Operation And Maintenance Of Solar Electric Systems

I nt r oduct i ont oSol arPower Al mostev er yaspectofmoder nl i f ei sdependentonel ect r i ci t y .Ast echnol ogy i mpr ov es,al mostev er y t hi ngweuse,f r om cooki ngandcl eani ngappl i ancest ospor t s andent er t ai nmentequi pment , hasbeenupdat edt oi ncl udeel ect r oni cci r cui t r y .Howev er , soci et y ’ sdependenceonel ect r i ci t yi si ncr easi ngl ypr obl emat i c: asconv ent i onalf ossi l f uelr eser v esdi mi ni shandt hedangerofcl i mat echangemat er i al i zes,t heneedf or al t er nat i v eener gysour cesi si ncr eased.Sol arpower ,t hati sel ect r i ci t ygener at edusi ng ener gyf r om t hesun,i sanat t r act i v ewayt oof f setourr el i anceonel ect r i ci t ygener at ed bybur ni ngf ossi l f uel s.

Thebeaut yofsol arpoweri st hati thasv er yf ew r unni ngcost s:oncet hecapi t al i nv est menthasbeenmadet heener gyi sef f ect i v el yf r ee,whi l ef ossi lf uel smustbe pur chasedcont i nuousl yandal l i ndi cat i onsar et hatpr i ceswi l l cont i nuet or i se. Renewabl eener gyt echnol ogi est hatmakeuseofwi ndandsol arpowerwi l lt her ef or e pl ayani mpor t antr ol ei nr educi nggl obalGHGemi ssi onsandar el i kel yt or epr esenta l ar gepor t i onoft hewor l d’ sener gypr oduct i oni nt hef ut ur e. Sol arel ect r i csy st em Sol arener gyi shar nessedbyusi ngsol arel ect r i csy st ems,al soknownasphot ov ol t ai c ( PV)sy st ems.Thewor dphot ov ol t ai ci sder i v edf r om t heLat i nwor dsphot o( l i ght )and

v ol t ai c( ener gy ) .Sol arel ect r i c and sol art her malsy st ems ar ev er y di f f er enti n appear anceandoper at i on. Of f gr i dsy st ems Anof f gr i dorst andal onesol arel ect r i csy st em i sdesi gnedt or epl aceorsuppl ement conv ent i onal mai nspowersuppl y .Theyar emostcommonl yusedi nr ur al or r emot ear easwher emai nspoweri snotav ai l abl eduet ot hehi ghcostofgr i dext ensi on.

Of f gr i dsy st emsusesol arpowert ochar gebat t er i est hatst or et hepowerunt i li ti s neededf oruse.Thebat t er ypoweri st henusedt ooper at eappl i ances( e. g.l i ght i ng, pumps,r ef r i ger at i onet c. )ei t herdi r ect l yf r om t hebat t er i esasl owv ol t ageequi pment ( e. g.12VDCl i ght s)orf r om apoweri nv er t er ,whi chi sconnect edt ot hebat t er i esand conv er t st hebat t er yv ol t aget omai nsequi v al entf orusei nr egul arACequi pment( e. g. comput er , t el ev i si on, r adi oet c. ) .

Fi gur e1. 4Lay outofanof f gr i dsy st em

Fi ger1. 5Smal l of f gr i dsol arel ect r i csy st emsar eof t ent hemostconv eni entand cost ef f ect i v eopt i onf ort hosel i v i ngi nr ur al ar easoft hedev el opi ngwor l dsuchast he WestSahar a, wher et hi ssy st em i sl ocat ed Gr i dconnect edsy st ems Gr i dconnect edsy st emsar enor mal l yf oundi nur banar east hathav er eadi l y av ai l abl emai nssuppl yandi nst eadofst or i ngt heel ect r i ci t ygener at edbyt hePVsy st em i nbat t er i es,t hepoweri sf edbacki nt ot hegr i d.I nt hi swayt hegr i dact sasaki ndof st or agemedi um andwhenpoweri sneededi nt hebui l di ngi tcanbei mpor t edf r om t he gr i d.Oneoft hekeybenef i t soft hi si st hatt hesy st em doesnothav et osuppl yenough el ect r i ci t yt ocov ert hepr oper t y ’ spowerdemandasi nanof f gr i dsy st em.Thepr oper t y canbepower edbyt hePVsy st em,t heel ect r i ci t ygr i doracombi nat i onoft het wo, meani ngt hatt hesy st em canbeassmal lorl ar geast heownerdesi r es.Excesspower gener at edbyt hePVsy st em wi l l beexpor t edt ot hepowergr i dandi nmanyar east he sy st em owneri spai df ort heexpor t edpower .

Themaj orcomponent sofagr i dconnect edPV sy st em i ncl udet hePV ar r ay , i nv er t erandt hemet er i ngsy st em.I naddi t i ont ot hesemaj orcomponent sar et he

necessar ycabl es,combi nerboxes,pr ot ect i ondev i ces,swi t ches,l i ght ni ngpr ot ect i on andsi gnage.

Fi gur e1. 8Ty pi cal smal l gr i dconnect edPVsy st em

Di st r i but edgr i dconnect edPVsy st ems Ther ear et y pi cal l yt wot y pesofsy st em: commer ci al andr esi dent i al . Commer ci alsy st emsar e gener al l ygr eat ert han 10kWp and ar el ocat ed on bui l di ngssuchasf act or i es, commer ci al busi nesses, of f i cebl ocksandshoppi ngcent r es. Thepowergener at edbyt hesesy st emsi st y pi cal l yconsumedbyt hel oadswi t hi nt he bui l di ng, sonoexcesspoweri sexpor t edt ot heel ect r i ci t ygr i d. Resi dent i alsy st emsr ef ert ot hosei nst al l edonhomesandar egener al l ysmal l er t hancommer ci alsy st ems,t y pi cal l ybet ween1and5kWp.Thepowergener at edby t hesesy st emsi sf i r stconsumedbyanyl oadsoper at i ngi nt hehousedur i ngt heday ;

excesspoweri sf edi nt ot hegr i dpr ov i di ngel ect r i ci t yt onear bybui l di ngs.

