seminar report on electronics

7/28/2019 Seminar Report on electronics

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1.INTRODUCTIONEvery day, the sun radiates (sends out) an enormous amount of energycalled

solarenergy.Itradiatesmoreenergyinonesecondthantheworldhasusedsincetimebegan.Thisenergycomesfromwithinthesunitself.

Likemoststars,thesunisabiggasballmadeupmostlyofhydrogenandhelium

gas.Thesunmakesenergyinitsinnercoreinaprocesscallednuclearfusion.Onlyasmallpartofthesolarenergythatthesunradiatesintospaceeverreaches

theearth,butthatismorethanenoughtosupplyallourenergyneeds.Everyday

enoughsolarenergyreachestheearthtosupplyournationsenergyneedsfora

year!

Solarenergy,radiantlightandheatfromthesun,hasbeenharnessedbyhumanssinceancienttimesusingarangeofever-evolvingtechnologies.Solarradiation,

alongwithsecondarysolar-poweredresourcessuchaswindandwave

power,hydroelectricityandbiomass,accountformostoftheavailablerenewable

energyonearth.Onlyaminusculefractionoftheavailablesolarenergyisused.

Solarpoweredelectricalgenerationreliesonheatenginesandphotovoltaics.Solar

energy'susesarelimitedonlybyhumaningenuity.Apartiallistofsolar

applicationsincludesspaceheatingandcoolingthroughsolararchitecture,potable

waterviadistillationanddisinfection,daylighting,solarhotwater,solarcooking,

andhightemperatureprocessheatforindustrialpurposes.Toharvestthesolar

energy,themostcommonwayistousesolarpanels.

Solartechnologiesarebroadlycharacterizedaseitherpassivesolaroractive

solardependingonthewaytheycapture,convertanddistributesolarenergy.

Activesolartechniquesincludetheuseofphotovoltaicpanelsandsolar


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Page |3theothersgiveoutpollutinggasesandparticulatesthatareunhealthyforthe

environment,butwindenergysolvesthatproblemquiteeffectively.

2.Asmentionedbefore,themainfunctionofwindenergyoranyotherformof

renewablesourceofenergyistoreducethepressureofglobaldemandonfossil

fuelsthatisshorteningtheiralreadylimitedlife.Iftheareasthataresuitablefor

harvestingwindenergystarttorelyonitinsteadofrelyingontraditionalsources

ofelectricity,thenthisgoalcanbeachievedeffectively.

3.Averysignificantadvantagethatwindmillshaveoverthetraditionalpower

stationsisthefactthattheyrequiremuchlesserareatosetup.Notonlydoesthis

advantagemakeitcheapertosetthemillupasonewouldrequirelessland,butone

mustalsonotforgetthattheareaaroundthewindmillcanthenbeusedforsetting

upadjacentfarmsalso,whichinfactisoftenthecaseatplaceslikethis.

4.Justaswithharvestingsolarenergy,earlieritusedtobequitecostlyto

effectivelyutilizethepowerofwind.Eventhen,thetotalenergythatwas

successfullyconvertedtoelectricitywashardlyenough.Inotherwords,thewind

energyconversionrateswerepoor,butastechnologyhaveimprovedoverthe

years,ithasnowbecomepossibletoutilizeandconvertwindenergyatamuch

lowercostandasignificantlyhigherconversionratio.

5.Tosetupapowerstationtosupplyelectricityinremoteandsecludedplacesat

higheraltitudesisnotaneasyjob.Itwouldrequirealotofmoneyaswellaseffort

andeventhenitmaytakequitesometimebeforeitcanevenbesuccessfully

operated.Thisiswheretheutilityofwindturbinesarefullyrealized.Mountainous

localitiesusuallyhaveanatmospherewherethewindisverystrongaswellbeing

reliablyconsistent.Settingupawindturbinebigenoughtoservetheelectrical


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Page |4needsoftheentirelocalitywouldnotonlybecheaperinthiscase,butitwillbe

muchfasterandperhapsevenmoreusefulaswell.

6.Thesimilaritybetweensolarenergyandwindenergyisthatbothofthemare

renewableandfreesourcesofenergy;whatismoreinterestingisthatitispossible

toinstallasystemthatwillmakeboththealternativesourcesofenergywork

togethertoofferanevenmorereliableandpowerfulenergysource.Theuseof

suchahybridsystemisnotonlylimitedtounderdevelopedareas,becauseevenin

thedevelopedareaswheretraditionalpowerstationsarealreadywellsetup,it

couldsavealotofmoneyandnon-renewableenergy.

