The Solar Resource

Overview

• Overview of the solar resource in the U.S. • Features impacting solar irradiance

» Latitude, cloud cover, seasonality• Converting power to energy• Tools to measure solar energy and shading• An overview of solar energy systems

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Solar PV

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Germany47%

Spain23%

Japan8%

USA8%

Rest of EU6%

Rest of world8%

World PV market in 2007, 2826 MW total

Solarbuzz LLC.

So Germany must be sunny, right?

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Measuring the solar resource

• Magnetic declination• Solar pathways• Solar math (power to energy)• Latitude and curvature• Air currents

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What impacts solar gain each day?

Latitude (winter solstice)

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Sun Path – New York

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Winter Solstice

Equinox

Summer Solstice

This angle should be equal to your latitude

Magnetic Declination

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http://sos.noaa.gov/images/Land/magnetic_declination.jpg

True south and declination

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Declination corrections

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Magnetic NorthTrue North

True South

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Solar Angles by month in Morrisville

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What impacts solar gain each day?

• Latitude

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Morrisville’s Solar Resource

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Month Mean W/m2/day kWh/m2/day

January 63.8February 98.8

March 140.9April 182.1May 220.5June 231.5July 224.2

August 203.0September 159.6

October 101.0November 59.3December 44.7

Morrisville’s Solar Resource

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kWh/m2/day =Month Mean W/m2/day kWh/m2/day

January 63.8February 98.8

March 140.9April 182.1May 220.5June 231.5July 224.2

August 203.0September 159.6

October 101.0November 59.3December 44.7

Morrisville’s Solar Resource

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Month Mean W/m2/day kWh/m2/day

January 63.8 1.5February 98.8 2.4

March 140.9 3.4April 182.1 4.4May 220.5 5.3June 231.5 5.6July 224.2 5.4

August 203.0 4.9September 159.6 3.8

October 101.0 2.4November 59.3 1.4December 44.7 1.1

kWh/m2/day =

Yearly mean power?• 144.1 W/m2/day

Yearly mean energy?• 3.5 kWh/m2/day

Wh1000

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Solar energy throughout the year

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Solar Energy

MSC weather station data

How does central NY compare?

• Average of solar energy throughout the year is 3.5 kWh/m2/day. » This is 1277.5 kWh/m2/year (365 days * 3.5 per

day)» Albany has a daily average of 4.3 kWh/m2/day

(1569.5 kWh/m2/year)» San Diego has 7.3 kWh/m2/day (2664.5

kWh/m2/year)

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Solar energy

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Cloud cover

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Air Cells

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Low pressure

High pressureDeserts(sunny)

Rain Forests (cloudy)

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Global Solar Energy

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Solar energy systems

• If you assume that systems costs are comparable in NY and southern California, which location has more expensive solar energy?

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Estimating the Solar Resource

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Estimating the Solar Resource

Estimating the Solar Resource

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Estimating the Solar Resource

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June (lowest line): 1+1+2+2+3 = 9%July (next up): 1+1+2+3+3 = 10%May: 1+1+2+3+3 = 10%August: 1+1+2+2+3 = 9%April: 1+2+2+3 = 8%September: 1+2+2 = 5%October: 1%

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Estimating the Solar Resource

Month kWh/m2/dayPercentage

Lost Daily

Energy Monthly Energy

January 1.5 0 1.5 46.5February 2.4 0 2.4 67.2

March 3.4 0 3.4 105.4April 4.4 8% 4.048 121.44May 5.3 10% 4.77 147.87June 5.6 9% 5.096 152.88July 5.4 10% 4.86 150.66

August 4.9 9% 4.459 138.229September 3.8 5% 3.61 108.3October 2.4 1% 2.376 73.656

November 1.4 0 1.4 42December 1.1 0 1.1 34.1

Total annual energy 1188.24

Solar energy systems

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Photovoltaics

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Solar Thermal Electricity

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Parabolic mirrors

Solar Hot Water

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Domestic solar hot water system• Flat plate collector (low temp)• Evacuated tubes (higher temp)• Solar hot water tank with heat exchanger

Images courtesy of John Siegenthaler

Passive Solar Heating

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Large windows facing south

Conifers to the north

Small windows to north

Thermal mass

Summary

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• New York has an adequate solar resource for solar PV, solar hot water, and passive solar homes

• Solar power can be easily converted to solar energy (and we can account for shading)

• Incoming solar energy is affected by many factors such as latitude, cloud cover, and time of year

• Many systems can take advantage of solar energy

Phil Hofmeyer, Ph.D.Assistant ProfessorPh: 315-684-6515Email: hofmeypv@morrisville.edu Web: http://people.morrisville.edu/~hofmeypv/

Ben Ballard, Ph.D.Director, RETCAssistant ProfessorPh: 315-684-6780 Email: ballarbd@morrisville.edu Web: http://people.morrisville.edu/~ballarbd/

Contact Information

http://retc.morrisville.edu