Solarphotovoltaicthermalenergysystems,orPVTs,generatebothheatandelectricity,butuntilnowtheyhaven’tbeenverygoodattheheat-generatingpartcomparedtoastand-alonesolarthermalcollector.That’sbecausetheyoperateatlowtemperaturestocoolcrystallinesiliconsolarcells,whichletsthesilicongeneratemoreelectricity_butisn’taveryefficientwaytogatherheat.That’saproblemofeconomics.Goodsolarhot-watersystemscanharvestmuchmoreenergythanasolar-electricsystematasubstantiallylowercost_.Andit，salsoaspaceproblem：photovoltaiccellscantakeupallthespaceontheroof,leavinglittleroomforthermalapplications.Inapairofstudies,JoshuaPearce,anassociateprofessorofmaterialsscienceandengineering,hasdevisedasolutionintheformofabetterPVTmadewithadifferentkindofsilicon.HisresearchcollaboratorsareKunalGirotrafromThinSiliconinCaliforniaandMichaelPathakandStephenHarrisonfromQueen’sUniversity,Canada."Mostsolarpanelsaremadewithcrystallinesilicon，butyoucanalsomakesolarcellsoutofamorphoussilicon,commonlyknownasthin-filmsilicon.Theydon’tcreateasmuchelectricity,buttheyarelighter,flexible,andcheaper.And,becausetheyrequire_muchlesssilicon,theyhaveagreenerfootprint.Unfortunately，thin-filmsiliconsolarcellsarevulnerabletosomebad-newsphysicsintheformoftheStaebler-Wronskieffect.“Thatmeansthattheirefficiencydrops_whenyouexposethemtolight—prettymuchtheworstpossibleeffectforasolarcell,”Pearceexplains，whichisoneofthereasons_thin-filmsolarpanelsmakeuponlyasmallfractionofthemarket.However,PearceandhisteamfoundawaytoengineeraroundtheStaebler-Wronskieffectbyincorporatingthin-filmsiliconinanew_type_ofPVT.Youdon’thavetocooldownthin-filmsilicontomakeitwork.Infact，Pearce’sgroupdiscoveredthatbyheatingittosolar-thermaloperatingtemperatures，neartheboilingpoint_ofwater,theycouldmakethickercellsthatlargely_overcame_theStaebler-Wronskieffect.Whentheyappliedthethin-filmsilicondirectlytoasolarthermalenergy_collector,theyalsofoundthatbybakingthecellonceaday，theyboosted_thesolarcell’selectricalefficiencybyover10percent.