Presented by Tyler Stewart [email protected]/fileadmin/images/bifi/denver/... ·...

bifiPVWorkshop–September10th,2018:Denver,Colorado

BifacialCommercialInstallationswithImprovedBifacialGains

[email protected]


Outline

• WhoisPrismSolarTechnologies?• Quickoptimizationmethod• Whatistheissuefacingtheoptimizationofbifacialsystems?

•  BifacialCommercialWhiteRoofs•  BifacialCarportSystems•  Conclusions


PrismSolarTechnologiesInc.

•  PrismSolarTechnologieswasfoundedin2005.•  Researchingbifacialandholographic/bifacialtechnologyandapplicationssince2006(Hitachicells);sixawardedpatentsinbifacialtechnologyandapplications.

•  Commerciallysellingbifacialmodulessince2012.


DesignOptimizationWithModelBGE’(%) = (0.317/deg*(θ)+12.145/m*(h)+0.1414/%*(α)) * (BR’[%]/95%) *(Azimuth Correction Factor(%)) * (Inter-row Correction Factor(%)) * (1-η(%))

θ = Module Tilt Angle (deg) h = Module Minimum Height/Elevation (m) α = Ground Albedo/Reflectance BR’ = Bifacial Ratio, or Bifaciality of the Module η  = Rear Obstruction Factor (%)

Total Bifacial System Energy Yield [%] = Monofacial*(BGE’(%) + 100%)

Azimuth Correction Factor =0.0000822*(φ^2)-0.0005129*(φ)+0.9988

φ=Azimuthdeviationfromsouthinnorthernlatitude(deg.) Inter-row Correction Factor =(-0.0467*(t)+1.42)*100%;max=100%,min=86%

t=TimeusedforDec21stShadowLengthCalculationsforinter-rowspacingdetermination;between9amand12pm.PrismSolarModelReference:J.E.Castillo-AguilellaandP.S.Hauser,"Bifacialphotovoltaic module best-fit annual energy yield model with azimuthalcorrection," 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC),Portland,OR,2016,pp.3109-3112.doi:10.1109/PVSC.2016.7750238

AgoodmatchhasbeenfoundbetweenthePrismSolarannualbest-fitmodelandtheannualresultswith PVSyst 6.70 for the high bifacial gainsregionsofinterestofthispresentation.

**Use your preferred model toestimate bifacial gains for yourdesign**


OptimizingtheBifacialGain:Issue

MaximizingthebifacialgainbeyondcertainvaluescansignificantlyincreasethecostofthebifacialsystemBifacialgainsreachsaturationpointsatcertainheightsandtilts.Thisisespeciallytrueinareaconstrainedinstallationsites.

Maximumbifacialgainsleadtocostincreasesthatarenotcompensatedbythepeakachievablebifacialgain.Lawofdiminishingreturns


ExamplesofBifacialInstallationsinLiterature

TableSource:Sun,Xingshu,Khan,MohammadRyyan,Deline,Chris,andAlam,MuhammadAshraful.Optimizationandperformanceofbifacialsolarmodules:Aglobalperspective.UnitedStates:N.p.,2018.Web.doi:10.1016/j.apenergy.2017.12.041.


BifacialCommercialWhiteRoofCommercialRooftopAndBifacialModules:•  Higheralbedo•  Highertiltacceptable•  Increasedmoduleheight(advantageinsnowyregions)•  Optimizers/Microinverter[*](Otherbuildingcodebenefits)DetrimentalSystemConsequences:•  Areaconstrained,lowersystemGCRduetohighertilt•  Lackofwinddeflector&atthehighermoduletiltand

heights,rackingcostscanbecomeprohibitive.•  Optimizingthebifacialgainleadstolessmodulesinstalled

[*]: Riley, D. et al. 2018 Performance of Bifacial PV Modules with MLPE vs. String Inverters, WCPEC-7, Waikoloa, HI.


BifacialOptimizedRackingExamples

Additionalbracingforextraheightandsnowloads

Uprightrackingelementscanbereducedinquantity,reducingthesystemcosts,increasingtheRearObstructionFactorforthebifacialmodule.Alternative,thecross-railscanbestrengthenedtoreducethenumberofuprights,butthisalsoincreasesthesystemcost. Rearobstructionfactorsof4%

to5%arerelativelyeasytoobtainwithcarefuluprightplacement,buttryingtoachieve0%to2.5%mightbecostprohibitivefromarackingperspective.


WhiteRoofsBifacialRecommendations•  Min.TiltAngle=10degrees;Max.TiltAngle=30degrees•  Min.ModuleElevation=0.3m;Max.ModuleElevation=0.5m,

or0.6mforsnowregions•  Min.InitialRoofAlbedo=75%(Albedodecreaseswithtime)•  Min.Inter-rowspacing=11am•  Min.recommendedrearObstructionFactor=3%•  Max.recommendedrearObstructionFactor=8%

Usingallthesevaluesattheworstcondition,andusingthePrismSolarbifacialmodel,thisstillyieldsa~14%BifacialGainwitha90%Bifacialitymodule.