Modul e1( Chapt er1) Sol arResour ceandRadi at i on Sol arr esour ces

Thesuni st hesour ceofal mostal lener gyonourpl anet ,ei t herdi r ect l yas sunl i ghtori ndi r ect l yaswi ndandwav es.Ev ent hecoalr eser v eswemi net odaywer e oncel i v i ngpl ant st hatgai nedt hei rener gyf r om phot osy nt hesi s:t hepr ocessbywhi ch sunl i ght , car bondi oxi deandwat erar econv er t edt ocar bohy dr at es.Thesun’ sseemi ngl y endl essener gysuppl yi sdr i v enbyapr ocessknownasnucl earf usi on,wher eat omsof hy dr ogencombi net of or m anat om ofhel i um r el easi ngal ar geamountofener gyi nt he pr ocess.Thehel i um at om mayt hencombi newi t hot herhel i um orhy dr ogenat omst o r el easeev enmor eener gy .Theener gypr oducedi nt hehear toft hesuni semi t t edas el ect r omagnet i cr adi at i on.El ect r omagnet i cr adi at i oni semi t t edi nmanyusef ulf or ms i ncl udi ng mi cr owav es ( as used i n mi cr owav e cooki ng) ,r adi o wav es ( used i n t el ecommuni cat i ons)and v i si bl el i ght .Sol arcel ldesi gner sf ocusoncapt ur i ng t he ener gycar r i edi nv i si bl el i ght . Whi t ev i si bl el i ghtcanbedi v i dedi nt omanycol our s;eachr ayofcol ourhasa di f f er entwav el engt h/f r equencyandener gycont ent .Vi ol etl i ghthast hemostener gy whi l er edhast hel east . Quant i f y i ngsol arr adi at i on Al t houghr adi at i onemi t t edf r om t hesuni sf ai r l yconsi st entt her ei ssi gni f i cant v ar i at i oni nt her adi at i onr ecei v edatt heEar t h’ ssur f ace.Thi si scausedbyt heEar t h’ s or bi t( r esponsi bl ef ort heseasons) ,r ot at i ononi t sownaxi s( r esponsi bl ef orni ghtand day )andt heal bedo( cov er edl at er )ofcer t ai nar eas.Sol arar r aydesi gner sneedt obe abl et oquant i f yhowmuchsol arr adi at i onagi v ensi t ewi l lr ecei v et hr oughoutt hey ear . Theamountofsol arener gyr ecei v edbyanar eaov eradayi sr ef er r edt oasi nsol at i on andcanbemeasur edi nkWh/ m2/ dayorpeaksunhour s( PSH) .I ti si mpor t antt onot e t hatmostPVar r ay sar et i l t edatacer t ai nangl eabov et hehor i zont alandt hei nsol at i on ont hehor i zont alpl anewi l ldi f f erf r om t hei nsol at i onont het i l t edpl aneoft hear r ay ; dat ai sof t enav ai l abl ef orbot ht hehor i zont al andv ar i oust i l tangl es.

Peaksunhour sar ev er yusef ul i nsy st em y i el dcal cul at i ons I r r adi at i on: Thet ot al quant i t yofr adi antsol arener gyperuni tar ear ecei v edov eragi v en per i od, e. g.dai l y , mont hl yorannual l y . I nsol at i on: Anot hert er mf ori r r adi at i on.Theamountofsol arr adi at i oni nci dentona sur f aceov eraper i odoft i me.Peaksunhour s( kWh/ m2/ day )ar eameasur ementof dai l yi nsol at i on.

Fi gur e2. 5Dai l yi r r adi ancef orLondon, UK, onahor i zont al pl anemeasur edi nW/ m2and v ar y i ngwi t ht i meofdayandmont h.Sol arener gyv ar i est hr oughoutt hedayandpeaksi n t hemi ddl eoft heday . Exampl e I fsunl i ghti sr ecei v edatani r r adi anceof1000W/ m2f or2hour s, 600W/ m2f or1. 5hour s and200W/ m2f or1hour , t het ot al r adi at i onr ecei v edt hatdayi s3. 1PSH:

1000W/ m2* 2hour s+600W/ m2*1. 5hour s+200W/ m2*1hour =3100W/ m2/ day 3100W/ m2/ day %1000W/ m2/ day 3. 1PSH

Theef f ectoft heEar t h’ sat mospher eonsol arr adi at i on TheEar t h’ sat mospher er ef l ect sal ar geamountoft her adi at i onr ecei v edf r om t hesun–wi t houtt hi spr ot ect i onl i f ecoul dnotbesust ai nedont hepl anet .Whensol ar r adi at i onar r i v esatt het opoft heEar t h’ sat mospher ei thasapeaki r r adi ancev al ueof 1367W/ m2( t hi si sknownast hesol arconst ant ) .Byt het i mesol arr adi at i onr eachest he Ear t h’ s sur f ace i thas a peak i r r adi ance v al ue ofappr oxi mat el y1000W/ m2.The di f f er encebet weent hesol arconst antandt hepeaki r r adi ancev al ueatt heEar t h’ s sur f acei sduet ot heEar t h’ sal bedo– t heamountofsol arener gyr ef l ect edf r om a sur f aceont heEar t hatt hatspeci f i cl ocat i on. Li ghti sr ef l ect edf r om Ear t hi nav ar i et yofway s:  Radi at i oni sr ef l ect edof ft heat mospher ebacki nt ospace.  Radi at i oni sr ef l ect edof fcl oudsi nt hest r at ospher e.  TheEar t h’ ssur f acei t sel fr ef l ect ssunl i ght . Theav er agepor t i onofsunl i ghtr ef l ect edf r om t heEar t h( t heEar t h’ sal bedo)i s30 percent .Pol arr egi onshav ev er yhi ghal bedoast hei ceandsnowr ef l ectmostsunl i ght , whi l eoceanar eashav eal owal bedobecausedar kseawat erabsor bsal otofsunl i ght . I r r adi ancei sacombi nat i onofdi r ectanddi f f user adi at i onandwi l ldependont heal bedo ( r ef l ect edsol arr adi at i on)oft hatpar t i cul arl ocat i on.Thatpr opor t i onofsol arr adi at i on whi chi sscat t er ed,absor bed orr eemi t t ed i nt heat mospher ei sdi f f user adi at i on. Under st andabl yonasunnyday , t hi sscat t er eddi f f user adi at i onwi l l cont r i but eonl yt o10 percentofv i si bl el i ght ,butonacl oudydayt her ewi l lbemuchmor escat t er i ngoft he sol arr adi at i on r eachi ng t he Ear t h’ s sur f ace whi ch means t he amountofdi f f use r adi at i onwi l l bemuchgr eat er .

Fi gur e2. 7Sol arr adi at i oncompr i sesdi r ectanddi f f user adi at i on

Ai rmasswi l l al soaf f ectt hei r r adi anceatal ocat i on.Thegr eat ert heai rmass, t he hi ghert hechanceofl i ghtbei ngr ef l ect edorscat t er ed, meani ngt her ewi l lbel esssol ar r adi at i onr eachi ngt heEar t h’ ssur f ace.Ai rmassof1. 5i st hest andar dcondi t i onat whi chsol armodul esar er at ed.Ai rmasszer or ef er st oai rmassi nspace;ai rmassone cor r espondst ocondi t i onswhent hesuni sdi r ect l yov er head.Regi onsout si det he t r opi cswi l l nev erexper i enceai rmassone, ast hesuni snev erdi r ect l yov er head.

