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Types of PV panels and systems
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1Handbook for Solar Photovoltaic (PV) Systems
Contents
1 Solar Photovoltaic (PV) Systems An Overview 4 1.1 Introduction 4 1.2 Types of Solar PV System 5 1.3 Solar PV Technology 6 CrystallineSiliconandThinFilmTechnologies 8 ConversionEfficiency 8 EffectsofTemperature 9 1.4 Technical Information 10
2 Solar PV Systems on a Building 12 2.1 Introduction 12 2.2 Installation Angle 12 2.3 AvoidShadingPVModules 13 2.4 AestheticandCreativeApproachesinMountingPVModules 14 2.5 SolarPVOutputProfile 14 2.6 Solar PV Yield 15 2.7 CostofaSolarPVSystem 15
3 Appointing a Solar PV System Contractor 16 3.1 Introduction 16 3.2 Getting Started 17 GetanExperiencedandLicensedContractor 17 ChoosingBetweenBids 17 SolarPVSystemWarranty 17 RegularMaintenance 19 OtherRelevantMatters 19
4 Solar PV System Installation Requirements 20 4.1 ElectricalInstallationLicence 20 4.2 ElectricalSafetyStandardsandRequirements 20 4.3 ApplicationofElectricalInstallationLicence 21 4.4 ConservationandDevelopmentControlRequirements 21 4.5 GuidelinesonConservationandDevelopmentControl 21 4.6 StructuralSafetyandLightningProtection 22 StructuralSafety 22 LightningProtection 22 4.7 ConnectiontothePowerGrid 22 4.8 GetConnectedtothePowerGrid 23 4.9 SaleofSolarPVElectricity 23 Non-residentialUser 23 ResidentialUser 25 4.10 DesignandInstallationChecklist 26
5 Operations and Maintenance 28 5.1 OperationsofSolarPVSystems 28 5.2 RecommendedPreventiveMaintenanceWorks 29
1Appendices
APPendIx A exAMPleS Of SOlAR PV SySteM On BuIldIngS In SIngAPORe A.1 ZEROENERGYBUILDING@BCAACADEMY 32
A.2 POHERNSHIH(TEMPLEOFTHANKSGIVING) 34
A.3 313SOMERSETCENTRAL 36
A.4 SENTOSACOVE 38
A.5 MARINABARRAGE 40
A.6 LONZABIOLOGICS 42 A.7 ZEROENERGYHOUSE 44
A.8 TAMPINESGRANDE 46
A.9 HDBAPARTMENTBLOCKSATSERANGOONNORTHPRECINCT 48 A.10 HDBAPARTMENTBLOCKSATWELLINGTONCIRCLEPRECINCT 50
APPendIx B B.1 ENGAGINGALICENSEDELECTRICALWORKER 52
APPendIx C C.1 CONTACTINFORMATION 54
APPendIx d InCentIVeS fOR SOlAR PV SySteM D.1 SOLARCAPABILITYSCHEME(SCS) 55
D.2 MARKETDEVELOPMENTFUND(MDF) 56
D.3 GREENMARKSCHEME 57
D.4 GREENMARKGROSSFLOORAREA(GM-GFA)INCENTIVESCHEME 58
D.5 $100MILLIONGREENMARKINCENTIVESCHEME 59 FORExISTINGBUILDINGS(GMIS-EB)
D.6 ENHANCED$20MILLIONGREENMARKINCENTIVESCHEMEFOR 60 NEWBUILDINGS(GMIS-NB)
2Cognizantofthegrowingpopularityofsolarphotovoltaic(PV) installationsamongstresidentialdwellersaswellasbuildingdevelopers,and thecorrespondingdemand foracomprehensivesetoftechnicalandregulatoryinformation,theEnergyMarketAuthority(EMA)andtheBuildingConstructionAuthority(BCA)gottogetherearlierthisyeartoworkonintegratingtheirrespectivesolarmanuals intoanall-in-onereferenceguidefor thosewhoarekeenon installingsolarPVsystems in Singapore.
The outcome of this joint project,which also saw the involvement of industry partners andstakeholderssuchasPhoenixSolarPteLtd,GrenzonePteLtd,SolarEnergyResearchInstituteofSingapore(SERIS)andSingaporePolytechnic, isthisHandbookforSolarPhotovoltaic(PV)Systems. Through this integrated and revised handbook, we hope to be able to provide acomprehensiveguidetotherelevantparties,includingowners,developers,engineers,architects,Licensed ElectricalWorkers and electricians on the key issues, requirements and processespertaining to the installation of solar PV systems.