7.Itishardtobelieveandmayevencomeasasurprisetosomeonewhodoesnot

havetheknowledge,butthecostofproducingwindenergyhasbecomealmost

80%cheaperthanwhatitusedtobetwentyorthirtyyearsago.Asthetechnology

isstilldevelopingtomakethewindmillsmoreproductiveandlesscostly,wecan

almostassumethatthepriceswillcomedownfurtherandsomedayitmighteven

bethecheapestalternativeforelectricityproductioninthemarket.

8.Itisnosecretthatpetroleumischieflysaturatedincertaingeographicalareas

whichcomewithinthenationalbordersofthecountriesthatarelocatedinthat

particulargeographicarea.Thishascreatedacertainkindofmonopolyandhasalso

raisedthepriceoffuelquitesignificantlyinallthecountriesthataredependenton

it.Windenergyissomethingthatcannotbemonopolizedinthiswayasitisfree

andcannotbeconfinedwithinthegeographicalboundariesofacountryeither.

Therefore,ifinthenearfuture,windenergycanbemademoreusableandmore

efficient,wecanalsohopetoreducethehikedupoilpricesaswell.


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Page |54.SOLARENERGYOVERVIEWSolarenergyisallaboutharnessingthepowerofthesuntoproduceenergy.The

sunrainsenoughsolarenergyontheEarthinonedaytopowertheentireenergy

needsoftheworldforoneyear.Solarenergyisconsideredarenewableenergy

sourcebecauseitwillexistforaslongasoursundoes,estimatedtobeanother4.5

billionyears.Solarenergyisalsoconsideredacleanenergybecauseitdoesnot

producepollutantsorbyproductsharmfultotheenvironment.

Solarenergywasthefirstenergysourceusedbymankind.Ofcourse,theusewas

limitedtodryingthingsandheatingcausedbydirectcontact,butitwasause.In

moderntimes,solarenergyhasbeenapowersourcesincetheearly1950s,butwas

notwidespreadduetotechnologicalissueswhichrendereditanineffectiveand

expensiveenergysource.Withtechnologyadvancements,solarenergyismoving

totheforefrontasapotentialalternativetofossilfuels.

Thefutureisindeedbrightforsolarenergyasnewsolarnanotechnologyiscloseto

creatingsolarplatformsthatbogglethemind.Forinstance,afewcompaniesare

tryingtocreatesolarquantumdots,whichwillbemixedinthepaintyouusefor

yourhome.Yes,youwillactuallypaintonsolarenergypanelsthatwillpower

yourhome

Currently,solarenergyisproducedprimarilythroughtheuseofsolarcells,also

knownasphotovoltaiccells.Theprocessworksbyplacingthecellsindirect

sunlight.Sunhitsthecellscausingachemicalreactionthatcreatesanelectric

current.Thecurrentisthenturnedintoelectricity.Theproblemwiththesecells,

however,istheyareonlyabout15percentefficient.


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Page |6Solarenergyistypicallyclassifiedintwoways,passivesolarandactivesolar.

Bothapproachesproducesolarenergy,butinverydifferentways

Passivesolarisexactlywhatitsoundslike.Itdoesnotinvolvepanelsystemsor

othermovingmechanismstoproducesolarenergy.Instead,passivesolarinvolves

planningastructureinsuchawayastocapturethepowerofthesunwith

windows,tanksandsoon.Thesesystemscanbeusedtoheathomes,waterandso

on.

Activesolarenergysystemstypicallyinvolvesomeformofsolarpanels.The

panelsareorientedtomaximizeexposuretothesun.Dependingonthesystem,the

panelswilltheneitherdirectlyconvertsunlighttoelectricity,whichisthen

transformedfromdirectcurrentelectricitytoalternatecurrentelectricityandstored

inbatteriesorfedintothegridsystemofthelocalutility.Activesystemsaremore

expensiveandcomplex.

Solarenergyhasnumerousadvantagesoverotherenergyplatforms.Itisproduces

nopollution,requireslittlemaintenanceandcomeswithsignificantfinancial

incentivesintheformoftaxdeductions,taxcreditsandrebatesfrommanufactures.

Inamajorityofstates,solarenergycanalsobesoldbacktoutilitiesperaconcept

knownasnetmetering.Thisreducestheneedforbatteriesandsignificantlycuts

utilitybills.

