Minor Memo: The median price for a rooftop solar system installed in the United States in 2011 was $6.13 a watt for residential and small commercial systems of 10 kilowatts or less, and $4.87 a watt for commercial systems larger than 100 kilowatts, according to a report by the US Department of Energy in November. The average cost for utility-scale solar photovoltaic projects was $3.42 a watt. Prices are falling at an accelerating rate. Prices declined 5% to 7% a year from 1998 through 2011, but at an 11% to 14% rate in the last year of that period and may have fallen by as much as 25% to 29% if one compares Q4 2010 to Q4 2011 prices. According to the Department of Energy, analysts expect global average module prices to be almost 50% lower in 2013 than in 2011: 74¢ a watt compared to $1.37 a watt in 2011. The department said there are no analyst projections for the balance of system costs. The report is called “Photovoltaic (PV) Pricing Trends: Historical, Recent, and Near-Term Projections.”

by Keith Martin