Aswiththepreviouseditionofthehandbooks,thissinglevolumecoversandprovidesinformationonlicensing,marketandtechnicalrequirements,andbuildingandstructuralissuesthatarerelatedtotheimplementationofsolarPVsystemsinabuildingenvironment.Inaddition,itprovidesnewinformationontheinstallationrequirementsforsolarPVsystems,operationsandrecommendedpreventivemaintenanceworks,andvariousincentivestopromotesolarPVsystemsinSingapore.Wehavealsorefreshedthepresentationofthehandbooktomakeitmoreaccessibleandreader-friendly,aswellastoincorporateexamplesofcompletedsolarPVinstallationsinSingapore.
Wehopeyouwillfindthistobeausefulguide.
david tan Ang Kian SengDeputy Chief Executive DirectorEnergyPlanningandDevelopmentDivision CentreofSustainableBuilding&ConstructionEnergyMarketAuthority BuildingandConstructionAuthority
foreword
2
33
Acknowledgements
Wewouldliketothankthefollowingorganisationsfortheirsupportandcontributionsinthedevelopmentofthishandbook:
1) GrenzonePteLtd
2) PhoenixSolarPteLtd
3) SingaporePolytechnic
4) SolarEnergyResearchInstituteofSingapore(SERIS)
5) SPPowerGrid
6) UrbanRedevelopmentAuthority
41Solar Photovoltaic (PV) Systems An Overview figure 1. the difference between solar thermal and solar PV systems
1.1 Introduction
Thesundeliversitsenergytousintwomainforms:heatandlight.Therearetwomaintypesofsolarpowersystems,namely,solarthermalsystemsthattrapheattowarmupwater,andsolarPVsystemsthatconvertsunlightdirectly intoelectricityasshowninFigure1.
When thePVmodules are exposed to sunlight, they generate direct current (DC)electricity.AninverterthenconvertstheDCintoalternatingcurrent(AC)electricity,sothatitcanfeedintooneofthebuildingsACdistributionboards(ACDB)withoutaffectingthequalityofpowersupply.
5Chapter 1SOlAR PhOtOVOltAIC (PV) SySteMS An OVeRVIew
figure 2. grid-connected solar PV system configuration
1.2 Types of Solar PV System
SolarPVsystemscanbeclassifiedbasedontheend-useapplicationofthetechnology.TherearetwomaintypesofsolarPVsystems:grid-connected(orgrid-tied)andoff-grid(orstandalone)solarPVsystems.
Grid-connectedsolarPVsystems
ThemainapplicationofsolarPV inSingapore isgrid-connected,asSingaporesmainislandiswellcoveredbythenationalpowergrid.MostsolarPVsystemsareinstalledonbuildingsormountedonthegroundiflandisnotaconstraint.Forbuildings,theyareeithermountedontherooforintegratedintothebuilding.ThelatterisalsoknownasBuildingIntegratedPhotovoltaics(BIPV).WithBIPV,thePVmoduleusuallydisplacesanotherbuildingcomponent,e.g.windowglassorroof/wallcladding,therebyservingadual purpose and offsetting some costs.
Theconfigurationofagrid-connectedsolarPVsystemisshowninFigure2.
Abuildinghastwoparallelpowersupplies,onefromthesolarPVsystemandtheotherfromthepowergrid.ThecombinedpowersupplyfeedsalltheloadsconnectedtothemainACDB.
TheratioofsolarPVsupplytopowergridsupplyvaries,dependingonthesizeofthesolarPVsystem.WheneverthesolarPVsupplyexceedsthebuildingsdemand,excesselectricitywill be exported into the grid.When there is no sunlight to generate PVelectricityatnight,thepowergridwillsupplyallofthebuildingsdemand.
6Chapter 1SOlAR PhOtOVOltAIC (PV) SySteMS An OVeRVIew
figure 3. Off-grid solar PV system configuration
Agrid-connectedsystemcanbeaneffectivewaytoreduceyourdependenceonutilitypower,increaserenewableenergyproduction,andimprovetheenvironment.
Off-gridsolarPVsystems
Off-gridsolarPVsystemsareapplicableforareaswithoutpowergrid.Currently,suchsolarPVsystemsareusuallyinstalledatisolatedsiteswherethepowergridisfaraway,suchasruralareasoroff-shoreislands.Buttheymayalsobeinstalledwithinthecityinsituationswhereitisinconvenientortoocostlytotapelectricityfromthepowergrid.Forexample,inSingapore,severalURAparkingsignlightsarepoweredbyoff-gridsolarPV systems.
Anoff-gridsolarPVsystemneedsdeepcyclerechargeablebatteriessuchaslead-acid,nickel-cadmium or lithium-ion batteries to store electricity for use under conditionswherethereislittleornooutputfromthesolarPVsystem,suchasduringthenight,asshowninFigure3below.
