太阳能路灯控制系统外文资料文档格式.doc

太阳能路灯控制系统外文资料文档格式.doc

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中英文资料

学生姓名：

张建木

专业：

电子信息工程

班级：

D0745

学号：

11号

论文起止日期：

2011年4月至6月

英文原文：

PHOTOVOLTAICPOWERGENERATION

ABSTRACT

Thisreportisanoverviewofphotovoltaicpowergeneration.ThepurposeofthereportistoprovidethereaderwithageneralunderstandingofphotovoltaicpowergenerationandhowPVtechnologycanbepracticallyapplied.

Thereisabriefdiscussionofearlyresearchandadescriptionofhowphotovoltaiccellsconvertsunlighttoelectricity.Thereportcoversconcentratingcollectors,flat-platecollectors,thin-filmtechnology,andbuilding-integratedsystems.Thediscussionofphotovoltaiccelltypesincludessingle-crystal,poly-crystalline,andthin-filmmaterials.Thereportcoversprogressinimprovingcellefficiencies,reducingmanufacturingcost,andfindingeconomicapplicationsofphotovoltaictechnology.Listsofmajormanufacturersandorganizationsareincluded,alongwithadiscussionofmarkettrendsandprojections.

Theconclusionisthatphotovoltaicpowergenerationisstillmorecostlythanconventionalsystemsingeneral.However,largevariationsincostofconventionalelectricalpower,andotherfactors,suchascostofdistribution,createsituationsinwhichtheuseofPVpoweriseconomicallysound.PVpowerisusedinremoteapplicationssuchascommunications,homesandvillagesindevelopingcountries,waterpumping,camping,andboating.Grid-connectedapplicationssuchaselectricutilitygeneratingfacilitiesandresidentialrooftopinstallationsmakeupasmallerbutmorerapidlyexpandingsegmentofPVuse.Furthermore,astechnologicaladvancesnarrowthecostgap,moreapplicationsarebecomingeconomicallyfeasibleatanacceleratingrate.

INTRODUCTION

ThisreportistheresultofGaleGreenleaf’sOctober19,1998requestforproposal.BillLoukandTomPenickrespondedtoherrequestwithaproposal,datedOctober30,1998,tocontinueearlierresearchonphotovoltaicpowergeneration.TheproposalwasapprovedandresultedincontinuedresearchfollowedbyapresentationonNovember30,1998andthisfinalreportonphotovoltaicpowergeneration.

PHOTOVOLTAICTECHNOLOGY

Scientistshaveknownofthephotovoltaiceffectformorethan150years.Photovoltaicpowergenerationwasnotconsideredpracticaluntilthearrivalofthespaceprogram.Earlysatellitesneededasourceofelectricalpowerandanysolutionwasexpensive.Thedevelopmentofsolarcellsforthispurposeledtotheireventualuseinotherapplications.

DISCOVERYANDDEVELOPMENTOFPHOTOVOLTAICPOWER

Thephotovoltaiceffecthasbeenknownsince1839,butcellefficienciesremainedaround1%untilthe1950swhenU.S.researcherswereessentiallygivenablankchecktodevelopameansofgeneratingelectricityonboardspacevehicles.BellLaboratoriesquicklyachieved11%efficiency,andin1958,theVanguardsatelliteemployedthefirstpracticalphotovoltaicgeneratorproducingamodestonewatt.

Inthe1960s,thespaceprogramcontinuedtodemandimprovedphotovoltaicpowergenerationtechnology.Scientistsneededtogetasmuchelectricalpoweraspossiblefromphotovoltaiccollectors,andcostwasofsecondaryimportance.Withoutthistremendousdevelopmenteffort,photovoltaicpowerwouldbeoflittleusetoday.

POWEROUTPUTANDEFFICIENCYRATINGS

Thefiguresgivenforpoweroutputandefficiencyofphotovoltaiccells,modules,andsystemscanbemisleading.Itisimportanttounderstandwhatthesefiguresmeanandhowtheyrelatetothepoweravailablefrominstalledphotovoltaicgeneratingsystems.

PowerRatings

Photovoltaicpowergenerationsystemsareratedinpeakkilowatts（kWp）.Thisistheamountofelectricalpowerthatanew,cleansystemisexpectedtodeliverwhenthesunisdirectlyoverheadonaclearday.Wecansafelyassumethattheactualoutputwillneverquitereachthisvalue.Systemoutputwillbecompromisedbytheangleofthesun,atmosphericconditions,dustonthecollectors,anddeteriorationofthecomponents.Whencomparingphotovoltaicsystemstoconventionalpowergenerationsystems,oneshouldbearinmindthatthePVsystemsareonlyproductiveduringthedaytime.Therefore,a100kWphotovoltaicsystemcanproduceonlyafractionofthedailyoutputofaconventional100kWgenerator.

EfficiencyRatings

Theefficiencyofaphotovoltaicsystemisthepercentageofsunlightenergyconvertedtoelectricalenergy.Theefficiencyfiguresmostoftenreportedarelaboratoryresultsusingsmallcells.Asmallcellhasalowerinternalresistanceandwillyieldahigherefficiencythanthelargercellsusedinpracticalapplications.Additionally,photovoltaicmodulesaremadeupofnumerouscellsconnectedinseriestodeliverausablevoltage.Duetotheinternalresistanceofeachcell,thetotalresistanceincreasesandtheefficiencydropstoabout70%of