Fi gur e2. 9Fr om t hesur f aceoft heEar t h, ai rmassi sdi r ect l yr el at edt ot heal t i t udeoft he sun

Fi gur e2. 10Atsunsett hesuni sl owi nt heskyandt her ef or eai rmassi sv er yhi gh.Li ght i sscat t er edsomucht hatt hewhi t el i ghti ssepar at edi nt oi t sdi f f er entcol our s.Mostof t hecol our sscat t ersot hatt heyar enotv i si bl ebutr edl i ghtscat t er st hel east ,whi chi s whyweseer edsunset soncl oudyday s.Bl uel i ghti sscat t er edt hemost ,whi chi swhy t heskyi sbl uewhensunl i ghtpassest hr ought hel eastamountofat mospher e( dur i ng t heday )

I nsol at i onv ar i eswi del ydependi ngonl ocat i on( andt i meofy ear )andwhen desi gni ngasy st em i ti sv er yi mpor t antt oconsi dert hesol arr adi at i onchar act er i st i csf or t hespeci f i cl ocat i onwher et hesol arar r aywi l lbei nst al l ed.Fori nst ance,asol arar r ay power i ngahousehol di naGer manci t ywoul dhav et obesi gni f i cant l yl ar gert hanasol ar ar r aypower i ngahousehol dwi t ht hesameener gyconsumpt i oni nt heAust r al i andeser t .  Di r ectr adi at i on: Sol arr adi at i ont hatpassesdi r ect l yt ot heEar t h’ ssur f ace.  Di f f user adi at i on:Sol arr adi at i ont hati sscat t er edorabsor bedbycl oudsand gaseswi t hi nt heat mospher eandt henr eemi t t ed– di f f user adi at i oni sl ess power f ul t handi r ectr adi at i on.  Ai rmass:Thedi st ancet hatr adi at i onmustt r av elt hr ought heat mospher et o r eachapoi ntont hesur f ace.Thi sv al uev ar i est hr oughoutt hedayf oral ocat i on. Sungeomet r y Becauseoft heEar t h’ sor bi tandr ot at i on,t heposi t i onoft hesunr el at i v et oa sol arar r ayi sconst ant l ychangi ng.Desi gner susesev er algeomet r i calt echni quest o desi gnanar r ayt hatwi l lcapt ur et hemostsol arener gypossi bl e.Thel ocat i onoft hesun i sspeci f i edbyt woangl eswhi chv ar ybot hdai l yandannual l y . Sunangl es Sol aral t i t ude: Theangl ebet weent hesunandt hehor i zon; t heal t i t udei sal way s bet ween0°and90° . Azi mut h: Theangl ebet weennor t handt hepoi ntont hecompasswher et hesuni s posi t i oned.Theazi mut hangl ev ar i esast hesunmov esf r om eastt owestacr osst he skyt hr ought heday .I ngener al , t heazi mut hi smeasur edcl ockwi segoi ngf r om 0°( t r ue nor t h)t o359° .

Fi gur e2. 16Thesun’ sal t i t ude

Thesun’ spat hi nt heskyf oranypar t i cul arl ocat i oncanbedepi ct edonat wodi mensi onalsur f acei nasunpat hdi agr am.Thi sdi agr am canbeusedt odet er mi net he posi t i onoft hesuni nt heskyatanyt i meoft heday , f oranydayoft hey ear . Thesunpat hdi agr am i scomposedof :  azi mut hangl es, r epr esent edont heci r cumf er enceoft hedi agr am;  al t i t udeangl es, r epr esent edbyconcent r i cci r cl es;  sunpat hl i nesf r om eastt owestf ordi f f er entdat esi nt hey ear ;  t i meofdayl i nescr ossi ngt hesunpat hl i nes;

 l ocat i oni nf or mat i ont hatr ef er st ol at i t ude. Geomet r yf ori nst al l i ngsol arar r ay s Theposi t i onofasol armodul ei sr ef er r edt oasi t sor i ent at i on.Thi sor i ent at i onof t hesol arar r ayi sv er yi mpor t antasi taf f ect st heamountofsunl i ghthi t t i ngt hear r ayand hencet heamountofpowerpr oduced.Theor i ent at i ongener al l yi ncl udest hedi r ect i on t hesol armodul ei sf aci ng( i . e.duesout h)andt het i l tangl e, whi chi st heangl ebet ween t hebaseoft hesol armodul eandt hehor i zont al .Theamountofsunl i ghthi t t i ngt hear r ay al sov ar i eswi t ht het i meofdaybecauseoft hesun’ smov ementacr osst hesky . I tt hen becomesappar entt hati ft hesuni sov er headandt hesol arpaneli sl ai df l atont he gr ound, i twi l l capt ur eal l t hesun’ sr ay s, asshowni nt hei magebel ow.

Chapt er2 PVI NDUSTRYandTECHNOLOGY Sol arcel l s,al soknownasphot ov ol t ai c( PV)cel l s,ar edev i cest hatpr oduce el ect r i ci t ywhenexposedt osunl i ght .I n1921Al ber tEi nst ei nwont heNobelPr i zei n Phy si csf orhi sdi scov er yoft hephot oel ect r i cef f ectt hati st hesci ent i f i cbasi sf orsol ar cel l s.Sol arcel l swer ef i r stdev el opedi nt he1950sf orusei nspaceexpl or at i on.Theyar e i dealf ort hi sappl i cat i onbecauset heyar er el i abl e,needl i t t l emai nt enance( hav i ngno mov i ngpar t s)andr equi r eonl ysunl i ght , whi chf ort hi susei si nal mostl i mi t l esssuppl y . I nt he21stcent ur ysol arcel l sar eani ncr easi ngl yat t r act i v eener gysour ceconsi der i ng t hepr obl emsposedbygr eenhousegasemi ssi onsanddwi ndl i ngf ossi lf uelener gy r eser v es.Theyar eal sopopul arbecauset heyar ev er yv er sat i l eandcanbeusedona smal lscal e,i . e.on homes or t o power a si ngl e dev i ce such as a r emot e t el ecommuni cat i ons r epeat erst at i on,as wel las f orl ar gescal e poweruse.The pot ent i alf orphot ov ol t ai cshasat t r act edsi gni f i canti nv est mentf r om gov er nment sand busi nessesal lov ert hewor l d.Gl obal l yl abor at or i esar ewor ki ngt oi mpr ov esol arcel l ef f i ci enci es and t o cr eat e mor e power f ulcel l s by f ur t her dev el opi ng exi st i ng t echnol ogi esandbyusi ngnewmat er i al sandmanuf act ur i ngmet hods. Semi conduct ordev i ces Sol arcel l s ar e made f r om semi conduct i ng mat er i al s.Semi conduct or s ar e mat er i al st hatconductel ect r i ci t yundercer t ai ncondi t i ons, sot heyar enei t heri nsul at or s norconduct or s.Themostcommonsemi conduct ormat er i ali ssi l i con.Toi mpr ov ei t s conduct i v i t y ,i ti sof t encombi nedwi t hot herel ement si napr ocessknownasdopi ng. Semi conduct or sar eusedf r equent l yi nel ect r oni cs,i ncl udi ngPV cel l s,l i ght emi t t i ng di odes( LEDs)andmi cr ochi pssuchast hoseusedi ncomput er s. Mai nst r eam t echnol ogi es Si l i con i st he mostwi del y used mat er i ali n sol arcel lpr oduct i on;most commer ci alsol arcel l sar emadeofsi l i con.Si l i coni sext r act edf r om si l i condi oxi de ( al soknownasquar t zi t e) ;quar t zi t ecr y st al sar equar r i edandr ef i nedt oext r actsi l i con