1.3 Solar PV Technology
This section gives a brief description of the solar PV technology and the commontechnical terms used.
AsolarPVsystemispoweredbymanycrystallineorthinfilmPVmodules.IndividualPV cells are interconnected to form a PV module. This takes the form of a panel for easy installation.
7Chapter 1SOlAR PhOtOVOltAIC (PV) SySteMS An OVeRVIew
Mono-Crystalline Silicon PV Cell Poly-Crystalline Silicon PV Cell
figure 5. PV technology family tree
PV Cell Types
Poly-crystalline
Mono-crystalline
Amorphous-Si (a-Si)
Tandema-Si/microcrystalline
CIGS(Copper Indium Gallium
Selenide)
CdTe(Cadmium Telluride)
Dye-sensitised (TiO2)
Commerciallyavailable product,
suitable for Singapore
R&D or pilot stage, orunsuitable for
Singapore
Special
Compound semiconductoreg GaAs-based
Crystalline Silicon(wafer based) Thin Film
PVcellsaremadeoflight-sensitivesemiconductormaterialsthatusephotonstodislodgeelectronstodriveanelectriccurrent.TherearetwobroadcategoriesoftechnologyusedforPVcells,namely,crystallinesilicon,asshown inFigure4whichaccounts for themajorityofPVcellproduction;andthinfilm,whichisnewerandgrowinginpopularity.ThefamilytreeinFigure5givesanoverviewofthesetechnologiesavailabletodayandFigure6illustratessomeofthesetechnologies.
figure 4. Mono-and Poly-Crystalline Silicon PV Cell
8Chapter 1SOlAR PhOtOVOltAIC (PV) SySteMS An OVeRVIew
CIgS thin filmMono-crystalline silicon
Poly-crystalline silicon
flexible amorphous thin film
figure 6. Common PV module technologies
CrystallineSiliconandThinFilmTechnologies
Crystallinecells aremade fromultra-puresilicon rawmaterial suchas thoseused insemiconductorchips.Theyusesiliconwafersthataretypically150-200microns(onefifthofamillimetre)thick.
Thin film is made by depositing layers of semiconductor material barely 0.3 to 2micrometres thick onto glass or stainless steel substrates. As the semiconductor layers aresothin,thecostsofrawmaterialaremuchlowerthanthecapitalequipmentandprocessing costs.
ConversionEfficiency
technology Module efficiency Mono-crystallineSilicon 12.5-15% Poly-crystallineSilicon 11-14% CopperIndiumGalliumSelenide(CIGS) 10-13% CadmiumTelluride(CdTe) 9-12% AmorphousSilicon(a-Si) 5-7%
table 1. Conversion efficiencies of various PV module technologies
Apart from aesthetic differences, the most obvious difference amongst PV celltechnologiesisinitsconversionefficiency,assummarisedinTable1.
Forexample,athinfilmamorphoussiliconPVarraywillneedclosetotwicethespaceofacrystallinesiliconPVarraybecause itsmoduleefficiency ishalved,forthesamenominalcapacityunderStandardTestConditions1(STC)rating.
1StandardTestConditionsrefertothefollowingtestingconditions:1,000W/m2 of sunlight250CcelltemperatureSpectrumatairmassof1.5
9Chapter 1SOlAR PhOtOVOltAIC (PV) SySteMS An OVeRVIew
ForcrystallinesiliconPVmodules,themoduleefficiencyislowercomparedtothesumofthecomponentcellefficiencyduetothepresenceofgapsbetweenthecellsandtheborderaroundthecircuit i.e.,wastedspacethatdoesnotgenerateanypowerhencelowertotalefficiency.
EffectsofTemperature
AnotherimportantdifferentiatorinsolarPVperformance,especiallyinhotclimates,isthetemperaturecoefficientofpower.PVcellperformancedeclinesascelltemperaturerises.
Forexample, inbright sunlight, cell temperatures inSingapore can reachover70C,whereasPVmodulesareratedatacelltemperatureof25C.Thelossinpoweroutputat70Cisthereforemeasuredas(70-25)xtemperaturecoefficient.
Mostthinfilmtechnologieshavealowernegativetemperaturecoefficientcomparedtocrystallinetechnologies.Inotherwords,theytendtoloselessoftheirratedcapacityastemperaturerises.Hence,underSingaporesclimaticcondition,thinfilmtechnologieswillgenerate5-10%moreelectricityperyear.
