光伏材料基本原理

1.SolarPhotovoltaicTheory1-1.BasicprinciplesofPV11-1.BasicprincipleofPV1-1.BasicprinciplesofPV

1-1-1.Mechanismofgeneration

1-1-2.VarioustypeofPVcell

1-1-3.Installationexample

1-1-4.Basiccharacteristic

1-1-5.CasesturdyContents2++++----PhotoVoltaiccellElectrodeP-TypeSemiconductorN-TypeSemiconductorReflect-ProofFilmElectrodeSolarEnergyLoadElectricCurrent1-1-1.MechanismofgenerationMechanismofgenerationThesolarcelliscomposedofaP-typesemiconductorandanN-typesemiconductor.Solarlighthittingthecellproducestwotypesofelectrons,negativelyandpositivelychargedelectronsinthesemiconductors.Negativelycharged(-)electronsgatheraroundtheN-typesemiconductorwhilepositivelycharged(+)electronsgatheraroundtheP-typesemiconductor.Whenyouconnectloadssuchasalightbulb,electriccurrentflowsbetweenthetwoelectrodes.31-1-1.MechanismofgenerationDirectionofcurrentinsidePVcellPNCurrentappears

tobeinthe

reversedirection?InsidecurrentofPVcelllookslike“Reversedirection.”Why??BySolarEnergy,currentispumpedupfromN-poletoP-pole.Ingeneration,currentappearsreverse.Itisthesameasforbattery.PNLookslike

reverse41-1-1.MechanismofgenerationVoltageandCurrentofPVcell(I-VCurve)(V)(A)Voltage(V)Current(I)PNAShortCircuitOpenCircuitPNVabout0.5V(Silicon)HighinsolationVoltageonnormaloperationpoint

0.5V(incaseofSiliconPV)Currentdependon

-Intensity

ofinsolation

-SizeofcellLowinsolationNormaloperationpoint

(MaximumPowerpoint)IxV=W51-1-1.MechanismofgenerationTypicalI-VCurve(V)(A)Voltage(V)Current(I)0.49VStandardinsolation1.0kWh/m20.62V4.95A5.55ADependon

typeofcellorcell-material

(Si=0.5V)Dependoncell-sizeDependon

Solarinsolation6CrystallineNon-crystallineSinglecrystalPolycrystallineAmorphousGalliumArsenide(GaAs)ConversionEfficiencyofModule10-17%10-13%7-10%18-30%ConversionEfficiency=ElectricEnergyOutputEnergyofInsolationoncellx100%Dye-sensitizedTypeOrganicThinLayerType7-8%2-3%1-1-2.VarioustypeofPVcellTypesandConversionEfficiencyofSolarCellSiliconSemiconductorCompoundSemiconductorSolarCellOrganicSemiconductor7Crystalcell(SinglecrystalandPolycrystallineSilicon)SinglecrystalPolycrystalline1-1-2.VarioustypeofPVcellFormedbymeltinghighpuritysiliconlikeasIntegratedCircuitFormassproduction,cellisslicedfromroughlycrystallizedingot.8SurfaceofPVcell1-1-2.VarioustypeofPVcellFrontSurface

(N-Typeside)AluminumElectrode

(Silvercoloredwire)Toavoidshading,electrodeisveryfine.Antireflectionfilm

(Bluecoloredfilm)BacksurfaceisP-type.Allbacksurfaceisaluminumelectrodewithfullreflection.ExampleofPolyCrystallinePV9SinglecrystalPolycrystalline120W(25.7V,4.7A)1200mm800mm800mm1200mm1-1-2.VarioustypeofPVcellPVModule(Singlecrystal,PolycrystallineSilicon)(3.93ft)（2.62ft）（3.93ft）(2.62ft)128W(26.5V,

4.8A)EfficiencyishigherEfficiencyislowerSamesize101-1-2.VarioustypeofPVcellHierarchyofPV2–3W100-200W10-50kWCellArrayModule,Panel

Volt Ampere Watt SizeCell 0.5V 5-6A 2-3W about10cmModule 20-30V 5-6A 100-200W about1mArray 200-300V 50A-200A 10-50kW about30m6x9=54(cells)100-300(modules)111-1-2.VarioustypeofPVcellRoughlysizeofPVPowerStation.HowmuchPVcanweinstallinthisconferenceroom?1kwPVneed10m2Pleaseremember10m(33feet)20m(66feet)Conference

Room

(Wearenow)Ourroomhasabout200m2Wecaninstallabout20kWPVinthisroom(108feet2)(2,178feet2)121-1-3.InstallationexampleRooftopofresidence(Gridconnected)MostpopularinstallationstyleinJapan.

(Almost85%PVinJapan)Ownercansellexcesspowertopowerutility.131-1-3.InstallationexampleRooftopofschool,community-centerbuilding.

(Foreducationandemergencypower)141-1-3.InstallationexampleDistantandindependentpowersupply(Offgrid)RelaystationontopofmountainAdvertisingsignbesidehighway151-1-3.InstallationexampleMountainlodge(Offgrid)1.2kWsystemInverterandcontroller161-1-3.InstallationexampleStationarypowerstation(Gridconnected)Site: FunafutiTuvaluInstallation: Feb.in2008Capacity: 40kWPurpose: Gridconnectedpowersupplyforfuelconservation

andCO2reduction.e8&PPAprojectinTuvalu30kWarray10kWarray171-1-3.InstallationexampleStationarypowerstation(Offgridorminigrid)Solarcellcapacity:3.4kWWindPowercapacity:1.8kWInvertercapacity:5kVASite: MongoliaInstallation: May&Junein1999Purpose:Forlighting,refrigerator

andoutletinahospital.181-1-3.InstallationexampleSolarHomeSystem(SHS)SolararraySolararraySolararraySolararray

Controller

Light

Storagebattery191-1-4.BasicCharacteristicI/VcurveandP-MaxcontrolPNAVToobtainmaximumpower,currentcontrol(orvoltagecontrol)isveryimportant.(V)(A)Voltage(V)Current(I)IxV=WP2PMAXP1VpmaxIpmaxI/VcurveP-Maxcontrol“Powerconditioner”(mentionedlater)willadjuststobemostsuitablevoltageandcurrentautomatically.Powercurve201-1-4.BasicCharacteristic

EstimateobtainedpowerbyI/Vcurve(V)(A)Voltage(V)Current(I)12108642000.10.20.30.40.50.6PNAPVcharacter

(I/Vcurve)Iftheloadhas0.05ohmresistance,

crosspointofresistancecharacterand

PV-Characterwillbefollowingpoint.Thenpoweris10x0.5=5WResistancecharacterOhm’stheory211-1-4.BasicCharacteristicI/Vcurvevs.InsolationintensityPNPNMismatch5A1APNPNBypass

Diode5A1A4A(V)(A)Current(I)HighintensityinsolationLowintensityinsolationIxV=W5A1ACurrentisaffectedlargelybychangeofinsolationintensity.Partiallyshadedserialcellwillproducecurrentmismatch.BypassDiode221-1-4.BasicCharacteristicTemperatureandefficiencyModuleTemperature(deg.C)Efficiency(%)CrystallinecellAmorphouscell0.25(%/deg)Typical

(25C)Sum