f orsol arcel lmanuf act ur e.Quar t zi t ecr y st al sar eal soamaj orcomponentofsand; howev er ,r egul arsandi st ooi mpur et obeusedi nt hi spr ocess.Si l i coni sav er sat i l e mat er i al :amet al l oi d,i texhi bi t smanyoft hepr oper t i esofmet al s( i . e.i ti sl ust r ousand sol i datr oom t emper at ur e)butal soexhi bi t ssomepr oper t i esofnonmet al s.Ther ear e sev er aldi f f er entt y pes ofsi l i con sol arcel l :monocr y st al l i ne,pol y cr y st al l i ne and amor phoussi l i con. Monocr y st al l i nesi l i con Thesesol arcel l sar epr oducedf r om asi ngl esi l i conseedcr y st alpl acedi na cr uci bl eofmol t ensi l i conanddr awnoutsl owl ywhi l er ot at i ng.I nt hi smanneri ti s possi bl et opr oduceal ar gerpur ecr y st al l i nesi l i coni ngot ,whi chi st hensl i cedi nt o t hi nnerwaf er s.Monocr y st al l i nesi l i consol arcel l sar et hemostef f i ci entandgener al l y t hemostexpensi v e,al t hought hehi gheri ni t i alcostmaybej ust i f i edbyt hei ri ncr eased powerout putast heyar ehi ghl yef f i ci entcompar edt oot hersi l i cont echnol ogi es.The hi ghestr ecor ded ef f i ci encyf ormonocr y st al l i ne si l i con sol arcel l si s 25 percent ; commer ci al l yav ai l abl esol arcel l sar enowbei ngpr oducedwi t hef f i ci enci esof22. 5per centandf i ni shedmodul eswi t hef f i ci enci esof19percent . Mul t i cr y st al l i ne/ pol y cr y st al l i nesi l i con Mul t i cr y st al l i neorpol y cr y st al l i nesi l i consol arcel l sar emanuf act ur edbybl ock cast i ngmol t ensi l i con, sot heyar enotmadef r om asi ngl ecr y st ali ngotbutr at herf r om onecomposedofmanysmal lcr y st al s,whi chgr ow i nr andom or i ent at i onsast he mol t enmat er i alsol i di f i es.Thi spr oducesl oweref f i ci enci est hanmonocr y st al l i necel l s; howev er ,i ti sst i l lav er ypopul art echni quebecausei ti seasi erandl essexpensi v e. Mul t i cr y st al l i neandmonocr y st al l i nesi l i consol arcel l sar et hosemostcommonl yused i nPV ar r ay s,andcommer ci al l yav ai l abl emul t i cr y st al l i nesol arcel l scannow r each l abor at or yef f i ci enci esov er18percent ,wi t ht her ecor df ormodul eef f i ci encybei ng

17. 84percent . Fi g: Mul t i cr y st al l i necel l sar eeasi l yi dent i f i abl ebyt hei rdi st i nctgr ai nst r uct ur ewhi ch gi v esagl i t t er i ngef f ecti nsunl i ght Thi nf i l m sol arcel l s Thi nf i l m sol arcel l sar emadef r om mat er i al ssui t abl ef ordeposi t i onov erl ar ge ar eas.Theyneedonl ybeaboutonemi cr ont hi ck,hencet henamet hi nf i l m( adotsuch as‘ . ’ cov er s615mi cr onsandmul t i cr y st al l i neandmonocr y st al l i nesi l i consol arcel l sar e nor mal l yabout300 mi cr onst hi ck) .I ncr easi ng mat er i alpr i cesand hi ghwor l dwi de demandf oraf f or dabl ephot ov ol t ai cshav el edt oi ncr easi ngi nt er esti nt hi nf i l m sol ar cel l s.Theyar el essexpensi v et omanuf act ur et hancr y st al l i nesol arcel l sandal otof r esear ch hasbeen di r ect ed t owar dsi ncr easi ng ef f i ci enci es,t hecur r entl abor at or y r ecor df ort hi nf i l m sol arcel lef f i ci encybei ng20. 1percent .Howev er ,commer ci al l y av ai l abl et hi nf i l m modul esar ebet ween6and12percentef f i ci ent .Thi nf i l m cel l sar e bei ngusedmor eandmor ef r equent l yi nbui l di ngsandar eof t enusedf orgadget ssuch assol ar power edwat chesandcal cul at or s.

