P14421: Smart PV PanelBobby Jones: Team LeaderSean KitkoAlicia OswaldDanielle HoweChris Torbitt

AGENDA

•Project Overview•Heat Analysis•Electrical Design•System Layout•Test Plans•BOM•MSD II Schedule

Project Overview

•Advance Power Systems▫Jasper Ball▫Atlanta, GA

•Snow reduces power output of PV panels•Develop method to prevent snow from

accumulating in the first place▫Apply current to conductive, heating ink▫Keep temperature of panel surface above

freezing▫Sense presence of snow

Project Overview

Heat Analysis

Heat Analysis Process

•1 How much power is produced by the panel if there was no snow▫Uses TMY3 data which is the most average

months weather in Rochester▫Calculates solar beam angles on panel

based on time of day and day of year and angle of panel tilt

▫Calculate how much energy panel produces from TMY3 data, solar beam angle, efficiency of panel (19%) and area of panel (0.024m)

Heat Analysis Process con’t

•2 Find energy required to heat the panel in between ink traces to 5°C▫Length and spacing determined by cell

size. Limited to where bus bars on cells were

▫Coefficient of convection (h) ranges from 5 to 28

▫Modeled sections of cell using fin analysis▫Was able to calculate m, to get temperature

at ink and qfin

Cell

Heat Analysis Process con’t

•3 Calculate total energy ▫qfin values already calculated

▫Calculate qmelt based on an average snowfalls rate over 4 hours Uses ice properties (h=33400J/kg) Assumes density of snow=60 kg/m2

▫Calculated qrad

Uses glass properties and surrounding temperature

▫Total qgen is the sum of these in each section

Heat Analysis Process con’t

•4 Compare different ink configurations based on qgen calculation▫qgen was calculated based on sections of a

cell▫Calculations for configs based on an entire

panel, not just one cell▫Conclusion: Configuration 2 is the more

efficient in all cases

Configuration 116 Sections8-0.013 Sections8-0.052 sections

Configuration 28 Sections8-0.039 Sections

Configuration 34 Sections4 0.078 Sections

Configuration 410 Sections4-0.031 Sections4-0.052 Sections2-0.029 Sections

Heat Analysis Process con’t

•5 calculated specific convection coefficient for each hour of the day it snows▫Uses TMY3 data▫Does not take into account the direction of

wind or the angle of panel▫Temperatures all rounded to nearest

degree ▫Conclusions: All Reynolds's numbers were

<5*105 therefore all used laminar model

Heat Analysis Process con’t

•6 calculated energy required for snow prevention on panel▫Uses h that was calculated▫Uses same process as qgen calculation but

uses data for that specific day▫Snow data could not be found on hour

basis, so assumed snows for four hours when most energy could be generated

Heat Analysis Process con’t•7 find how much light gets to the panel

when snow is left to accumulate▫Uses equation found on next slide▫Equation used when there is snow

accumulation.▫As time moves forward, the snow accumulates▫Snow is assumed to be left on panel for the

rest of the day▫Each day it is assumed there is not snow

starting on the panel

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.50

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100f(x) = − 10.5295788625791 ln(x) + 27.2693484173735

Series1Logarithmic (Series1)

Snow Depth (cm)

Perc

enta

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Percentage of Light vs. Snow Depth

Heat Analysis Process con’t

•8 Graphically compare results▫Took the amount of energy required to melt

snow over four hours (when there was snow) and subtracted that from how much energy the panel would produce with no snow

▫Took the calculated amount of light that would get through the snow and graphed that

January 2

0:00 4:48 9:36 14:24 19:12 0:00 4:48

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February

Energy Total Prevention (J)Energy Total Accumulation (J)

Energy Conclusion:•Total energy for one year if snow is

prevented: -7.5*107J (-20,823Wh)•Total energy for one year if panel was left

alone: about 3,300,000J (916.5Wh)•Snow prevention is not the best way to

get rid of snow from an energy standpoint•Suggest seeing energy consumption if

snow is allowed to accumulate then heated up to slide off. Only found through testing.

Heat Analysis: ANSYS Modeling

ANSYS ModelingGoals:

• Utilize ANSYS modeling to verify Alicia’s analysis• Compare various ink layouts for efficiency of heat spread

Process:• Made models in ANSYS representing various ink pattern layouts• Modeled numerous scenarios• Based on 5”x 5” cells that will be used in prototype

Assumptions:• Convection on back of panel can be neglected due to

insulation/lack of exposure• Thermal conductivity of glass = 1.4 W/m2

• Thermal conductivity of ink = 300 W/m2

Variables::• Ink temperature (Ranges from 20-45°C)• Bulk temperature (Ranges from -10 to 0°C)• Convection coefficient (Ranges from 8 to 22 W/m2-K)

Ink Layout 1• Represents squares

of ink in corners between cells.