Thebifacialgainwouldbedirectlyreducedifthemodulebifacialityisreduced.


154.3kWBifacialUpstateNYInstallation


Component Model Rating(W) QTY Specifications/Manufacturer’sWebsite:Module Bi60-368BSTC 290WDC 532 http://www.prismsolar.com/pdf/bi60specs.pdfOptimizer P730 730WDC 266 http://www.solaredge.com/sites/default/files/se-P5-series-

commercial-add-on-power-optimizer-datasheet-na.pdfInverter SE33.3KUS 33,300WAC 5 http://www.solaredge.com/sites/default/files/se-three-phase-us-

inverter-datasheet.pdfRacking SunrailBifacial - - http://opsun.com/mounting-solutions/flat-roof/bifacial-pv-

racking/

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0

25000

50000

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100000

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150000

175000

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System

Produ

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SystemandAverageModuleProduction(InverterLimited)

15minSystemProduction(W)

15minAVGSystemProduction/module(W)

Clientsupplieddatasystem:Basedonthemodulesandinverters,thesystemhasaDC/ACratioof0.927Inter-rowspacing11am,Albedoof+75%,systemtiltof30degrees,Azimuth=10degreesfromsouth,andRearObstructionFactorof~5%.Oncetheoptimizerscapped,themoduleswereproducing12.7%to21.45%overSTC.UsingthePrismSolarModel+PVSystforthefrontyieldsayearlyoutputof1633.5kWhac/kWdc.ThePVSystbifacialmodelV6.70yields1657kWhac/kWdc.




Clippingwas

Observed


Themedianannualproduction,usinga12-monthaveragingwindowis1633.9kWhac/kWdc.MedianPR=1.025

154.3kWBifacialUpstateNYInstallationThesystemwasturnedonafewmonthsbeforetheirradiancesystem/PRsystemwasputinplace.ThehighestPerformanceRatio(PR)coincideswithlowestdailykWh/kW,andvice-versa.

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Performan

ceRatio(P

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DailyEne

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DailyEnergyProductionforthe154.3kWBifacialSystem(532Modules)DailySystemProduction(kWh/kW)PerformanceRatio(Bi60-290W)14per.Mov.Avg.(PerformanceRatio(Bi60-290W))


CommercialRooftop•  Bifacialrooftopandcarport

systeminQuebec,Canada.•  30Degreemoduletilt•  Elevation=0.42m•  EstimatedBifacialGain=+20%•  OwnerdatasinceJuly2018


BifacialCarportsCarportAndBifacialModules:•  Highercarportmodule/systemheight•  East/WestConfigurations•  UsuallynotGCRconstrained•  Aligningthemoduleslongedgeswiththestructurepurlins,reducesthe

RearObstructionFactor.

DetrimentalSystemConsequences:•  Rackingcostsincreasewithcarportheightandtiltanglesover+10degrees•  GroundReflectance/Albedoinmostcasesbetween8%(FreshAsphalt)

-20%,rarelyexceeds40%.•  Increasingtheheightortiltangleexcessively,canreducethecarport

shadingeffectforthevehiclesunderthestructure.


BifacialCarportsRecommendations

•  Min.TiltAngle=7degrees;Max.TiltAngle=20degrees•  Min.ModuleElevationRatio=0.3•  Max.ModuleElevationRatio=0.6•  Max.recommendedrearObstructionFactor=10%

Usingallthesevaluesattheminimum/worstcondition,Albedo=10%,andusingthePrismSolarbifacialmodel,thisstillyieldsan~6%BifacialGainwitha90%Bifacialitymodule.Thisincreasesto~10%foranEast/Westinstallation.

Thebifacialgainwouldbedirectlyreducedifthemodulebifacialityisreduced.


BifacialCarportExample

Carportsystemdesignedinsuchamannertominimizetherearobstructionfactor,modulealignedwithpurlins,andthemajorstructureelementsareplacedintheplaceswheremodulesmeet.


BifacialCarportExample

• ElevationRatio=~0.5• +600kWBifacialcarportsysteminQuebec,Canada.

• MostlyE/Waligned• DatasinceJuly2018


9.72kW(36modules)DC/ACratio=1.28(capsMay-Aug)BifacialRatio=90%Azimuth=EastFacingHeightRatio=0.5Tilt=7degreesAlbedo/SR=40%EstimatedBifacialGain:21.4%Ownerprovideddata

BifacialCarport–TucsonAZ(2Yeardata)

Theaveragemeasuredannualenergyproductionforthe2yearperiodwas1817.9kWhac/kWdc

TheaveragedGainmeasuredforthe2yearperiodwas19.6%,justunderthepredicted21.4%.


Conclusions•  Significantbifacialgain’sareobtainableinvariousrealworldapplications

•  MaximizingBGEgenerallydoesnotmakefinancialsense

•  Financialoptimizationisthekey•  Allthesitevariablesmustbeconsideredwhendesigningthesystem.Thisincludescostofelectricity


ThankYou

Additionalquestions:[email protected]@prismsolar.com

Presented by Tyler Stewart [email protected]/fileadmin/images/bifi/denver/... ·...

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