Unfortunately,solarenergyhassomedisadvantagesaswell.Theinitialcostof

purchaseandinstallationcanbeexpensive.Second,areaswithlimitedsunlightare

problematic.Third,solarenergyobviouslycan'tbeproducedatnight.Despite

thesedisadvantages,solarenergyisaboomingenergyplatform.


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Page |7ThelargestproducersofsolarenergyintheworldareGermany,Japanandthe

UnitedStates.Californiahasrecentlyintroducesasolarinitiativedevotingover

threebilliondollarstopromotingsolarenergyusebyresidentsinthestate.Asthis

overviewdemonstrates,thesolarenergyplatformiscomingonstrong.

Solarwaterheating

Solarwaterheating(SWH)systemscompriseseveralinnovationsandmanymaturerenewableenergy(orSHWSolarHotWater)technologieswhichhavebeen

acceptedinmostcountriesformanyyears.SWHhasbeenwidelyusedinGreece,

Turkey,Israel,Australia,Japan,AustriaandChina.

Ina"close-coupled"SWHsystemthestoragetankishorizontallymounted

immediatelyabovethesolarcollectorsontheroof.Nopumpingisrequiredasthe

hotwaternaturallyrisesintothetankthroughthermosiphonflow.Ina"pump-

circulated"systemthestoragetankisgroundorfloormountedandisbelowthe

levelofthecollectors;acirculatingpumpmoveswaterorheattransferfluid

betweenthetankandthecollectors.

SWHsystemsaredesignedtodelivertheoptimumamountofhotwaterformostof

theyear.However,inwintertheresometimesmaynotbesufficientsolarheatgain

todeliversufficienthotwater.Inthiscaseagasorelectricboosterisnormally

usedtoheatthewater.


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Page |8Hotwaterheatedbythesunisusedinmanyways.Whileperhapsbestknownina

residentialsettingtoprovidehotdomesticwater,solarhotwateralsohasindustrial

applications,e.g.togenerateelectricity.[1]Designssuitableforhotclimatescanbe

muchsimplerandcheaper,andcanbeconsideredanappropriate technologyfor

theseplaces.TheglobalsolarthermalmarketisdominatedbyChina,Europe,

JapanandIndia.

Inordertoheatwaterusingsolarenergy,acollector,oftenfastenedtoaroofora

wallfacingthesun,heatsworking fluidthatiseitherpumped(activesystem)or

drivenbynatural convection(passivesystem)throughit.Thecollectorcouldbe

madeofasimpleglasstoppedinsulatedboxwithaflatsolarabsorbermadeof

sheetmetalattachedtocopperpipesandpaintedblack,orasetofmetaltubes

surroundedbyanevacuated(nearvacuum)glasscylinder.Inindustrialcasesa

parabolicmirrorcanconcentratesunlightonthetube.Heatisstoredinahotwater

storagetank.Thevolumeofthistankneedstobelargerwithsolarheatingsystems

inordertoallowforbadweather,andbecausetheoptimumfinaltemperaturefor

thesolarcollectorislowerthanatypicalimmersionorcombustionheater.The

heattransferfluid(HTF)fortheabsorbermaybethehotwaterfromthetank,but

morecommonly(atleastinactivesystems)isaseparateloopoffluid

containinganti-freezeandacorrosion inhibitorwhichdeliversheattothetank

throughaheat exchanger(commonlyacoilofcoppertubingwithinthetank).

Anotherlower-maintenanceconceptisthe'drain-back':noanti-freezeisrequired;

insteadallthepipingisslopedtocausewatertodrainbacktothetank.Thetankis

notpressurizedandisopentoatmosphericpressure.Assoonasthepumpshuts

off,flowreversesandthepipesareemptybeforefreezingcouldoccur.


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Page |9Residentialsolarthermalinstallationsfallintotwogroups:passive(sometimes

called"compact")andactive(sometimescalled"pumped")systems.Bothtypically

includeanauxiliaryenergysource(electricheatingelementorconnectiontoagas

orfueloilcentralheatingsystem)thatisactivatedwhenthewaterinthetankfalls

belowaminimumtemperaturesettingsuchas55C.Hence,hotwaterisalways

available.Thecombinationofsolarwaterheatingandusingtheback-upheatfrom

awoodstovechimneytoheatwater[2]canenableahotwatersystemtoworkall

yearroundincoolerclimates,withoutthesupplementalheatrequirementofasolar

waterheatingsystembeingmetwithfossilfuelsorelectricity.

