b'reenRoofingUpdate Integrating Photovoltaics Onto Building Envelope Surfaces By Michael Gumm Introductionor posts.lated crys Thi:n-Fihn PVs Glass-encapsuOver much of the past 30 years,talline silicon is the most com A number of new PV techmonnologe thestandardforsolar technologytype of solar module.Most rack gies have begun to emer in the installedonbuildingshasbeenmountedPVmodulesc istofmarketplace.T n techons heseewer rack-mounted,siliconcrystal I crystalline silicon, either as anologies, calledthin-film photoine single based solar panels. Today,aworasa polycrystallinewafer,tovoltaics, include very thin lay of ne ers type of technology called thin-filmgenerateph o activematerial electricity.ot voltaically otovoltaicsmetal, ph is ready to change theSilicon-basedPVshavetheplacedon glass, flexibleor way solar collectors are installed onhighest electricalou ut of anyplasticsubstrates.Flexiblethintpbu This paper gives aPV material per sq ft.film PVmodules a madeby ildings.broadre overview ofboththeold and the T lp p tionisdep ingsemiconductor materiypica owerroduc ositnewsolartechnologies,plusbetween 12 and 18per sq ft.als on stainless steel foil or a wattsplasingVs insight on design and installingSiliconwaferP aremoretic carrier and encapsulating them Photovoltaics (PVs)photovoltaicexpensiveandrequirelargewitha solartransparentplastic systems. AccordingtotheSolarEnergyamounts of energy to manpolymer. Semicondu materials ufac ctor are one ofmostIndustryAssociation, solar powerture.used in thin-filminclude: thePVs in 2006 represented only one-tenth Silicon modu cost,on averAmorphous silicon (a-Si):Unipromising sustainableles1 of one percent of the added electri age, $4.85 per watt. Solar,e ,XuPow rfilm andnlight renewable energycalpowercapacitytotheU.S. Solid silicon PV modules repreCopperindiumgallium dise-(0technologies.power grid.Inthree years,solarsent95%ofallsolarpanelslenide(GIGS):Miasole, couldgrow to 10 percentofnewinstalled.Nan and Global Solar oSolar, addedelectricalcapacity;and,byOtherbuildingsystem applicaCadmium tellu dee First ri (CdT ): 2018,solarisexpectedtocon tionsinclude semitransparentPVSolar tribute 50 percent of the annual U.S.glassmodulesforwindowsandOther new solar technologies in silicon. power increase.skylights using crystallinedevelopmentincludedye-sensiSeveralPVmanufacturershavetizedsolarcellsusingadyePhotovoltaic (PV) Basicsalsointegratednon-glass,poly im layer of titanium d pregnatedioxPhotovoltaics (PVs)areoneofmer-surfacedcrystallinemodulesidetogenerateelectricity. themostpromisingsustainableinto new roofingL Dye-sensitizedsolare Isare products.eadingel renewableenergytechnologies.siliconpanelm r printed onto various polymer films anufactu ers Solar (PV) modules produce elec includeSuntech,ET Solar, Sun withequipmentresembling Sc puter tricity on site, directly from the sunPower,hott Solar, Sharp Corpo com printers. Recently, new andwiththeleastenviron ration, and Canon Inc. (See Figurecarbon-based (or solar modmentalganic) harm. Solar has the smallest envi 1.)uleshavebeendeveloped. ronmentalimpactofanyoftheContinued on page 8 renewableenergysystems.PV modulesaresolid-statedevices thatsimplymakeelectricityfrom sunlight. Solar requires little maintenance,producesnopollution, anddoesnot deplete anynonrenewablefossienergyresources, I such as oil, natural gas, and coal. Crystalline Silicon We are all familiar with the basic Figure 1 -Crystalline-silicon arraya Vo heesville,school. Photo courte of PV glass module mounted on racksonor NY,syNew rg ResearchDe pme AuYour State Ene y&velo ntthority. 7'