PV_system_Util_Scale_BIPV

ELEG628Gridconnectedsystems20081PVSystems:Standalone(SA)vsGridConnected(GC)•Verydifferentdesignphilosophy•SA:availabilitykeyissue–Verycomplicatedanalysis,design,operation(interactions)–Worstcase,longestcloudyperiod–Reliability(PV,dieselgen,storage)vs$–LossofLoadProbability(LLP)•LLP(%)=100-(%availability)–Keyparameter:Amp-hours@VBAT–Hybrid(diesel)forlargerloads,hireliability•GC:annualordailypeakpower–Totalannualoroffsetpeakpower–Keyparameter:annualkW-hours–LLPnoconcern,gridisbackup,nopowerifgriddownELEG628Gridconnectedsystems200822Standalone(SA)PVSystemswithbatteryELEG628Gridconnectedsystems200832Gridconnected(GC)PVSystemsPowerCond=inverter,MPT,displayELEG628Gridconnectedsystems20084Components(BOS)red=gridconnected•Chargecontroller(CC);“regulator”–Charge/dischargebattery;regulatesVBAT–Protectover-charge/discharge–MayhaveMPPT(MaxPowerTracker,electronicpsuedoload)•Inverter(dc⇒ac)–Modifiedsquarewave(limitedappliances)orsine–Efficiency85-95%–MayhaveMPTand/orCC–GCorSAverydifferent:synchedtogridvsself-generatingac•Batteries(efficiency=80-90%)•Dieselgenerator•Fuses,mountingrails,posts,wiring,groundrod,disconnects,smartsystemmonitor•NB:MPPTTrackingiselectronic,1-2axistrackingismechanical,theyaretotallydifferentconcepts,sameterm,samegoal(maxPVoutput)ELEG628Gridconnectedsystems20085Gridconnectedsizingandgoals•Verydifferentfromstandalone;gridisback-up•EithermaxPVyoucanaffordormaxyoucanfitonroof•Premiumonefficiency;maxoutputperarea;notThinFilm•Partialoffsethouseload,typicallynotnetPVenergy•Netmetering:utilitybuysbackatsamepriceuptoload–Rarelysendyoucheckifnetpositiveenergy(PVload)•FixedtiltPVarray,inverter(MPT),fuses,dc+acswitch–Datadisplay/datalog,secondspinningmeter•Aesthetics(color,formfactor,stand-off)•HigherTsincelesscirculation(stand-off)•Fewsystemsw/batterytostoreexcess,backupselectloads–Improvereliability,security,gridtocharge/equalizebattery–Increasecost,complexity,either2inverters(SA+GC)orfewcomboELEG628Gridconnectedsystems20086Underfederallaw,utilitiesmustallowindependentpowerproducerstobeinterconnectedwiththeutilitygrid,andutilitiesmustpurchaseanyexcesselectricitytheygenerate.-U.SDepartmentofEnergyELEG628Gridconnectedsystems20087ResidentialPVprojectGardnerMA(mid1990s)2kWgridconnectedtostudyPV-utilityinteractionELEG628Gridconnectedsystems200883kWPVperapartment(Netherlands)ELEG628Gridconnectedsystems20089Trackthesun:1and2axisflatplateandconcentrator(APS)ELEG628Gridconnectedsystems200810Gridconnectionissues(10kW)•Inverter/interconnection–Typically240VACoutputtointerfacewithresidentialgridinput–Codes:IEEE929-2000,NECArt.690–Powerquality,“islanding”,grounding–Linevoltage:88%VAC110%elseinvertershutdown2sec–Freq:59.3f60.5Hz,nodc–Off5minafterdisturbance–NegligibleEMinterference–Componentground,GFI,disconnects•Metering:whereisPVconnected–Util.side:nodirectbenefittocustomer,(utilityownsPV)–Cust.side:complicated(offsetload);differentfinancialarrangements–Answer:netmetering(35states);notallmetersallow2-wayELEG628Gridconnectedsystems200811Gridconnectionissues(10kW)•Netmetering:billingagreement•Interconnection:techandlegalissues–ULapprovedcomponents,noinspectn10kW–Utilitycanreqinsurance,inspectconditionalperiod,manybarriers–Candenypowerexporttogridexceedingsomelimit(100kW)•Customerside:–Rebate($/kW),netmeteroffsetkW-hrcharges,25-50%common–Tariff:Utilpayhigher$/kWhr(Germany20yr;NJ,CAnew)–Encouragescustomertomaintaininterest,output,qualityassurance–verifyacperformance;datalog/display;bothloadandPV–AccumulategreenRECs;bundlewithotherusers;selltoutil/corpSteveHegedus,InstituteofEnergyConversion,UofDFebruary21,2007Engrw/oBordersslide#12Inverter-to-PV:sizingfactorCommontoundersizeinverterSF=PINV/PPV‰Inverters$800/kW,muchcheaperthanPV,sonotcostPVDCpowerrarelyoperatesatrated(PR=0.8-0.9)ButsometimesPVexceedsinverterratingInverterthermalprotectionavoiddamageSF=70-150%allowinverterlimitlosses1%manylocationsLimitedchoiceofinvertersizes;costeffectiveforSF1SteveHegedus,InstituteofEnergyConversion,UofDFebruary21,2007Engrw/oBordersslide#13Inverter-to-PV:sizingfactor,measvscalcTopL:am(squares)pm(triangle)TopR:VdcforSF=55%BotR:VdcforSF=100%??????SteveHegedus,InstituteofEnergyConversion,UofDFebruary21,2007Engrw/oBordersslide#14EffectofoversizingPVMPPTincreasesV,moveoutonI-Vcurve,limitP=constantDecreasePevenmoretoprotectinverterfromoverheatingELEG628Gridconnectedsystems200815LargescalePVsystems(500kW)•Fewin80-90’s:demonstration,learningexperience•Unrealisticcosts–Lower:Subsidizedbyutility/govt–Higher:dataacq,workerfacilities,testingnewhardware,intentionalvariations•Peakshavingordistributedgeneration•Fixedtilt,1or2axistracking•Lessonslearned(PVUSA)–PV:verylowfailurerate(0.1%)–Inverter(PCU):highfailurerate(butthiswas2000)–Minimizeon-siteassemblyELEG628Gridconnectedsystems200816UtilityPVPerformanceEvaluation•Threeparameterstocharacterizeperformance–SeearticlesbyMarionetalorMooreetal•ReferenceYield=solarresourcefortilt,location–YR=planeofarray(POA)irradiance/(1kW/m2)inkWhrs/kW–IndependentofPVsize,temperature,dirtetc•FinalYield=#