Whenasolarwaterheatingandhot-watercentralheatingsystemareusedin

conjunction,solarheatwilleitherbeconcentratedinapre-heatingtankthatfeeds

intothetankheatedbythecentral heating,orthesolarheatexchangerwillreplace

thelowerheatingelementandtheupperelementwillremaininplacetoprovide

foranyheatingthatsolarcannotprovide.However,theprimaryneedforcentral

heatingisatnightandinwinterwhensolargainislower.Therefore,solarwater

heatingforwashingandbathingisoftenabetterapplicationthancentralheating

becausesupplyanddemandarebettermatched.Inmanyclimates,asolarhotwater

systemcanprovideupto85%ofdomestichotwaterenergy.Thiscaninclude

domesticnon-electricconcentrating solar thermalsystems.Inmanynorthern

Europeancountries,combinedhotwaterandspaceheatingsystems(solar

combisystems)areusedtoprovide15to25%ofhomeheatingenergy.


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Page |10

FIG-1:solar water heater

SOLAR TOWER

Asolartower,inthecontextofastronomy,isastructureusedtosupportequipmentforstudyingthesun,andistypicallypartofsolartelescopedesigns.

Generically,thetermsolartowerhasmanymoreusesespeciallyforatypeof

powerproductionusingEarth'sSun.Solartowerobservatoriesarealsocalled

vacuumtowertelescopes.

Solartowersareusedtoraisetheobservationequipmentabovetheatmospheric

disturbancescausedbysolarheatingofthegroundandtheradiationoftheheat


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Page |11intotheatmosphere.Traditionalobservatoriesdonothavetobeplacedhighabove

groundlevel,astheydomostoftheirobservationatnight,whengroundradiation

isataminimum.

ThehorizontalSnowsolarobservatorywasbuiltonMountWilsonin1904.Itwas

soonfoundthatheatradiationwasdisruptingobservations.Almostassoonasthe

SnowObservatoryopened,planswerestartedfora60-foot-tall(18m)towerthat

openedin1908followedbya150-foot(46m)towerin1912.The60-foot(18m)

toweriscurrentlyusedtostudyhelioseismology,whilethe150-foot(46m)tower

isactiveinUCLA'sSolarCycleProgram.

Thetermhasalsobeenusedtorefertootherstructuresusedforexperimental

purposes,suchastheSolarTowerAtmosphericCherenkovEffectExperiment

(STACEE),whichisbeingusedtostudyCherenkovradiation,andtheWeizmann

Institutesolarpowertower.

FIG-2:solartower


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Solar panel

Asolarpanel(photovoltaicmoduleorphotovoltaicpanel)isapackagedinterconnectedassemblyofsolarcells,alsoknownasphotovoltaiccells.Thesolar

panelcanbeusedasacomponentofalargerphotovoltaicsystemtogenerateand

supplyelectricityincommercialandresidentialapplications.

Becauseasinglesolarpanelcanonlyproducealimitedamountofpower,many

installationscontainseveralpanels.Aphotovoltaicsystemtypicallyincludesan

arrayofsolarpanels,aninverter,maycontainabatteryandinterconnectionwiring.

Solarpanelsuselightenergy(photons)fromthesuntogenerateelectricitythrough

thephotovoltaic effect.Thestructural(loadcarrying)memberofamodulecan

eitherbethetoplayerorthebacklayer.Themajorityofmodulesusewafer-

basedcrystalline siliconcellsorthin-film cellsbasedoncadmium

tellurideorsilicon.Theconductingwiresthattakethecurrentoffthepanelsmay

containsilver,copperorotherconductive(butgenerallynotmagnetic)transition

metals.

Thecellsmustbeconnectedelectricallytooneanotherandtotherestofthe

system.Cellsmustalsobeprotectedfrommechanicaldamageandmoisture.Most

solarpanelsarerigid,butsemi-flexibleonesareavailable,basedonthin-filmcells.

Electricalconnectionsaremadein seriestoachieveadesiredoutputvoltage

and/orin paralleltoprovideadesiredcurrentcapability.

