Joel: I have noticed that the energy predicted by the CSI calculator is consistently lower than the first year output of our systems, usually by at least 10% to 20%. This is also true of the PVWatts version we use. At first we thought that we had done such a great job! But I believe that the accumulative conservative default values in both calculators and the expectation for module degradation built in to the source code is the real answer. If our customers ever have an issue with understanding lower production, it is usually because they fail to recognize that daily or monthly production values relate to annual production expectations on a non-linear basis. Recently El Nino has dramatically affected generation and as well, our own production schedule. Kicked out butts, in fact. Pat Redgate Ameco Solar In a message dated 4/25/2010 9:43:09 A.M. Pacific Daylight Time, joel.david...@sbcglobal.net writes: Wrenches,
With the Iceland volcano in the news and winter over, I thought it would be a good time ask wrenches convince their customers that their reduced solar production was caused by atmospheric conditions and not their PV system. I'm not talking about short-term conditions like a few cloudy days. I mean when you install a PV system in October and have to explain in gloomy February why their PV system is not performing like you predicted. Missing the mark can be bad for business. For example, reduced insolation caused by the El Chichon Mexico volcano was reportedly one of the reasons that the Luz solar power plants went bankrupt in the 1980s. See http://en.wikipedia.org/wiki/Solar_Energy_Generating_Systems and http://www.unige.ch/cuepe/html/biblio/pdf/michalsky-ineichen%201993%20-%20mo unt%20pinatubo%20and%20solar%20power%20plants%20(solar%20today).pdf 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
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