Amor phoussi l i conmodul esar eeasi l ydi st i ngui shedf r om cr y st al l i nemodul esbyt hei r dar kanduni f or m col ourbutt heyal sol ookl i kenonsi l i conet hi nf i l m modul es

Cont act s Forei t herPVcel l sormodul est owor k, t heyneedel ect r i cal connect i ons.Asol arcel l has el ect r i cal connect i onspr ov i dedbymet al conduct i ngst r i pst hatcol l ectel ect r ons pr oducedi nt hecel l andal l owt hi scur r entt of l owt hr ought heci r cui t s.Thesemet al st r i psar eknownascont act sandt her ear esev er al di f f er entcont actt echnol ogi es cur r ent l yi nuse.Themostcommonwayt omanuf act ur esol arcel l si sbyscr eenpr i nt i ng, wher et hemet al i ssi mpl ypr i nt edont ot hecel l .Thi smet hodi sv er yr el i abl eandi s t y pi cal l yappl i edt osol arcel l spr oduci ngef f i ci enci esofabout12–15percent .Sev er al f act or sneedt obebal ancedwhenusi ngscr eenpr i nt i ng: I ft her ei st oomuchspace bet weent hecont act s, t hecel l wi l l bel essef f i ci ent .I ft hear eacov er edbyt hecont act s i st ool ar ge, t hecel l wi l l r ecei v el esssunl i ghtandpr oducel esspower .Fort hecont act s t obeef f ect i v e, t het opoft hecel l of t enneedst obet r eat edi nsuchawayt hati t s absor banceofhi ghener gybl uel i ghti sr educed.Anot hermet hodusedby manuf act ur er st oachi ev esol arcel l ef f i ci enci esov er20percenti sr earorback cont act s.Thi st echnol ogyi ncr easest hewor ki ngcel l ar ea, al l owsasi mpl i f i ed aut omat edpr oduct i onandt hecel l wi r i ngi shi ddenf r om v i ew.Themostef f i ci ent commer ci al l yav ai l abl esi l i consol arcel l suser ear cont act s( 18–23percent ) .Ther ei snomet al ont hef r ontoft hecel l , whi chmeanst he whol ecel l i spr oduci ngel ect r i ci t y .Thehi ghestef f i ci encysi l i concel l s( 25percent l abor at or yef f i ci ency )der i v ef r om anot hermet hodknownasbur i edcont actsol arcel l s ( BCSC) .Thi smet hodusessmal l l asergr oov eswhi char ecuti nt hecel l andt hemet al i s i nser t edi nt ot hegr oov e.Bur i edcont actandr earcont actt echnol ogi esar e adv ant ageousbecauset heysol v emanyoft hepr obl emsassoci at edwi t hscr een pr i nt i ng.Bur i edcont act scov erv er yl i t t l esur f acear eabecausemostoft hecont acti s i nsi det hegr oov e.Thi smeanst heydon’ tbl ockasmuchsunl i ghtandt hecont act scan bev er ycl oset oget herbecauset heyar esot hi n.Thesi desoft hegr oov esar et r eat ed i nst eadoft het op, sot hePVcel l ’ sabsor pt i onofbl uel i ghti snotaf f ect ed.Rearcont act s al soel i mi nat emanyoft hesepr obl ems, becauset heyar el ocat edatt hebackoft hecel l , t heydonotshadet hecel l andsot henumberoft hesecel l cont act scanbei ncr easedt o i mpr ov ecel l ef f i ci ency .

Themet al cont act sont hi spol y cr y st al l i necel l ar ecl ear l yv i si bl e

Fr ontandbackofSunPowerr ear( back)cont actmonocr y st al l i nesi l i consol arcel l

Scr eenPr i nt edSol arCel l

Bur i edCont actSol arCel l

Wal es BCSCt echnol ogyi susedt omanuf act ur esol arcel l swi t hmuchhi gheref f i ci enci est han t hoset hatusescr eenpr i nt i ng.Howev er , scr eenpr i nt i ngi sst i l l t hedomi nantf or m of cont actmanuf act ur i ngbecauseofi t st echni cal si mpl i ci t yandcostef f ect i v eness

Buy i ngsol armodul es Manydi f f er entPVmodul esar eav ai l abl ewor l dwi de.I tcan,howev er ,bedi f f i cul t t odet er mi newhet hert hepr oduct sandsuppl i er sar er el i abl e.I ti si mpor t antt obeabl e t oensur et hatt hePV modul esandt heel ect r i cali nst al l at i onar esaf eandofgood qual i t y .Poorpr act i ceandsubqual i t ypr oduct sposeser i ousr i skst ot hesaf et yand f i nanci alv i abi l i t yoft hi si nv est ment .Out l i ned bel ow ar ef act or st o consi derwhen pur chasi ngaPVsy st em, bear i ngi nmi ndt hatagoodsy st em shoul dnotonl yphy si cal l y l astf ort hedur at i onoft hewar r ant ybutal sowor kef f ect i v el ydur i ngt hatt i me.Thi s meanst hatt hemodul es,addi t i onalequi pment( di scussedi nChapt er5) ,mount i ng f r ame( di scussedi nChapt er6)andr oofmustal ll astasl ongast hemodul esorbe r epl aced dur i ng t hatt i me.Sol armodul es ar e sol d wi t hal engt hymanuf act ur er ’ s war r ant y ,e. g.25y ear sf or80percentofout put .Whi l et heguar ant eedout putmustbe i ncl udedi nanysy st em out putest i mat es, t hebuy erneedst ounder st andt hati ft heyar e i nst al l i ngapr oductwi t hsuchapot ent i al l yl ongwar r ant y , t hest r uct ur e( e. g.t hebui l di ng andr oofi t sel f )andot hersy st em component sneedt ol astasi mi l arl engt hoft i me.For someequi pment , i . e.t hei nv er t er , ar epl acementmaybepl annedov ert hel i f eoft hePV sy st em. St andar ds The PV i ndust r yi s gr owi ng r api dl y ,r esul t i ng i n many new manuf act ur er s pr oduci ngPV modul es.I ti si mpor t antt hatonl yqual i t ymodul esar ei nst al l edand st andar dsdoexi st .Themostcommonst andar dsappl i cabl et oPVmodul esar e:I EC 61215Cr y st al l i nesi l i cont er r est r i alphot ov ol t ai c( PV)modul es–Desi gnqual i f i cat i on andt y peappr ov al .I EC61646Cr y st al l i net hi nf i l mt er r est r i alphot ov ol t ai c( PV)modul es –Desi gnqual i f i cat i onandt y peappr ov al .I EC61730Phot ov ol t ai c( PV)modul esaf et y qual i f i cat i on– Requi r ement sf orconst r uct i onand r equi r ement sf ort est i ng.These

