Joel and All, PV:WATTS is just a very simple simulation. You can make simple corrections for temp coefficient if you like, but if you want better accuracy, you have to go to a more sophisticated program like PVSyst or PVSol.
Bill. -----Original Message----- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Joel Davidson Sent: Monday, April 19, 2010 9:03 PM To: RE-wrenches Subject: Re: [RE-wrenches] PVWatts Module Temperature Coefficient Dave, Thank you. PVWatts does not predict accurately Unisolar (-0.21%/degC) or Sunpower (-0.38%/degC) or Sanyo HIT ( -0.336%/degC). In Los Angeles, I measured 6% more annual kWh from Unisolar over a 3 year period and over 10% more from Sunpower so far this year. Joel Davidson ----- Original Message ----- From: "Dave Click" <davecl...@fsec.ucf.edu> To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org> Sent: Monday, April 19, 2010 7:01 AM Subject: Re: [RE-wrenches] PVWatts Module Temperature Coefficient (was Enphase derate) > It seems to be -0.5%/degC: > http://rredc.nrel.gov/solar/calculators/PVWATTS/moreabout.html > > > -------- Original Message -------- > Subject: [RE-wrenches] PVWatts Module Temperature Coefficient (was Enphase > derate) > From: Joel Davidson <joel.david...@sbcglobal.net> > To: RE-wrenches <re-wrenches@lists.re-wrenches.org> > Date: 2010/4/18 12:23 > >> Wrenches, >> PVWatts does not accurately predicate Unisolar and Sunpower module >> performance because it uses a generic single crystal silicon solar >> module power temperature coefficient (I think -0.4% per degree C). Does >> someone have the technical paper that specifies PVWatts module >> temperature coefficient? Thank you. >> Joel Davidson >> >> _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