Separatediodesmaybeneededtoavoidreversecurrents,incaseofpartialortotal

shading,andatnight.Thep-n junctionsofmono-crystallinesiliconcellsmayhave

adequatereversecurrentcharacteristicsthatthesearenotnecessary.Reverse


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Page |13currentswastepowerandcanalsoleadtooverheatingofshadedcells.Solarcells

becomelessefficientathighertemperaturesandinstallerstrytoprovidegood

ventilationbehindsolarpanels.[1]

Somerecentsolarpaneldesignsincludeconcentratorsinwhichlightisfocused

bylensesormirrorsontoanarrayofsmallercells.Thisenablestheuseofcells

withahighcostperunitarea(suchasgallium arsenide)inacost-effective

way.[citation needed]

Dependingonconstruction,photovoltaicpanelscanproduceelectricityfroma

rangeoffrequencies of light,

but

usually

cannot

cover

the

entire

solar

range

(specifically,ultraviolet,infraredandlowordiffused light).Hencemuchofthe

incidentsunlightenergyiswastedbysolarpanels,andtheycangivefarhigher

efficienciesifilluminatedwithmonochromaticlight.Thereforeanotherdesign

conceptistosplitthelightintodifferentwavelengthrangesanddirectthebeams

ontodifferentcellstunedtothoseranges.[2]Thishasbeenprojectedtobecapable

ofraisingefficiencyby50%.Theuseofinfrared photovoltaic cellshasalsobeen

proposedtoincreaseefficiencies,andperhapsproducepoweratnight.[citation needed]

Sunlight conversion rates(solarpanelefficiencies)canvaryfrom5-18%in

commercialproducts,typicallylowerthantheefficienciesoftheircellsin

isolation.Panelswithconversionratesaround18%areindevelopment

incorporatinginnovationssuchaspowergenerationonthefrontandback

sides.[citation needed]TheEnergy Densityofasolarpanelistheefficiencydescribedin

termsofpeakpoweroutputperunitofsurfacearea,commonlyexpressedinunits

ofWattspersquarefoot(W/ft2).Themostefficientmass-producedsolarpanels

haveenergydensityvaluesofgreaterthan13W/ft2.


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FIG-3:solar panel

EnergystoragemethodsSolarenergyisnotavailableatnight,andenergystorageisanimportantissue

becausemodernenergysystemsusuallyassumecontinuousavailabilityof

energy.[96]

Thermalmasssystemscanstoresolarenergyintheformofheatatdomestically

usefultemperaturesfordailyorseasonal durations.Thermalstoragesystems

generallyusereadilyavailablematerialswithhighspecific heatcapacitiessuchas

water,earthandstone.Well-designedsystemscanlowerpeak demand,shifttime-

of-usetooff-peakhoursandreduceoverallheatingandcoolingrequirements.[97][98]


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Page |15Phasechangematerialssuchasparaffin waxandGlauber's saltareanotherthermal

storagemedia.Thesematerialsareinexpensive,readilyavailable,andcandeliver

domesticallyusefultemperatures(approximately64C).The"DoverHouse"

(inDover, Massachusetts)wasthefirsttouseaGlauber'ssaltheatingsystem,in

1948.[99]

Solarenergycanbestoredathightemperaturesusingmolten salts.Saltsarean

effectivestoragemediumbecausetheyarelow-cost,haveahighspecificheat

capacityandcandeliverheatattemperaturescompatiblewithconventionalpower

systems.TheSolar Twousedthismethodofenergystorage,allowingittostore

1.44TJinits68m3storagetankwithanannualstorageefficiencyofabout

99%.[100]

Off-gridPVsystemshavetraditionallyusedrechargeable batteriestostoreexcess

electricity.Withgrid-tiedsystems,excesselectricitycanbesenttothe

transmissiongrid,whilestandardgridelectricitycanbeusedtomeet

shortfalls.Net meteringprogramsgivehouseholdsystemsacreditforany

electricitytheydelivertothegrid.Thisisoftenlegallyhandledby'rollingback'the

meterwheneverthehomeproducesmoreelectricitythanitconsumes.Ifthenet

electricityuseisbelowzero,theutilityisrequiredtopayfortheextraatthesame

rateastheychargeconsumers.[101]Otherlegalapproachesinvolvetheuseoftwo

meters,tomeasureelectricityconsumedvs.electricityproduced.Thisisless

commonduetotheincreasedinstallationcostofthesecondmeter.