st andar dsor i gi nat ef r om t heI nt er nat i onalEl ect r ot echni calCommi ssi on:www. i ec. ch.I n manycount r i esaPVmodul emustev i dencecompl i ancewi t hei t herI EC61215orI EC 61646( dependi ngonwhet heri ti st hi nf i l m orcr y st al l i nesi l i cont echnol ogy )andI EC 61730. Cer t i f i cat i ons Qual i t ymodul esshoul dcompl ywi t ht heI ECst andar dsbutmayal soadher et o l ocalst andar ds.Cer t i f i cat i onsgener al l yensur et hatmodul esadher et oal lr el ev ant st andar dsi naddi t i ont ot hespeci f i cphot ov ol t ai csst andar ds; War r ant i es PVmodul esar et y pi cal l ysuppl i edwi t ht hr eel ev el sofpr oductwar r ant y : 1, 2-or3 y earwar r ant yon t he phy si calmanuf act ur e oft he modul ei t sel f ,i . e.t he f r ame, encapsul ant ,gl ass,modul ej unct i onboxet c. ;10–12y earwar r ant yt hatt hemodul ewi l l pr oduce90percentofi t sr at edout put ;20–25y earwar r ant yt hatt hemodul ewi l l pr oduce80percentofi t sr at edout put .I fanyoft hesecondi t i onsar enotmet ,t he quest i onofawar r ant ycl ai m wi l ldependont hemanuf act ur er ’ spubl i shedwar r ant y and/ ort hecommer ci all awsoft hecount r ywher et hemodul ewaspur chased.For exampl e,i fsomeonebuy samodul ef r om ov er seasandi mpor t si tf orsal eort hei rown use, t heni ti sassumedt hatt heyunder st andt hatt heyhav et osendt hemodul ebackt o wher et heypur chasedi tt ocl ai m war r ant y .I fani mpor t edmodul ei spur chasedf r om a ‘ r esel l er ’ oft hepr oduct , i . e.nott hemanuf act ur eri t sel fort hei ragent , t her esel l ermi ght hav eanar r angementwi t ht hemanuf act ur ert hatal lwar r ant i esar ehandl edbyt he manuf act ur erdi r ect l y or ,i n some count r i es,t he i mpor t eri s deemed t o be t he manuf act ur er ,soal lwar r ant i esr estwi t ht hem.PVmodul esar eext r emel yr el i abl eand st abl epr oduct s,buti ti sst i l ladv i sabl et of i ndoutt hewar r ant ypr ov i si onsofany pr oductbei ngconsi der edf orpur chaseandi nst al l at i on. Emer gi ngt echnol ogi es Besi deswel l est abl i shedmai nst r eam t echnol ogi esmanynew t echnol ogi esar e emer gi ng.Somebui l donexi st i ngknowl edgeandr esear chwhi l eot her si ncor por at e

i nnov at i v enewmat er i al sandt echni ques. Dy esensi t i zedsol arcel l s Dy esol arcel l sar est i l l t echnol ogi cal l yi mmat ur e.Att heat omi cl ev el t heyoper at e v er ydi f f er ent l yf r om ot hersol arcel l sanddonotusesi l i con.Dy esol arcel l suset i t ani um di oxi de( al sousedi nt oot hpast e)andcol our eddy es;t heycanbemanuf act ur edata muchl owercostt hanot hersol arcel l sandwor kbet t eri nl owl i ght .Dy esol arcel l sar e t r anspar entandcanbepr oducedi nmanydi f f er entcol our s,maki ngt hem i dealf or ar chi t ect ur alappl i cat i onsaswi ndows.Dy esol arcel l sal sohav epot ent i ali nmi l i t ar y appl i cat i onsast heycanbemadei ncamouf l agepat t er ns.Cur r ent l yt hehi ghestcel l ef f i ci encyachi ev edi nal abor at or yi s12percentandcel l swi t hanef f i ci encyof7per centar ei npr oduct i on.

Dy esol arcel l sar eav ai l abl ei nar angeofat t r act i v ecol our sandar et r anspar entsot hey canbei nt egr at edi nt ot hef acadeofabui l di ng

Sl i v ercel l s Sl i v ercel l swer edev el opedatt heAust r al i anNat i onalUni v er si t yandar ev er yt hi n monocr y st al l i nesi l i consol arcel l s.Theyar euni queassi l i concel l sbecauset heyar e bi f aci al( t heycanabsor bl i ghtf r om bot hdi r ect i ons) .Sl i v ert echnol ogyhasachi ev edcel l ef f i ci enci es ofov er19 percentand modul e ef f i ci enci es of13. 8 percent .The t echnol ogyi si ni t sear l yst agesofcommer ci al i zat i onbutshowsal otofpot ent i alf or

appl i cat i onsi nbui l di ngi nt egr at edphot ov ol t ai cs.

Sl i v ercel l sar eal sot r anspar entandf l exi bl e

Het er oj unct i onwi t hi nt r i nsi ct hi nl ay er( HI T)phot ov ol t ai ccel l s HI Tmodul esusebot hcr y st al l i nesi l i consol arcel l sandamor phoussi l i cont hi n f i l m t echnol ogy and hav e achi ev ed modul e ef f i ci enci es of17 percentand cel l ef f i ci enci esof22percent .

I I I VSemi conduct or s I I I Vorext r i nsi csemi conduct orsol arcel l suseanel ementf r om gr oupI I Ioft he per i odi ct abl eandanel ementf r om gr oupV( asopposedt osi l i conwhi chi sagr oupI V el ement ) , suchasgal l i um ar seni dewhi chi scommonl yusedi nspacegr adesol arcel l s. Thesesol arcel l sar ecommonl ymul t i j unct i onsot heyar ei nf actmanyl ay er sofsol ar cel l s,whi ch wi l lcol l ectdi f f er entcol our sofv i si bl el i ght .Theyal so f r equent l yuse adv ancedsol arconcent r at ort echnol ogyt omaxi mi zei ncomi ngsol arr adi at i on.Ext r i nsi c semi conduct ormul t i j unct i onsol arcel l sar et hemostef f i ci entandmostexpensi v e t echnol ogyont hemar ket .Thehi ghestr ecor dedl abor at or yef f i ci encyi s41. 6percent andi shel dbySpect r ol abI nci nt heUS.Duet ot hei rhi ghcost , I I I Vsemi conduct orcel l s ar enor mal l yusedf orspaceappl i cat i onssuchassat el l i t esorot herbi gbudget ,hi ghper f or mance, sol ar power eddev i cessuchassol arpl anesandsol arr aci ngcar s.

Sol arconcent r at or s Sol arconcent r at or sar eusedt oi ncr easet hei nt ensi t yofl i ghthi t t i ngt hecel lso t hati twi l lgener at emor eel ect r i ci t y( t heout putpowerpr oducedbyasol arcel li s dependentont hei nt ensi t yofl i ghthi t t i ngt hatcel l ) .Ther ear emanydi f f er entki ndsof sol arconcent r at or sav ai l abl ef orav ar i et yofappl i cat i ons,butt hemostcommonar e l ensesorr ef l ect i v et r oughsusedt of ocusl i ght .Sol arconcent r at or sar eadv ant ageous becauset heyi ncr easet hepowerout putsot hatt hesy st em r equi r esf ewersol arcel l s ( sol arcel l sar eal way st hel ar gestcostwheni nst al l i ngasy st em) .Manyoft hesecel l s r equi r eacool i ngsy st em t oper f or m wel l ,ascel lt emper at ur escangetv er yhi gh. Chal l engest ot hi st echnol ogyi nv ol v edev el opi ngconcent r at or st hatar est ur dyand r el i abl eenought osur v i v edecadesi nsol ari nst al l at i ons, somet i mesi nhar shcondi t i ons suchasdeser t , andt okeepcost sasl owaspossi bl e.