APVmoduledatasheetshouldspecifythetemperaturecoefficient.SeeTable2andchartinFigure7.
technology temperature Coefficient [%/C] Crystallinesilicon -0.4to-0.5 CIGS -0.32to-0.36 CdTe -0.25 a-Si -0.21
table 2. temperature coefficient of various PV cell technologes
mod
uleou
tputre
lativetoSTC
figure 7. the effects of a negative temperature coefficient of power on PV module performance
10
Chapter 1SOlAR PhOtOVOltAIC (PV) SySteMS An OVeRVIew
1.4 Technical Information
Single-core, double isolated sheathed cables that can withstand the environmentalconditions,andminimisetheriskofearthfaultsandshortcircuitsareusedtointerconnectthePVstringsandarrays.ThecableconnectionsareprotectedinenclosuresknownasjunctionboxthatprovidesthenecessaryconnectorsasshowninFigure10.
figure 8. PV String figure 9. PV Array
figure 10. Junction Box
ElectricityproducedbythesolarPVinstallationisintheformofDC.TheoutputofthePVinstallationisconnectedthroughtheDCmaincablestotheDCterminalsofthePVinverterwhereelectricityisconvertedfromDCintoAC.
After conversion, theAC current of thePV inverter is connected throughPV supplycabletothebuildingselectricalinstallation(ACdistributionboard).
Figure 11 shows a typical PV inverter connected to the electrical installation of abuilding.NotethattheactualconfigurationofthePVinvertermayvaryacrossdifferentsystems.
ThePVmodulesarenextconnectedinseriesintoaPVstringasshowninFigure8. APVarrayasshowninFigure9isformedbytheparallelaggregationofPVstrings.
11
Chapter 1SOlAR PhOtOVOltAIC (PV) SySteMS An OVeRVIew
Justlikeanyelectricalinstallationinabuilding,earthingisanimportantsafetyrequirementfor solar PV system. Arrangement must be made for proper connection of the solar PV system to the consumers electrical installation earthing system.
In locations susceptible to lightning strikes, a lightning protection system must beprovided,andalltheexposedmetallicstructuresofthesolarPVsystemmustbeboundto the lightning earthing system.
It is the responsibility of the consumers to have their solar PV systemsmaintainedregularly to ensure safe operation of their solar PV systems and electrical installations. SeeFigure12foradiagramshowingthesolarPVsystemformingpartofaconsumerselectrical installation.
figure 11. typical PV inverter connected to a buildings electrical installation
figure 12. Solar PV system forming part of a consumers electrical installation
dC Side AC Side
PVInverter
PV dC Main Cable
PV SupplyCable
AC distributionBoard
12
2Solar PV Systems on a Building2.1 Introduction
TherearemanyexamplesoverseaswherePVmodulesaremountedontheroofandintegratedintobuildingfaades.TheyworkparticularlywellinEuropeandNorthAmerica,assouth-facingfaadesintheseregionsarewellexposedtothesun.
InSingapore,wehavetoconsiderthatthesunpassesalmostdirectlyoverhead.ThisisbecausewearelocatedneartheEquator,andthepathofthesunfollowstheEquator,withseasonalvariationsofupto23.5o to the north or south. Therefore there are optimal positionstolocatethePVmodulesthathavetobetakenintoconsideration.RefertoAppendixAforexamplesofsolarPVsystemsonbuildingsinSingapore.
2.2 Installation Angle
To maximise electricity production for use in Singapore, the best location for thePVmodules tobe installed is righton topofabuilding, facing thesky.ThepossibleinstallationoptionsareshowninFigure13.
figure 13. where to install PV modules on a building in Singapore
13
figure 14. PV module frames trap dirt as water evaporates from aflat-mounted PV module
Vertical faades and steeply sloped roofs tend to suffer a big loss in the ability to generate electricityinexchangeforhigherpublicvisibility.
WiththePVmodulesfacingthesky,itispossibletoimprovetheyieldbyinstallingPVmoduleson trackers to follow thesun fromeast towestduring theday (single-axistrackers),andfromnorthtosouthduringseasonalchanges(dual-axistrackers).
However, trackerscanonly improvesystemperformanceunderdirectsunshine,andtheygivenoadvantageindiffusedsunlightconditions,suchasoncloudyorhazydays.
Thedownsideofhavingflat-mountedPVmodulesisthattheytendtogetdirtyfromrainwateranddust.SeeFigure14.ItisthereforebettertomountthePVmodulesatanincline(10-15oforframedmodules,oraslittleas3-5oforunframedmodules),toallowrainwatertoproperlydrainoff
2.3 Avoid Shading PV Modules
PV modules should be free from shade. Shading of any single cell of a crystalline silicon PVmodulewilldrasticallyreducetheoutputoftheentirePVmodule.
Thin filmPVmodules aremore tolerant to partial shading than crystalline siliconPVmodules.Typicalculpritsincludeshadowscastbytalltreesandneighbouringbuildings.
