reflectance (albedo), solar alti-tude and azimuth angles, and tiltedplane altitude and azimuth angles.Sunspec includes a loop option permit-ting repeated calculations at differentsolar positions for the same atmos-pheric conditions. It also has an optionfor outputting solar spectral data filesthat can be read by the Window 4 pro-gram, which calculates the solar optical

and heat transfer properties of win-dows in buildings.

Audience: This is for architects, build-ing designers, fenestration energy performance simulators, atmospheric scientists, and others interested indetermining the spectrum of radiationfrom the sun and sky.

Expertise Required: Basic understandingof solar geometry.

Input: User-friendly I/O screens, solarposition, atmospheric conditions.

Output: Results can be printed directlyto a printer, or saved to a print file or tofiles formatted for importing intographic plotting programs.

Strengths: Provides a solar spectrumdata file with columns for wavelength,direct normal, direct horizontal, directtilted, diffuse horizontal, and diffusetilted spectral irradiances, as well as theglobal (both direct and diffuse) versionsof these. Also outputs the integratedtotal irradiances in W/m2 and the totalintegrated illuminances in lux for allthese beams.

Weaknesses: Current menu of typicalatmospheric conditions is limited. Itdoes not yet have the latest version ofthe SMARTS algorithm and is not asuser-friendly as a planned future version.

Availability: Sunspec 1.0 is availablefrom the contact at a cost of $35 (including shipping and handling).

Contact:Joanne Sterling, Document Sales OfficeFlorida Solar Energy Center1679 Clearlake RoadCocoa, Florida 32922-5703Telephone: 407- 638-1414Facsimile: 407-638-1439E-mail: [email protected]: http://www.fsec.ucf.edu

TRNSYSThis modular system simulation soft-ware includes many of the componentscommonly found in thermal energysystems as well as component routines

to handle input of weather or othertime-dependent functions and outputof simulation results. TRNSYS(TRaNsient SYstem SimulationProgram) is typically used for HVACanalysis and sizing, solar design, build-ing thermal performance, and analysisof control schemes.

Audience: Engineers, researchers, andarchitects.

Expertise Required: None to use standardpackage; FORTRAN knowledge is help-ful for developing new components

Input: TRNSYS input file, includingbuilding input description, characteris-tics of system components and mannerin which components are intercon-nected, and separate weather data (sup-plied with program). Input file can begenerated by graphically connectingcomponents.

Output: Life-cycle costs, monthly summaries, annual results, histograms,plotting of desired variables (by timeunit), online variable plotting (as thesimulation progresses).

Strengths: Because of its modularapproach, the program is extremelyflexible for modeling a variety of ther-mal systems at different levels of complexity; supplied source code and documentation provide an easymethod for users to modify or addcomponents not in the standard library;extensive documentation on compo-nent routines, including explanation,background, typical uses and govern-ing equations; supplied time step, starting, and stopping times allowchoice of modeling periods. Version14.2 moves all the TRNSYS utility pro-grams to the MS Windows platform(95/NT), including a choice of graphi-cal drag-and-drop programs for creat-ing input files, a utility for easilycreating a building input file, and a program for building TRNSYS-basedapplications for distribution tononusers. Web-based library of addi-tional components and frequent down-loadable updates are also available.

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Weaknesses: No assumptions about thebuilding or system are made (althoughdefault information is available) so theuser must have detailed informationabout the building and system andenter this information into the TRNSYSinterface.

Availability: Version 14.2, Commercial,$4000; Educational, $2000. Free demon-stration diskette and information areavailable from the technical contact.International distributors are located in Germany, France, Belgium, andSweden in addition to two distributorsin the United States.

