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Re:Solar PV rapidly becoming the cheapest option to generate... by droithomme on Tuesday October 25, 2011 @12:14AM (#3152788)
Thanks. Ok, your peak equivalent hours number for Portland OR using a fixed position is 4, implying an average of 365 * 4 * 4.5k = 6570kWh/year, correct?

The federal DOE site calculator for the same 4.5kWh fixed tilt plant gives 4580 kWh/yr for Portland (http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/US/...), ranging from 142 kWh/mo in December to 578kWh/mo in July. What accounts for the discrepancy between the two calculations?

Re:Solar PV rapidly becoming the cheapest option to generate... by bzbarsky on Tuesday October 25, 2011 @11:49AM (#3154459)
A good bit of the discrepancy is that the calculator assumes that the DC to AC conversion is only 77% efficient (see "DC to AC Derate Factor" in the calculator), while the naive calculation assumes 100% efficiency of conversion, right?