Chapter 2SOlAR PV SySteMS On A BuIldIng
14
Chapter 2SOlAR PV SySteMS On A BuIldIng
2.5 Solar PV Output Profile
SolarPVonlyproduceselectricitywhensunlightisavailable.TheoutputofasolarPVsystemvarieswithitsratedoutput,temperature,weatherconditions,andtimeoftheday.ThepoweroutputprofileofthePVinstallationasshowninFigure17,ataselectedtestsiteinSingaporecollectedoveraperiodfrom2002-2004,intermsofitscapacityfactor2,showsahighvariationofsolarPVoutput.
figure 15. BIPV modules integrated into a faade
figure 16. BIPV modules integrated into a skylight canopy
2.4 Aesthetic and Creative Approaches in Mounting PV Modules
Besides mounting PV modules on the rooftop, customised PV modules can beintegratedintothebuildingfaadeinacreative,aestheticallypleasingmanner.Theycanbemountedonanypartoftherooftoporexternalwallsthatiswellexposedtosunlighte.g.skylights,cladding,windows,andexternalshadingdevices.
Theycanalsobeintegratedintoexternalstructuressuchasfaadesandcanopies,asshowninFigure15andFigure16,respectively.
[2] PV Output capacity factor = Ratio of the actual output of the PV installation at time (t) over its output if it had operated at full rated output.
15
2.6 Solar PV Yield
The amount of electricity you are able to generate from a solar PV system depends not onlyontheavailabilityofsunshinebutalsoonthetechnologyyouchoosetoinstall.Forexample,atypical10-kWrooftopsolarPVsysteminSingaporewouldproduceabout11,000to12,500kWhannuallyusingcrystallinePVmodules,and12,000to14,500kWhannuallywithamorphoussiliconthinfilmPVmodules.
2.7 Cost of a Solar PV System
ThecostofyoursolarPVsystemwilldependonmanyfactors:systemconfiguration,equipmentoptions,labourcostandfinancingcost.Pricesalsovarydependingonfactorssuchaswhetherornotyourhomeisnew,andwhetherthePVmodulesareintegratedinto the rooformountedon the roof.Thecost alsodependson thesystemsizeorrating,andtheamountofelectricityitproduces.
Generally,solarPVsystemsentailhighcapitalcosts.Withsolarpower,youcansaveonthepurchaseofelectricityfromthegrid.Butevenwiththesesavings,itwilltakealongtimetorecoverthecapitalcostofthesolarPVinstallation.TheoperatingcostsforsolarPV installationsarenegligible,but theannualmaintenancecostbeyondthewarrantyperiodmayamountto0.5%to1%ofthecapitalcostoftheinstallation.
Thereforeonanoverallbasis,solarPV-derivedelectricityisstillmuchmoreexpensivethanthatfromthepowergrid.However,thecostofsolarPVhashistoricallybeenfallingbyabout4%ayear,andifthiscontinues,solarPVmaybecompetitivewithinthenext10years.ForincentivesonsolarPVsystem,pleaserefertoAppendixD.
figure 17. Varying daily power output profile of PV installation at a selected test site in Singapore
Chapter 2SOlAR PV SySteMS On A BuIldIng
PV
ou
tpu
t ca
pac
ity
fact
or
16
3Appointing a Solar PV System Contractor3.1 Introduction
YouwillneedtoselectacontractortoinstallyoursolarPVsystem.Ifinterested,youmaycheckwiththefollowingorganisationsforsomesolarPVsystemdesignersandcontractors:
TheListofSolarPVSystemcompanies inSingapore,available fromSustainableEnergyAssociationofSingapore,bycalling63388578orbyvisiting
http://www.seas.org.sg/about-seas/our-committees/cleanenergy/54
TheSingaporeSustainableDevelopment IndustryDirectory 2008/2009, availablefromtheSingaporeBusinessFederation,bycalling68276838orbyvisiting
http://www.sbf.org.sg/public/publications/industrydirectory.jsp
YourcontractorwillappointaLicensedElectricalWorker(LEW)whowillberesponsibleforthedesign,installation,testing,commissioning,andmaintenanceofyoursolarPVsystem.
Inthecaseofnon-residentialelectricalinstallationsthatrequireanelectricalinstallationlicence,theappointedLEWwhosupervisestheelectricalwork(DesignLEW)maynotbetheonewhotakeschargeofyourelectricalinstallation(InstallationLEW).TheDesignLEWwillthenhavetoworkwiththeInstallationLEWtoworkoutthetechnicalissues.
PleaserefertoAppendixBfordetailsonhowyoucanengageanLEWandthenecessaryconsultation process.
