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INTERIMREPORT

LongTermOutputof

Grid-TiedSolarElectricSystems

byEverettM.Barber,Jr.

everett.barber@gmail.comApr.27,2020

BasisforPerformanceComparison

• EnergyProducedperyear/systemcapacity:– kWh(ac)peryr/kW(dc)– Numericalexample:

• 3973kWh(ac)peryr/3.750kW(dc)=1059.5kWh(ac)peryr/kW(dc)

• EnergyProducedperyear/collectorarea:– kWh(ac)peryr/ft²;or/m²– Numericalexample:

• 3973kWh(ac)peryr/311.9ft²=12.7kWh(ac)peryr/ft²or,• 3973kWh(ac)peryr/28.9m²=137.5kWh(ac)per/m2

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3

0

200

400

600

800

1000

1200

1400

kWhac/yr/kW

dc

System/kWdc/yearsdata/Celltype

Grid-TiedSolarElectricSystem OutputAvg.for18Fixed MountWorkingSystems- SouthernNewEngland

Avg.ofallfixedsystems=1149kWhac/yr/kWdc

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0.0

5.0

10.0

15.0

20.0

25.0

kWhac/yr/ft2

System/kWdc/yearsdata/celltype

Grid-Tied SolarElectricSystem OutputAvg.for18Fixed MountWorkingSystems- SouthernNewEngland

16.3kWhac/yr/ft2 (170.5kWhac/yr/m2)

Noneofthesesystemshavemicroinverters.

0.0

5.0

10.0

15.0

20.0

25.0

kWhac/yr/ft2

KEY:System/kWdc/yearsdata/celltype

Grid-Tied SolarElectricSystem OutputAvg.forall26Fixed MountSystems- SouthernNewEngland

--- 14.6kWhac/yr/ft2 (157.1kWhac/yr/m2)

19.3

23.1

0.0

5.0

10.0

15.0

20.0

25.0

kWhac/yr/ft2

10Yr.Avg.Output

10YearAveragedActualOutputCommercialSystems

OneFixed&OneSingleAxisTrackingmodularcollectors,WestHartford,CT

'fixedarray'

'trackingarray'

6

20.2

23.6

0

5

10

15

20

25

1YR- PVWATTS

kWhac/yr/

ft2

1YearOutputForecastPVWATTSv1CommercialSystems

OneFixed&OneSingleAxisTrackingmodularcollectors,BradleyAP,CT(TMY2)

fixedarray

trackingarray

7

PVWATTsv1Input

DefaultParameters 2010ago presentday

tilt(deg.) 35 20

module std std

mount fixed fixed

azimuth 180 180

syslosses% 22.00 14.08

invertereff% 96% 96%

8

0200400600800

100012001400160018002000

kWhac/yr/

kWdc

ProjectedOutput(PVWATTSv1)FixedMountArray

selectedcities(w/parametersonpriorslide)

9n.b. Thepresent‘default’parametersforPVWATTSyieldoutputs~10%higherthanobservedhere.

Calc.avg;(omitAlbuquerque,LA&FRG.)Hartford,CT 1159 kWh ac/yr/kw dcBridgeport,CT 1197Boston,MA 1239NY,NY 1239Wash,DC 1234Jacksonville,FL 1271Chicago,IL 1184DesMoines,IA 1239Salem,OR 1104Louisville,KY 1231Houston,TX 1208

Σ 13305avg. 12105%+ 12705%- 1149

Avg.forFixedMountArray.(PVWATTsv1)PVWATTSoutputiswithin±5%ofcitiesshown

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12

13

-40.0%-30.0%-20.0%-10.0%0.0%

10.0%20.0%30.0%40.0%50.0%

C(11

)aD(11)a

E(10

)aF(1)b

G(9)a

H(4)a

I(10)a

J(13)b

K(8)a

L(8)a

M(6)a

N(4)a

O(8)b

P(7)c

R(8)a

T(10

)a

V(11)a

W(12)a

X(12

)aY(9)a

Z(11

)bAA

(1)a

AB(12)a

AC(4)b

AD(9)a

AF(12)b

AG(11)d

AI(4)b AJ AK

GainD

eterioratio

n(20yrs)

KEY:System(#yearsdata)CellType

SolarElectricSystem OutputDeterioration18Fixed-MountSystems- SouthernNewEngland

%deteriorationprojected to20yearsbasedonsystemagein()belowCellTypes:a: singleormono-crystallineb.multiorpolycrystallinec.amorphousd. semi-crystalline

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Afewsystemswithnegative%(gain)hadpooroutputduringearlyyearsofuse.Nodataforsomesystemssincedatanolongeravailablefromsys.owners.

ExampleOutputProjection

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y=-22.037x+1190

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

kWh/yrac/kW

dc

Years

14yearoldsystemyearlyvariationofoutput

kWh/yr ac/kWdc

n.b. AboveequationgeneratedbyEXCEL’sTrendline function

eqn. y=-23.257*X +1333.2solve for y year # years % Loss

1309.943 2006 11263.429 2008 3 3.6%1216.915 2010 5 7.1%1100.630 2015 10 16.0%868.060 2025 20 33.7%

means projection

Solve Equation for %Lossoutput decay

EstimatingLongTermOutputLoss

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n.b. aboveequationgeneratedbyEXCEL’sTrendline function.

CausesforSystemOutputDeterioration

• Inverter:(warrantylength:5yrs;10yrs.)• Inattentiontooutputloss;procrastinationwhenfound• Difficultyinfindingaservicecontractor• Treegrowth• Incorrectstringfuseresistance• Inverterfusedamagecausedbylightning• Squirrelsshortingstring(wire)insulation.• LongTermCellDeterioration• Systemoff:variousreasonsgen.wasrun;bldg.vacant;etc.• SystemRemovedorabandonedbyowner

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0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

C D E F G H I J K L M N O P Q R S T U V W X Y Z AA AB AC AD AF AGAH AI

%EFF

System

SolarElectricCollector EfficiencyWhenNew28Systems(mfg.data)

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Andalay ST170-1AstroPower AP-100AstroPower AP-110BP3125SCanadianSolarCS6P-230PEvergreenEC115Kyocera210Sanyo195Sanyo200SanyoHIP-200BA3SanyoHIP-200BA4

Schuco S180-SPU-4Schott300Sharp175Sharp175ShellSolarPowerMaxSQ-165SunPower 215SunPower SPR-210-WHTUnisolar ePVL-144SunPower SPR-215

PVModuleMfg's inthiscompilationofsystems

Linedthru:OutofBusinessRedText:Solarbiz:SoldtoPanasonic

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Other1Yr.Studies

• See:1. http://www.nrel.gov/docs/fy12osti/51664.pdf

AnNRELreviewoftheliterature datedJune2012.

2. https://openpv.nrel.gov/AnNRELcompilationofPVSystemsthroughouttheUS.Includessomeoutputdata;costs;etc.

• Noreferenceswerefoundthathavecompiledmulti-yeardata.

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