• Approximately 1 cm2 of ink at each location

• Poor heat spread, inefficient.

• Majority of cell at -5°C, overall regardless of ink temperature.

Layout 1: h=12W/m2, Tink=45°C, Tbulk=-5°C

Layout 1: h=12W/m2, Tink=30°C, Tbulk=-5°C

Ink Layout 2• Represents a

zigzag pattern of ink around all edges of cells.

• Heat doesn’t spread to center.

• Center of cell at -2°C with ink at 45°C

• Not efficient.

Layout 2: h=12W/m2, Tink=45°C, Tbulk=-5°C

Layout 2: h=12W/m2, Tink=25°C, Tbulk=-5°C

Ink Layout 3• Represents having 2

mm thick lines of ink between cells.

• Isn’t effective for allowing heat to spread across entirety of cell.

• Majority of cell still at -4°C

Layout 3: h=12W/m2, Tink=25°C, Tbulk=-5°C

Ink Layout 4• 2 mm lines of ink

between cells, 1.5mm line down center of cells.

• Most conducive to successful heat spread.

• Increasing convection along with lower bulk temperatures can lead to issues.

Layout 1: h=12W/m2, Tink=45°C, Tbulk=-5°C

Layout 4: h=14W/m2, Tink=25°C, Tbulk=-10°C

Layout 3 vs. Layout 4

• Comparing having a center line of ink across cells vs. not

– Apparent that the extra line allows for much better heat spread.

• Verifies that 3 line pattern is best option.

Layout 4: h=12W/m2, Tink=25°C, Tbulk=-5°C

Layout 4: h=12W/m2, Tink=25°C, Tbulk=-5°C

Effects of Adjusting Variables

• Heat spread most affected by increased convection rather than decreasing ambient temperature.

Layout 4: h=12W/m2, Tink=25°C, Tbulk=-10°C

Layout 4: h=18W/m2, Tink=45°C, Tbulk=-10°C

Electrical Design

Sensors

Simulations

Power Electronics

Power Usage

Don’t want the battery to go below 40% Capacity

Takes into account Efficiency in Cold Temperatures

Power Management

Item Current (A) Voltage (V) Time (Hrs) Power (W) Amp Hrs

Ink 10 8 4 82 40

MicroController 0.0002 3.3 24 0.00066 0.0048

Charge Controller 0.01 12 24 0.12 0.24

OPIC Light Sensor 0.0005 3.3 24 0.00165 0.012

LM35 Temp sensor 0.00005 5 24 0.00025 0.0012

Thermocoupler amplifier 0.0002 5 24 0.001 0.0048

Totals 82.12356 40.2628

Needed Battery Capacity Efficiency in Cold Choose battery

64.42048 60% 103.072768

Power Electronics Schem

Solid State Relay

Regulators•BP5275 Series

• MAX1681

Battery and Controller• Trojan 31-AGM Battery• Getting a free AGM battery from a

contact at Renewable Rochester

• Morningstar SS-20L 20 Amp PWM Solar Charge Controllers w/LVD ($78)

POC CONTROL SYSTEM

• Atmel's ATMega328P 8-Bit Processor in 28 pin DIP package with in system programmable flash

Features:•32K of program space•23 programmable I/O lines 6 of which are channels for the 10-bit ADC. •Runs up to 20MHz with external crystal. •Package can be programmed in circuit. •1.8V to 5V operating voltage•External and Internal Interrupt Sources•Temperature Range: -40C to 85C•Power Consumption at 1MHz, 1.8V, 25C

–Active Mode: 0.2mA–Power-down Mode: 0.1μA–Power-save Mode: 0.75μA (Including 32kHz RTC)

POC CONTROL SYSTEM Con’t

POC CONTROL SYSTEM Con’t

POC CONTROL SYSTEM Con’t

POC SENSOR RESEARCH

Enclosure

Enclosure and Layout

BILL OF MATERIALS

Risk Assessment and Mitigations

TEST PLAN OUTLINE

MSD II SCHEDULEP14421 MSD II – Tentative Schedule Weeks 1-3: • MSD I issues summarized. Mitigation strategies implemented (Jan

28th)• Comprehensive and detailed Test Plan completed (Jan 28th)

• Test and Prototype components and systems• Create preliminary C-Code for systems controller• Begin construction and customization of enclosure Weeks 4 and on: • Detailed/Finalized Testing• Iterative testing and refinement of system and subsystems• Technical paper and poster• Confirm deliverables have been met