17
Chapter 3APPOIntIng A SOlAR PV SySteM COntRACtOR
3.2 Getting Started
First, compile a list of potential solar PV system contractors. Next, contact thecontractorstofindouttheproductsandservicestheyoffer.Thefollowingpointersmaygiveconsumersagoodsenseofthecontractorscapabilities:
Getanexperiencedandlicensedcontractor
Experienceininstallinggrid-connectedsolarPVsystemsisinvaluable,becausesomeelements of the installation process, particularly interconnection with the grid, areuniquetothesesystems.Acontractorwithyearsofexperiencewillalsodemonstrateanabilitytoworkwithconsumers,andpricetheirproductsandservicescompetitively.
ItisalsoimportanttogetacontractorwhoisanLEW.
Choosingbetweenbids
IfthereareseveralbidsfortheinstallationofasolarPVsystem(itisgenerallyagoodpractice to obtainmultiple bids), consumers should take steps to ensure that all ofthebidsreceivedaremadeonthesamebasis.ComparingabidforasolarPVsystemmounted on the ground against another bid for a rooftop system is like comparing apples to oranges.
Bids should clearly state themaximum generating capacity of the solar PV system[measured inwattspeak (Wp)or kilowattspeak (kWp)]. If possible, thebids shouldspecify thesystemcapacity inACwatts,orspecify theoutputof thesystemat theinverter.
Bids should also include the total cost of getting the solar PV systemcomponents,includinghardware,software,supportingstructure,meter,installation,connectiontothegrid(ifapplicable),permitting,goodsandservicestax,warranty,andfuturemaintenancecost(ifapplicable).
SolarPVsystemwarranty
AsolarPVsystemisaninvestmentthatshouldlastalongtime,typicallytwotothreedecadesforgrid-connectedapplications.TheindustrystandardforaPVmodulewarrantyis20-25yearsonthepoweroutput.
TherearetwomaincomponentstoaPVmodulewarranty:
Aworkmanshipwarrantythatofferstorepair,replaceorrefundthepurchasein case of defects. The period varies from one to as long as ten years,dependingonthemanufacturer.Twotofiveyearsistypical;and
18
AlimitedpoweroutputwarrantythatoffersavarietyofremediesincasethePVmodulesoutputunderSTCdropsbelowcertainlevel.Mostmanufacturerswarrantatleast90%oftheminimumratedoutputfor10years,and80%oftheminimumratedoutputfor20-25years.Takenotethattheminimumratedoutputisusuallydefinedas95%oftheratedoutputtoallowformanufacturingandmeasurementtolerances.SeeFigure18fordetails.
Chapter 3APPOIntIng A SOlAR PV SySteM COntRACtOR
Takenotethatunderthelimitedpowerwarranty,manufacturersseldomoffertoreplacethePVmoduleitself.Rather,attheirsolediscretion,theymayofferto:
RepairthedefectivePVmodules; SupplyenoughnewPVmodules to replace the lostpoweroutput in aPV
array.Forexample,ifyour20kWPVarrayonlyproduces16.1kWunderSTC,sixyearsafterinstallation,themanufacturermayopttosupplyyouwith1kWof PV modules to make up for the shortfall; or
Refundyouforthelostpoweroutput,afterdeductionaccordingtothenumber
ofyearsinuse.Fora25-yearwarranty,theannualdeductionisnormally4%.Forexample,ifyoufindthatyour20kWPVarrayonlyproduces16.1kWunderSTC,sixyearsafterinstallation,themanufacturermayopttoreimburseyourpurchasepriceminus24%(6yearsx4%).
Inallcases,themanufacturerdoesnotcoveryourcostsofdismounting,transporting,andreinstallingthePVmodules.Thewarrantyalsoexcludesproblemsresultingfromimproper installations; repairs, changes or dismounting by unqualified personnel;accidental breakage or abuse; lightning strikes and other acts of God.
figure 18. understanding a manufacturers limited power warranty
19
Chapter 3APPOIntIng A SOlAR PV SySteM COntRACtOR
Significantly,mostmanufacturersspecifythatthePVmoduleoutputwillbedeterminedbytheflashtestersintheirownpremises,ratherthanbyathirdparty.
The solar PV system contractor should assist in determiningwhether a PVmoduledefectiscoveredbywarranty,andshouldhandlethesituationwiththemanufacturer.
Regularmaintenance
Duringthedefectliabilityperiod(usuallyfor12monthsafterinstallation),solarPVsystemcontractors usually use remote monitoring data to prepare monthly performance reports of the installed solar PV system. They should come on site to rectify any problems flaggedbytheremotemonitoringservice.