Themi r r or sei t hersi deoft hemodul ear eusedt oconcent r at el i ghtandi ncr ease powerout put

Chapt er3 PVCELLS, MODULESANDARRAYS

Char act er i st i csofPVcel l s Eacht y peofPVcel li suni queandhasi t sowni ndi v i dualchar act er i st i cs; i ti sv er y i mpor r antt obeawar eoft hi swhendesi gni nganar r ayast hechar act er i sr i csoft hecel l s i nonet y peofmodul ecanaf f ectt hepowerout putoft heot hermodul esconnect edt oi t . Gr aphi cr epr esent at i onsofPVcel l per f or mance I ti sv er ycommonf ort hef eat ur esofaPVcel lt ober epr esent edgr aphi cal l yasa cur r ent v ol t age ( orI V)cur v e.An I V cur v et r ackst he PV cel l ’ sper f or mance and hi ghl i ght skeyf eat ur essuchasVoc,I scandPmax.APVcel lwi l lal way soper at eal ong t hi scur v e,i . e.atagi v env ol t age;t hecur r entpr oducedwi l lal way shav et hesamev al ue andv i cev er sa. Apowercur v ei susedt of i ndt hemaxi mum powerpoi nt ( Maxi mum powerpoi nt : Thet heor et i calmaxi mum powerout putofaPVcel l .Themaxi mum powerpoi nt( Pmax) i st hepr oductoft hemaxi mum powerpoi ntv ol t age( Vmp)andt hemaxi mum power poi ntcur r ent( I mp) . ) .Apowercur v epl ot st hev ol t ageal ongt hehor i zont alaxi sandt he power( cur r entmul t i pl i edbyv ol t age)al ongt hev er t i calaxi s.Whent hi si ssuper i mposed ont heI Vcur v ef ort hesamecel l ,i ti sv er ycl earwher et hemaxi mum powerpoi ntl i es. The I V and powercur v es ar ei mpor t antbecause i ti s necessar yt o know t he

char act er i st i csofeachi ndi v i dualcel lwhendesi gni ngamodul e.Connect i ngcel l swi t h dr amat i cal l ydi f f er entchar act er i st i cst oget herwi l lhav eal ar ge( gener al l ynegat i v e) ef f ectont hepowerout putoft hePVmodul e.

VocandI scar et hexandyi nt er cept sr espect i v el y .I deal l yt hePVcel l oper at esar ound t hekneeoft hecur v e, wher et hemaxi mum powerpoi nti sl ocat ed

Pmpi st hehi ghestpoi ntont hepowercur v e; by ext r apol at i ngbackt ot hexaxi s, Vmpcanbef ound.Vmpi sal soont heI Vcur v eandso t hecor r espondi ngcur r entcanbef oundf ort hi spar t i cul arv ol t age( I mp)

PVMODULESANDARRAY

Si ngl ephot ov ol t ai cmodul e; t hemodul e’ s36cel l scanbeseenar r angedi na4x9gr i d

Vi ewbeneat haPVar r ay

PVar r aycomposedofmonocr y st al l i nemodul es Connect i ngPVcel l st ocr eat eamodul e PV cel l sofi dent i calchar act er i st i csar ewi r edt oget heri nser i est ocr eat ea modul e.I nser i es,t hei rv ol t ageswi l laddwhi l et hecur r entr emai nsconst ant ,i . e.t he cur r entoft hemodul ei sequalt ot hecur r entofonecel l .Powerl ossesoccurwhenacel l i sunder per f or mi ng.I tmaybedamagedormor ecommonl yshadedandt hi swi l lbe di scussed l at eri nt hi s chapt er .The char act er i st i cs ofcel l s ar e gi v en on t he manuf act ur er ’ sdat asheet ,f r eel yav ai l abl eont hemanuf act ur er ’ swebsi t e;t hesear e usedt odesi gnaPVar r ay .Desi gner sshoul dal way scont actt hemanuf act ur ert omake sur et hedat asheetont hei rwebsi t ei scur r ent . Speci f i cat i onsheet s PV modul es pur chased f r om r eput abl e manuf act ur er s shoul d come wi t h speci f i cat i onsheet s( al soknownasdat asheet s) .A dat asheeti ncl udesi mpor t ant t echni cali nf or mat i onr equi r edt odesi gnandi nst al laPVar r ay .I tmayal sobeusef ulf or aconsumert ol ookatt hedat asheetwhencompar i ngdi f f er entmodul esasi tpr ov i des basi ci nf or mat i onaboutef f i ci ency , r at edpowerandphy si cal si ze.

Cr eat i ngast r i ngofmodul es Ast r i ngcompr i sesanumberofPVmodul esconnect edi nser i es.Theel ect r i cal char act er i st i csofPVmodul esconnect edi nser i est of or m ast r i ngar et hesameasPV cel l sconnect edi nser i est of or m amodul e:meani ngt heout putv ol t ageoft hest r i ngwi l l bet hesum oft heout putv ol t agesofal l t hemodul esandt heout putcur r entoft hest r i ng

wi l lbet hel owestout putcur r entofanymodul e.Modul escanal sobeconnect edi n par al l el .I nt hi scaset hecur r entout putoft hemodul eswi l laddi nst eadoft hev ol t age. Theout putv ol t agei st hatofasi ngl emodul e.

Whent hr eei dent i cal modul esar econnect edi nser i est of or m ast r i ngt hei rv ol t ages addandt het ot al cur r enti st hatofonesi ngl emodul e.Thepowerout putoft hest r i ngi s cal cul at edusi ngP=IxV

Whennoni dent i cal modul esar econnect edi nser i est hev ol t ageswi l l st i l l add; howev er , t hecur r entoft hest r i ngwi l l bet hel owestcur r entofanysi ngl emodul e( i nt hi scase4A) . Thepowerout putoft hest r i ngi st hencal cul at edusi ngP=IxV

Thr eei dent i cal modul esar econnect edi npar al l el ; t het ot al cur r enti st hesum ofeach i ndi v i dual cur r ent , whi l et het ot al v ol t agei st hev ol t ageofasi ngl emodul e.Thepoweri s onceagai ncal cul at edusi ngP=IxV