Pumped-storage hydroelectricitystoresenergyintheformofwaterpumpedwhen

energyisavailablefromalowerelevationreservoirtoahigherelevationone.The

energyisrecoveredwhendemandishighbyreleasingthewatertorunthrougha

hydroelectricpowergenerator


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5.ADVANTAGES1.SOLARENERGYISARENEWABLERESOURCEYouwillneverrunoutofsolarenergy.Sure,thesunsetsatnight,andon

thosedarkandgloomydaysitmaynotalwaysbevisible,butyoucanbe

surethatitwillreturn.Oil,ontheotherhand,islimited,andonceyourun

out,itisgoneforever.Althoughtheamountofpowerthesuncangenerate

islimitedtotheamountofsunlightyouget,itispossibleto

generateelectricityevenoncloudydays.

2.SOLARPOWERISNON-POLLUTINGUnlikeoil,solarpowerdoesnotemitanysortoftoxicgasesintotheenvironment.Itisacompletelyenvironmentallyfriendlyapproachto

generatingelectricity.Thereisevenworkbeingdonetomaketherecycling

ofsolarpanelsmoreeffective.

3.LIGHTFROMTHESUNISFREEAftertheinitialcostsinvolvedinsettingupthesolarpanelsandsolarlights

etc,youwillneverhavetopaytorunthem.

4.SOLARPOWERISQUITEFLEXIBLEYoucanhaveanarrayofsolarpanelsonyourrooftogeneratepowerfrom

yourhome.Youcanalsohavesmallersolarcellsongardenlightsor

anythingelseoutsidethatonlyneedsasmallamountofelectricity.Not

havingtorunawirecanbeahugetimesaver.

5.SOLARCELLSREQUIREMINIMALMAINTENANCEOncethesolarcellsaresetup,theyrequireverylittlemaintenance,mainly


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Page |17becausetherearenomovingpartsthathavetobemaintained.Solarcellscanlastalifetimeandisveryeasytoinstall.

6.SOLARPOWERISSILENTThemethodsthatareusedtofindandextractoilareverynoisy.Evenwind

powercancreatealotofnoise.Solarpoweriscompletelysilent.

7.SOLARENERGYCANSAVEMONEYINTHELONGRUNSolarenergyhasmanyadvantages,someofthemnotascommonas

others.Themainreasonforthisperhapsisthattheinitialcostisquitehigh.

However,youcansaveasignificantamountofmoneyusingsolarpower,

whichcomparesfavorablytopayinganelectricitybillattheendofthe

month.Thereisalotofworkthathasbeendonetomakesolarpowermore

accessibletothecommonman,withresearchersfindingwaysandmeans

tomakethisresourceacommonpractice.Solarpowerisindeedan

amazing,naturalenergyresourcewithsomuchpotentialtobetappedinto.

Itisjustamatteroftimebeforesolarpowerbecomesaglobalhit.

THEAPPLICATIONSAREASFOLLOWSRURALELECTRIFICATIONTheprovisionofelectricitytoruralareasderivesimportantsocialand

economicbenefitstoremotecommunitiesthroughouttheworld.Power

supplytoremotehousesorvillages,electrificationofthehealthcare

facilities,irrigationandwatersupplyandtreatmentarejustfewexamplesof

suchapplications.

1.WATERPUMPING:Solarpumpsareusedprincipallyfortwoapplications:villagewatersupply

(includinglivestockwatering),andirrigation.Sincevillagesneedasteady

supplyofwater,provisionhastobemadeforwaterstorageforperiodsof

lowinsolation.Incontrast,cropshavevariablewaterrequirementsduring

theyearwhichcanoftenbemetbysupplyingwaterdirectlytoproduce

withouttheneedforastoragetank.

2.LIGHTENING:


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Page |18Intermsofthenumberofinstallations,lightingispresentlythebiggestapplicationofphoto-voltaic,withtensofthousandsofunitsinstalledworld-

wide.Theyaremainlyusedtoprovidelightingfordomesticorcommunity

buildings,suchasschoolsorhealthcenters.PVisalsobeingincreasingly

usedforlightingstreetsandtunnels,andforsecuritylighting.

PROFESSIONALAPPLICATIONSForsometime,photovoltaicmoduleshaveprovedtobeagoodsourceof

powerforhigh-reliabilityremoteindustrialuseininaccessiblelocations,or

wherethesmallamountofpowerrequiredismoreeconomicallymetfroma

stand-alonePVsystemthanfrommainselectricity.Examplesofthese

applicationsinclude:

1.OCEANNAVIGATIONAIDS:Manylighthousesandmostbuoysarenowpoweredbysolarcells.