Otherrelevantmatters
AnothermattertobeawareofisthatPVmodulemanufacturersareconstantlyupgradingtheirproducts,andadaptingnewsizesanddimensionstosuitmarket requirements.This means that you may no longer be able to buy an identical PV module to replace adefectiveoneinyourPVarrayafewyearsafterinstallation.NewerPVmodulesarelikelytobemoreefficientorhavedifferentphysicaldimensions,andmaynolongerfitexactlyintothegapleftbytheoldPVmodule.
Thisdoesnotmattermuchonalarge,ground-mountedsolarPVpowerplant,becausethenewmodulescanformanewrow.Butonabuilding-mountedsolarPVsystemitmayspoiltheaesthetics,andmaycauseproblemstotheelectricalconfiguration.
20
4Solar PV System Installation Requirements4.1 Electrical Installation Licence
An electrical installation refers to any electrical wiring, fitting or apparatus used fortheconveyanceandcontrolofelectricityinanypremises.AsolarPVsysteminstalledwithin suchpremises formspart of the consumers electrical installation and shouldcomplywiththerequirementsstipulatedintheElectricityAct(Cap.89A),theElectricity(ElectricalInstallations)RegulationsandtheSingaporeStandardCP5CodeofPracticeforElectricalInstallations.
Under the Electricity Act, the Energy Market Authority (EMA) licenses all non-residentialelectricalinstallations,withdemandexceeding45kilovoltampereorkVA.Forresidentialelectricalinstallationsandnon-residentialelectricalinstallationswithdemandbelowthethreshold45kVA,noelectricalinstallationlicenceisrequired.
ThelicencerequirestheowneroftheelectricalinstallationtoengageanLEWtotakechargeoftheelectricalinstallationandcomplywiththerelevantsafetystandardsandrequirements.YourappointedLEWshallconsultSPPowerGridLtdontheir technicalrequirementsandprocedures, ifyouwishtooperateyoursolarPVsysteminparallelwiththepowergrid.Theobjectiveistoensureallelectricalinstallations,includingsolarPVsystems,aresafetouse.
4.2 Electrical Safety Standards and Requirements
Agrid-connectedsolarPVsystemoperatesinparallelwiththepowergridsupply.Thepowergridsupplyisconsideredthesource,andtheelectricalinstallationwiththesolarPV system connected is considered as the load.
ThetechnicalrequirementforinstallationofasolarPVsystemisgiveninSection612oftheSingaporeStandardCP5.
ThereareinternationalproductstandardsonPVmodulesandelectricalcomponents.Forexample,PVmodulesshouldcomplywiththerequirementsofIEC61215forcrystallinesilicon terrestrial PVmodules or IEC 61646 for thin-film terrestrial PVmodules. Inaddition,PVarrayjunctionbox,PVgeneratorjunctionboxandswitchgearassembliesshouldcomplywiththerequirementsofIEC60439-1.
21
Chapter 4SOlAR PV SySteM InStAllAtIOn RequIReMentS
4.3 Application of Electrical Installation Licence
YourLEWwillbeabletoadviseyouwhetheryouneedtoapplytoEMAforanElectricalInstallation Licence for the use or operation of the electrical installation within thepremises of your building.
IfanElectricalInstallationLicenceisneeded,yourLEWwillsubmitthelicenceapplicationtoEMAonyourbehalf.IfyoualreadyhaveanElectricalInstallationLicenceissuedbyEMA,youneednotapplyforaseparatelicenceforthesolarPVsystemwithinthesamepremises.
The electrical licence fee payable to EMA is $100 per year (exclusive of goods andservicestax).
4.4 Conservation and Development Control Requirements
Atpresent, there isnospecific requirementorcontrolby theUrbanRedevelopmentAuthority (URA) on the use of installations such as a solar PV system.However,conservationprojects,orprojectswithintheCentralAreaaresubjecttoURAsUrbanDesignevaluationprocess.
Thestandarddevelopmentcontrolguidelinesapplytoprojectsthatmaynotbesubjectto conservation or urban design requirements, depending onwhich structure(s) thesolarPVsystemisinstalledonto.Forexample,ifasolarPVsystemisinstalledontherooftopofanattic,thentheatticguidelineswillapply.Likewise,ifasolarPVsystemisinstalledonraisedstructureslikeapavilion,thenthepavilionguidelineswillapply.