Whennoni dent i cal modul esar econnect edi npar al l el t hecur r ent saddwhi l et heout put v ol t agei sequal t ot hel owestsi ngl emodul ev ol t age.Thepowerout putoft hemodul es i st hencal cul at edusi ngP=IxV Cr eat i nganar r ay Ar r aydesi gner swi l lconnectPV modul esusi ngacombi nat i onofser i esand par al l elt opr oducet heout putcur r entandv ol t agesui t abl et oamar ketappl i cat i on. Modul esar et y pi cal l yconnect ed i n ser i est of or m a st r i ng and t hesest r i ngsar e

connect edi npar al l elt of or m anar r ay .Asdi scussedear l i eri nt hechapt er ,PVar r ay s pr oduceDCpowerwhi l et hemai nsr equi r eACpower .Ani nv er t eri sr equi r edt oconv er t t heDCsol arpowert oACpowerandt hear r ayi swi r edi nsuchawayt hatt hemaxi mum powerpoi ntv ol t ageoft hear r ayl i eswi t hi nt her angeoft hegr i di nt er act i v ei nv er t er

Thepr ocessofmaki nganar r ay ; st ar t i ngf r om cel l s, modul esar ecr eat ed, t hen connect edi nser i est of or m st r i ngsandf i nal l yst r i ngsar econnect edi npar al l elt omake anar r ay Phot ov ol t ai car r ayper f or mance Theper f or manceofaPV ar r ayi saf f ect edbyav ar i et yoff act or s:t hemost si gni f i cantoft hese( t emper at ur e, i r r adi anceandshadi ng)ar edi scussedher e. I r r adi anceTheamountofsol arr adi at i on( sunl i ght )hi t t i ngt hecel lwi l ll ar gel y det er mi ne i t s powerout put .The out putofa PV ar r ay can be est i mat ed usi ng per f or mancedat apr ov i dedbyt hemanuf act ur eront hedat asheet .Al lar r ay shav ea r at edpeakpowerout put ,i . e.anar r aycanbedescr i bedasa1. 5kWpar r ay–meani ng

t hatPVi si nst al l edt opr ov i dea1. 5kW peakofpower .Thi s out puthasbeendet er mi nedbyt hemanuf act ur erusi ngst andar dt estcondi t i ons. Usi ngt hi si nf or mat i onandl ocalsol ari nsol at i ondat a( seeChapt er2) ,i ti spossi bl et o est i mat et heout putofanar r ay .

Tocal cul at et hepowerout putofanar r ay , f i r stcal cul at et heout putofeachst r i ng( as expl ai ned pr ev i ousl y )andt hent r eatt hest r i ngsast hought heywer emodul esandcal cul at et he powerout putbyaddi ngt hem i npar al l el

Exampl e Onacl earsunnydaya2kWpPVar r ayr ecei v ed6peaksunhour s:t he6peaksun hour sequat et o an ener gyi nputof6000W/ m2 perday .Expect ed out putcan be det er mi nedasf ol l ows:peakpowerout put×peaksunhour s=expect edout put2kW ×

6PSH =12kWhThePV ar r aypr oduced12kWhf ort hatday( bef or eanypowerl oss f act or sar eaccount edf or ) .Ther ewi l lbev ar y i ngi nsol at i ondat aav ai l abl eonamont hl y basi s, sot hewhol ey ear ’ sout putf r om t hePVar r aycanbeest i mat edf r om t hemont hl y dat a.Howev eri ti si mpor t antt onot et hatt hi st echni quei snev erusedi npr act i ce because a PV sy st em wi l lr ar el y exper i ence STC.Chapt er9 demonst r at es how desi gner saccountf ort hepowerl ossest hatoccurwhent hemodul esar enotoper at i ng atSTC. Temper at ur e Notonl ydoest hesol arr adi at i onhi t t i ngt hemodul espr oduceel ect r i ci t y ,i tal so heat supt hemodul es.I ti snotuncommonf oraPVmodul et or each70° Conasunny day i nat emper at e cl i mat e.As t emper at ur ei ncr eases,t he openci r cui tv ol t age decr easesr api dl ywhi l et heshor t ci r cui tcur r enti ncr easessl owl y .Powerout puti s v ol t agemul t i pl i edbycur r entandsowi l l decr easeaswel l .

TheI Vcur v esf oracel l oper at i ngatdi f f er enti r r adi ancev al uesshowt hei ncr easei n powerout putwi t hi r r adi ance.

Aspower=cur r entxv ol t age( IxV) , asv ol t agedecr eases, powerdecr eases

I nar east hatexper i enceext r emel ycol dt emper at ur es, t hev ol t agei ncr easesast he ambi entt emper at ur edecr eases

Shadi ng PV cel l sr equi r esunl i ghti nor dert opr oduceel ect r i ci t y .I facel lr ecei v esno sunl i ghtduet oshadi ngi twi l lnotpr oduceanypower( ev enasmal lar eaofcel lshadi ng can r esul ti nal ar ge r educt i on i n powerout put ) .Cel l si n modul es ar e nor mal l y connect edi nser i es,sowhenoneorsev er alcel l sar eshaded,t hecur r entout putoft he modul ewi l lber educed.I ft hemodul ei spar tofanar r ay ,t hent hecur r entout putoft he ar r aywi l lal sober educed.Thi swi l lal sooccuri facel li sdamagedandunabl et o

pr oducepower .Shadi ngoft hear r aycanl eadt oi r r ev er si bl edamage.Hotspotheat i ng occur swhenacel li sshadedsucht hati t spowerout puti sr educedandmostoft he cur r entbei ngpr oducedbyt heot her( unshaded)cel l si sf or cedt hr ought hatonecel l causi ngi tt oheatup.Thi sof t enl eadst ocel ldamage( cr acki ng)andcanal sodamage t hegl assencapsul at i on.I ti sdi f f i cul tt opr ev entshadi ng.Howev er ,di odescanbeused t omi t i gat et empor ar yshadi ng( i . e.l eav est hatmayhav ef al l enont hear r ay ) .Whena cel li sshadedordamaged, adi odecanbeusedt ogi v ecur r entanot herpat ht of ol l ow.I t wi l lski pt hedamagedorshadedcel lcompl et el yandhav emi ni mum i mpactont he powerout putoft hear r ay .Thi ski ndofdi odei sr ef er r edt oasaby passdi odeand manuf act ur er st y pi cal l yi nst al l one, t woort hr eeby passdi odespermodul e.

Veget at i on, chi mney s, bui l di ngs, di r tandsnowcanal l shadeaPVmodul e

Ev ent hi ssmal l shadowcanr educet heamountofel ect r i ci t yamodul epr oduces– asmal l shadedar eacan, undercer t ai nci r cumst ancesr educemodul eout putby80–90 percentaswel l asaf f ect i ngt her estoft hear r ay