Contact: TRNSYS CoordinatorSolar Energy LaboratoryUniversity of Wisconsin1500 Johnson DriveMadison, Wisconsin 53706Telephone: 608-263-1589Facsimile: 608-262-8464E-mail: [email protected]: http://sel.me.wisc.edu/trnsys/download.htm

Appendix C: Design Tools 87

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Patrina Eiffert, Ph.D.Dr. Eiffert is a project leader in the NationalRenewable Energy Laboratory�s (NREL�s)Deployment Facilitation Center. NREL is a U.S.Department of Energy (DOE) national laboratory. As a Deputy Team Leader within NREL�s FederalEnergy Management Program (FEMP) team, Dr.Eiffert has had experience managing projects thatassist in implementing renewable energy in theFederal sector. Primary activities range from con-ducting economic feasibility analysis and designstudies through assessment and exploration of alternative financing mechanisms. Dr. Eiffert leadsnational activities under the Save with Solar: FederalParticipation in the Million Solar Roofs Initiative onbehalf of DOE FEMP.

Additionally, Dr. Eiffert co-represents the UnitedStates in the International Energy Agency,Photovoltaic Power Systems (PVPS) Task VII, Photovoltaics in the Built Environment, along withSteven Strong of Solar Design Associates. In thisposition, as an internationally recognized expert inBuilding Integrated Photovoltaics (BIPV), Dr. Eiffertleads the effort to develop International Guidelinesfor the Economic Evaluation of BIPV and is theActivity Leader for Subtask 3: Non-technicalBarriers.

Dr. Eiffert completed her doctorate in Architectureon building-integrated photovoltaics at OxfordBrookes University Post-Graduate Research Schoolin the United Kingdom. Dr. Eiffert has authoredmany articles and publications related to renewableenergy systems and programs and is a guest lecturerat universities across the country.

Patrina EiffertNREL, M.S. 27231617 Cole Blvd.Golden, CO 80401-3393

Gregory J. KissMr. Kiss, a specialist architect, has been a principal ofKiss + Cathcart since 1984. His work has focused onthe integration of solar technologies into architecureand product design, and has included built projectsresearch and education. Kiss + Cathcart have won anumber of awards and invited competitions, includ-ing top prizes in every solar-architecture competitionsince 1992. Kiss + Cathcart�s projects range fromfirst-of-a-kind photovoltaic buildings in Port Jarvis,New York, and Fairfield, California, to major PVbuildings projects in progress at Four Times Squarein Manhattan, New York; in Yosemite National Park;and in Hamburg, Germany.

Research by the firm has included three studies onbuilding-integrated photovoltaics commissioned by NREL. In conjunction with Energy Photovoltaicsof Princeton, New Jersey, Kiss + Cathcart has devel-oped several BIPV construction products, includinglarge-area lamiations for facades and skylights. Thefirm is also developing custom patterned, semitrans-parent PV panels for building use.

Consulting activities include the Whitehall FerryTerminal project in New York and solar housing inWinslow, Arizona, as well as the projects listed in the design briefs in this book.

Kiss + Cathcart designed "Under the Sun," a majorexhibition of solar design and architecture at theCooper Hewitt, National Design Museum,Smithsonian Institution. The exhibit is an investiga-tion of the design implications of the solar future;it was originally held in one of the most prestigiousgarden sites in the United States. This is now a traveling exhibit.

Gregory J. Kiss150 Nassau Street, Top FloorNew York, NY 10038

88 About the Authors

About the Authors

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NOTICE: This report was prepared as an account of work sponsored by an agency of the United Statesgovernment. Neither the United States government nor any agency thereof, nor any of their employees,makes any warranty, express or implied, or assumes any legal liability or responsibility for the accu-racy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United Statesgovernment or any agency thereof. The views and opinions of authors expressed herein do not neces-sarily state or reflect those of the United States government or any agency thereof.

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Available for sale to the public, in paper, from:U.S. Department of CommerceNational Technical Information Service5285 Port Royal RoadSpringfield, VA 22161phone: 800.553.6847fax: 703.605.6900email: [email protected] ordering: http://www.ntis.gov/ordering.htm

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