solar-cell-太阳能电池介绍.ppt

SolarCell Photovoltaics 20075418JuDae Hyun NonrenewableEnargy RenewableEnergy NonrenewableEnergy Renewable WhatisaSolarCell AstructurethatconvertssolarenergydirectlytoDCelectricenergy Itsuppliesavoltageandacurrenttoaresistiveload light battery motor Power CurrentxVoltage Current2xR Voltage2 RItislikeabatterybecauseitsuppliesDCpower Itisnotlikeabatterybecausethevoltagesuppliedbythecellchangeswithchangesintheresistanceoftheload BasicPhysicsofSolarCells Silicon Si isfromgroup4oftheperiodtable WhenmanySiatomsareincloseproximity theenergystatesformbandsofforbiddenenergystates Oneofthesebandsiscalledthebandgap Eg andtheabsorptionoflightinSiisastrongfunctionofEg TheSundailyprovidesabout10000timesmoreenergytotheEarththanweconsumePhotovoltaictechnologydirectlyconvertssolarenergyintoelectricityNomovingparts nonoise noemissions longlifetimeLargeindustrialpotential costreductionsneededFeedstockforPVindustryissilicon thesecondmostabundantelementinthecrustoftheEarth TheSunasEnergySource SolarEnergystatus MarketisexplodingThesolarindustryisveryprofitableLackofhighlypurifiedsilicon polysilicon Costofsolarelectricityistoohigh R Dfocusonreducingcostandincreasingefficiency ActualGrowthvs HistoricForecasts SolarEnergystatus MarketisexplodingThesolarindustryisveryprofitableLackofhighlypurifiedsilicon polysilicon Costofsolarelectricityistoohigh R Dfocusonreducingcostandincreasingefficiency Grossrevenuedevelopment SolarEnergystatus MarketisexplodingThesolarindustryisveryprofitableLackofhighlypurifiedsilicon polysilicon Costofsolarelectricityistoohigh R Dfocusonreducingcostandincreasingefficiency SolarGradeSiliconSupply Demand MT year SolarEnergystatus MarketisexplodingThesolarindustryisveryprofitableLackofhighlypurifiedsilicon polysilicon Costofsolarelectricityistoohigh R Dfocusonreducingcostandincreasingefficiency Costreductions existingtechnologies Thinnerwafers Wiresawing LasercuttingandetchingHigherefficiencies Semiconductortechnologiesonsinglecrystalwafers examplesSanyo SunPower Thinfilmtechnologies flatpaneldisplay Publicincentivesareimportant Costgoalsforthirdgenerationsolarcells Efficiencyandcostprojectionsforfirst second andthirdgenerationphotovoltaictechnology wafers thin films andadvancedthin films respectively Source UniversityofNewSouthWales Nextgenerationtechnology SiliconnanostructuresBandgapengineeringofsilicon Applicationscouldbetandemsolarcellsandenergyselectivecontactsforhotcarriersolarcells Fabricationofsiliconnanostructuresconsistingofquantumwellandquantumdotsuperlatticestoachievebandgapcontrol Up DownconvertersLuminescentmaterialsthat EITHERabsorbonehighenergyphotonandemitmorethanonelowenergyphotonjustabovethebadgapofthesolarcell down conversion ORthatabsorbmorethanonelowenergyphotonbelowthebandgapofthecellandemitonephotonjustabovethebandgap up conversion Nextgenerationtechnology cont Understandingcellefficiency HotcarrierCellsThisconcepttacklesthemajorPVlossmechanismofthermalisationofcarriers Thepurposeistoslowdowntherateofphotoexcitedcarriercoolingcausedbyphononinteractioninthelatticetoallowtimeforthecarrierstobecollectedwhilsttheyarestillhot andhenceincreasingthevoltageofacell Nextgenerationtechnology cont ThermoelectricsolarcellsApplicationoftheconceptofenergy selectiveelectrontransportusedinhotcarriersolarcells todevelopthermoelectricsandthermo ionicsdevices Nextgenerationtechnology cont ThePVValueChain multi crystalline Pricesareactuallyincreasing Howdoessolarenergywork SolarElectricorPhotovoltaicSystemsconvertsomeoftheenergyinsunlightdirectlyintoelectricity Photovoltaic PV cellsaremadeprimarilyofsilicon thesecondmostabundantelementintheearth scrust andthesamesemiconductormaterialusedforcomputers Whenthesiliconiscombinedwithoneormoreothermaterials itexhibitsuniqueelectricalpropertiesinthepresenceofsunlight Electronsareexcitedbythelightandmovethroughthesilicon Thisisknownasthephotovoltaiceffectandresultsindirectcurrent DC electricity PVmoduleshavenomovingparts arevirtuallymaintenance free andhaveaworkinglifeof20 30years SiliconSolarcell Photovoltaics MostcurrentsolarcellsarephotovoltaicTypicallymadefromsiliconoramorphoussilicon Typicalefficiency 12 Bestefficiencyeverinlaboratory 30 Theoreticalmaximum includingconcentratinglight 43 Genericdesign dopedpnjunction Photonscomeinandphotoionizedonors Built inelectricfieldatjunctioncausescarrierstoflow buildingupapotential voltage btwthepandnsides Clearlyonecanplaywithdifferentbandgapsystemstoarriveatmaterialswithdifferentabsorptionspectra Also goodmobilityofchargeessentialforthistoworkwell trappingofchargeorpoormobilitywillkillefficiency Principlep nJunctionDiode SiliconSolarcell Ref SoftCondensedMatterphysicsgroupinuniv ofQueenland Siingot 330 m 2cmx2cmSurfacecleaning Texturing chemicalv groove p njunction POCl3 900 C ITOincreasingminortycarriercorrection ARC Poly SiSolarcellMakingprocess BackSurfaceFieldDepositionAlandAgohmic contact ForwardsurfaceElectrode Anti reflectioncoating ARC TiO2deposition H2diffusiondanglingbondH2bonding Decreasingrecombination Measure AnindividualPVcelltypicallyproducesbetween1and2watts SolarCell Module Array decreasetheareaofsolarcellmaterialbeingusedinasystem Concentratorcollectors Flat platecollectorstypicallyuselargenumbersorareasofcellsthataremountedonarigid flatsurface substrate metal glass plastic Theyaresimplertodesignandfabricate Theydonotrequirespecialoptics speciallydesignedcells ormountingstructuresthatmusttrackthesunprecisely plus flat platecollectorscanuseallthesunlight Flat PlateSystems UsesforSolarEnergy SolarHomeSystems Space WaterPumping Telecom MainApplicationAreas Off gri