4.5 Guidelines on Conservation and Development Control
Architectsareadvisedtorefertotheconservationanddevelopmentcontrolguidelineswhen designing a development with a solar PV system installation. The respectiveguidelineisavailableatURAswebsite:
http://www.ura.gov.sg/conservation/Cons%20Guidelines.pdf http://www.ura.gov.sg/circulars/text/dchandbook.html
ShouldyouhavefurtherenquiriesonwhetheryourinstallationsconflictwiththeUrbanDesignorDevelopmentControlguidelines,youmaysubmityourenquiriestoURAeitherinpersonorthroughaQualifiedPerson(QP)aQPiseitheraregisteredarchitectoranengineerwiththeaccompanyingplansofthestructuresonwhichthesolarPVsystemwillbeinstalled:
Conservedbuildings Email:[email protected] Tel:63293355
Non-conservedbuildings Email:[email protected] Tel:62234811
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Chapter 4SOlAR PV SySteM InStAllAtIOn RequIReMentS
ShouldaformaldevelopmentapplicationtoURAberequired,itmustbemadeviaaQP.Thedetailscanbecheckedatthetwoweblinksbelow:
http://www.boa.gov.sg/register.html
http://www.peb.gov.sg/peb/process/searchPe
4.6 Structural Safety and Lightning Protection
Structural Safety
Toensuresafety,therearemeasuresandstepsthatneedtobetakenorconsideredwheninstallingasolarPVsystemontoaneworanexistingbuilding.Fornewbuildingdevelopments,thedesignofthestructuremusttakeintoconsiderationtheloadingofthesolarPVsysteminstallation,justlikeanyotherequipmentmountedontoabuildingstructure.
Forexistingbuildings,aprofessionalstructuralengineermayberequiredtocarryoutaninspectionoftheroofstructure,anddoacalculationonthestructuralloading.IftheroofisunabletowithstandtheloadingofthesolarPVsystem,structuralplanswillneedtobesubmittedtotheBuildingandConstructionAuthority(BCA)forapprovalbeforeabuildingpermitcanbeissuedforcommencementofinstallationworks.TheapplicationguidelineisavailableatthefollowingBCAswebsite:
http://www.bca.gov.sg/StructuralPlan/structural_plan_application.html
LightningProtection
Givenacertainlocation,solarPVsystemsareexposedtothethreatoflightningstrikes.As lightningcancausedamagetothePVmodulesand inverters,extracaremustbetakentoensurethatproperlightningprotectionisprovidedforthesolarPVsystemandthe entire structure. The inverters should be protected by appropriately rated surgearrestorsontheDCside.ItisgoodpracticetoalsoinstallsurgearrestorsontheACside.Structures and PV module frames must be properly grounded.
4.7 Connection to the Power Grid
If a solar PV system is designed tomeet only a fraction of the electricity load, thesystemwillneedtobeinterconnectedwiththepowergridtomeettheremainderoftheconsumers needs for electricity.
IfasolarPVsystemneedstobegrid-connected,interconnectioniskeytothesafetyofbothconsumersandelectricalworkers,andtotheprotectionofequipment.
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Chapter 4SOlAR PV SySteM InStAllAtIOn RequIReMentS
4.8 Get Connected to the Power Grid
IfyouintendtoconnectandoperateyoursolarPVsysteminparalleltothepowergrid,yourappointedLEWwillhave toconsultSPPowerGrid (SPPG)on theconnectionschemeandtechnicalrequirements.
The following documents set out the detailed consultation process and technical
requirements:
TheTransmissionCodeandtheMeteringCodearepublishedatEMAswebsite:
http://www.ema.gov.sg/media/files/codes_of_practice/electricity/transmission_code.pdf
http://www.ema.gov.sg/media/files/codes_of_practice/electricity/Metering_Code.pdf
SPPGs handbook, How to Apply for Electricity Connection, is published at SPPowerAssetswebsite:
http://www.sppowerassets.com.sg/PDF/howtoapply.pdf
4.9 Sale of Solar PV Electricity
Theexcesselectricitygeneratedfromagrid-connectedsolarPVcanbesoldbacktothepowergrid.ThearrangementsneededtoenablethissaleofsolarPVelectricityvary,dependingonwhetheryouareanon-residentialorresidentialuser.
Non-residentialUser
Ifyouareanon-residentialusergeneratingelectricitylessthan10MWfromthesolarPVsystemandwishtosellandgetpaidfortheelectricityyouinjectintothepowergrid,youwillberequiredtoapplyforaWholesaler (Generation)LicenceandregisterwiththeEnergyMarketCompany(EMC)toparticipateinthewholesaleelectricitymarket,whichiscalledtheNationalElectricityMarketofSingaporeorNEMS.
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Chapter 4InStAllIng A SOlAR PV SySteM
figure 19. flowchart for electricity licences for non-residential users
Theflowchart inFigure19describesthecircumstancesunderwhichtheWholesaler(Generation)Licenceisrequired.
GenerationLicenceorWholesaler(Generation)Licencenotrequired
ApplytoEMAforGenerationLicence
ApplytoEMAforWholesaler
(Generation)Licence
Proposed Solar PV System
GenerationCapacity10MW?
1MW GenerationCapacity