2.TELECOMMUNICATION SYSTEMS:radiotransceiversonmountaintopsortelephoneboxesinthecountrycanoftenbesolarpowered.

3.REMOTEMONITORINGANDCONTROL:scientificresearchstations,seismicrecording,weatherstations,etc.useverylittlepowerwhich,in

combinationwithadependablebattery,isprovidedreliablybyasmallPV

module.

4.CATHODICPROTECTION:thisisamethodforshieldingmetalworkfromcorrosion,forexample,pipelinesandothermetalstructures.APV

systemiswellsuitedtothisapplicationsinceaDCsourceofpoweris

requiredinremotelocationsalongthepathofapipeline.

GRIDCONNECTEDSYSTEMSTwotypesofgrid-connectedinstallationsareusuallydistinguished,

centralizedPVpowerstations,anddistributedgenerationinunitslocated

directlyatthecustomer'spremises(PVinbuildings).


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1.PVPOWERStations:APVpowerstationfeedsthegeneratedpowerinstantaneously intotheutilitydistributionnetwork(the'grid')bymeansofoneormoreinvertersandtransformers.PVpowerstationsmaybeapproachingeconomicviabilityinlocationswheretheyassistthelocalgridduringperiodsofpeakdemand,andobviatetheneedtoconstructanewpowerstation.Thisisknownaspeakshaving.ItcanalsobecheapertoplacesmallPVplantswithinthetransmissionsystemratherthantoupgradeit('embedded'generation).

2.PVInBuildings:PVarraysmountedonrooftopsorfacadesofferthepossibilityoflarge-scalepowergenerationindecentralizedmedium-sizedgrid-connected

units.

ThemainadvantagesofthesedistributedsystemsoverlargePVplantsareasfollows:Therearenocostsinbuyingthelandandpreparingthesite.Thetransmissionlossesaremuchlowerbecausetheloadisonthesamesiteasthesupply.ThevalueofthePVelectricityisalsohigherbecauseitisequaltothesellingpriceofthegridelectricitywhichhasbeenreplaced,ratherthattothecostofgeneratingit.

Disadvantages:

Oneofthemaindisadvantagesistheinitialcostoftheequipmentusedtoharnessthesunsenergy.Solarenergytechnologiesstillremainacostlyalternativetotheuseofreadilyavailablefossilfueltechnologies.Asthepriceofsolar panelsdecreases,wearelikelytoseeanincreaseintheuseofsolarcellstogenerateelectricity.


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Asolarenergyinstallationrequiresalargeareaforthesystemtobeefficientinprovidingasourceofelectricity.Thismaybeadisadvantageinareaswherespaceisshort,orexpensive(suchasinnercities).Pollutioncanbeadisadvantagetosolarpanels,aspollutioncandegradetheefficiencyofphotovoltaiccells.Cloudsalsoprovidethesameeffect,astheycanreducetheenergyofthesunsrays.Thiscertaindisadvantageismoreofanissuewitholdersolarcomponents,asnewerdesignsintegratetechnologiestoovercometheworstoftheseeffects.Solarenergyisonlyusefulwhenthesunisshining.Duringthenight,yourexpensivesolarequipmentwillbeuseless,howevertheuseofsolarbatterychargerscanhelptoreducetheeffectsofthisdisadvantage.

Thelocationofsolarpanelscanaffectperformance,duetopossibleobstructionsfromthesurroundingbuildingsorlandscape.

SolarConversionEfficiency hesolarconversionefficiencyofasolarcelloraphotovoltaiccellis

determinedbyhowmuchofthesunlightthecellisabletoconvertintoelectricalenergy.Inotherwords,theproportionofthetotallightenergythataphotovoltaiccellisabletoconvertintousableelectricityisthesolarconversionefficiencyofthatparticulartypeofPVcell.ItisonthebasisofthesolarconversionefficiencyofacellandthecostofitsproductionthataPVcellisjudgedandranked.Thereasonwhyitissoimportantthatthesolarconversionefficiencyissignificantlyhigherthanpreviousgenerationsisduetothefactthatitisanalternativesourceofpowerthatwasinventedmainlytoreducethepressureofffromnon-renewablesourcesofenergy.


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Inordertosuccessfullydothat,thesolarcellsneedtoprovideahighsolarconversionratio,sothatenergycanattimesreplacetheuseofoilandcoal.Therearefourmaintypesofphotovoltaiccellsthatareusuallyusedinhouseholdsandbelowarethenameswithalittledetailandinfoabouteachofthem.AmorphousSiliconPVCellsThesecellsarenotconstructedwithcrystallinesilicon,buttheyhaveathinsiliconfilmonthetopofthemetallicsemiconductor(coppermainly).Theoneadvantagethattheamorphoussiliconpanelshaveoversomeoftheothersisthattheircheaperproductioncostsmakethemmoreaffordable.However,sincetheirsolarconversionefficiencyisaslowas5%or6%,theymaynotbeidealifyouarelookingforbenefitinthelongrun.PolycrystallineSiliconPVCellsAlsoknownasmulti-crystallinesiliconPVcells,thesePVcellshavemetalconductorsattachedtotheirsidestostayincontactwiththeothercellsinapanelandalsotofacilitateelectronmovement.ThePolycrystallinepanelshaveasolarefficiencyratethatcanbeanythinginbetween12%to14%andalso,theycanbethecheapestsolarpanelsthatonecanbuy.Apartfrombeingcheap,itisalsoeasiertoreplaceanindividualcellinapanelthatconsistsofmanyPVcells,thusmakingthepolycrystallinesolarpanelsoneofthebestpanelstoinstall.StrongRibbonSiliconPVCellsThesesolarcellsarequitesimilarwhencomparedtothepolycrystallinepanelsasfarastheenergyefficiencyratesareconcerned;infact,theyareevensimilarinthewaythattheyaremanufactured.Theyarehowever,evencheaperthanthepolycrystallinepanelsbecausethesecellsareconstructedoutofstripsofsiliconandmetalconnectorsinsteadofbeingconstructedpurelyoutofsilicon.MonocrystallineSiliconPVCellsThemonocrystallinepanelconsistsofonesinglesheetofsiliconwithmetalsattachedtothesidesofthesheetonlyinordertofurtherfacilitateelectronmovement.Withsolarconversionefficiencyratesashighas18%,monocrystallinesiliconsolarcellsorpanelsarethemosteffectiveindoingthejob,butarealsothemostexpensiveamongthefour.However,ifonemanagestolookpasttheinitialsetupcosts,itcansavealotofmoneyinthelongrun.


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ELECTRICPOWERGENERATIONINSPACEPhotovoltaicsolargeneratorshavebeenandwillremainthebestchoicefor

providingelectricalpowertosatellitesinanorbitaroundtheEarth.Indeed,

theuseofsolarcellsontheU.S.satelliteVanguardIin1958demonstrated

beyonddoubtthefirstpracticalapplicationofphotovoltaics.Sincethen,the

satellitepowerrequirementshaveevolvedfromfewWattstoseveral

kilowatts,witharraysapproaching100kWbeingplannedforafuturespace

station.

Aspacesolararraymustbeextremelyreliableintheadverseconditionsof

spaceenvironment.Sinceitisveryexpensivetolifteverykilogramof

weightintotheorbit,thespacearrayshouldalsohaveahighpower-to-

weightratio.

RESULTS

1.Wecanhavepollutionlessworld.

2.Avoidthescarcityoffossilfuels.

3.Abundantelectricityforallpurposes.

4.Supplypowerindeserts,oceans,andtoremoteareas.

5.Supplyofsufficientpowertoearthorbitingsatellitesandspaceprobes.


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7.CONCLUSIONSolarcellsarelonglastingsourcesofenergywhichcanbeusedalmost

anywhereparticularlyusefulwherethereisnonationalgridandalsowhere

therearenopeoplesuchasremotesitewaterpumpingorinspace,

providecosteffectivesolutionstoenergyproblemsinplaceswherethereis

nomainselectricity.Moreovertheyaretotallysilentandnon-polluting.They

havenomovingpartstheyrequirelittlemaintenanceandhavealong

lifetimewhencomparedtootherrenewablesourcestheyalsopossess

manyadvantages;windandwaterpowerrelyonturbineswhicharenoisy,

expensiveandliabletobreakingdown.Wearelivinginasocietywhere

thereisatremendouspollution,withthescarcityoffossilfuelsandresources.Toovercomethoseproblemsweneedtochangeourlifestyles.

Sincethesolarenergyisabundantandisfreeofcost,wecanutilizethe

solarpowertogivearebirthtomankind.

8.BIBLIOGRAPHY

1.http://www.wikipedia.org

2.Google.com

3.PrinciplesofelectronicsbySze4.http://www.greenblog.com

seminar report on electronics

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