What's a home with panels on top worth to you?

With few studies having tackled this question, research unveiled today by the U.S. Energy Department's Lawrence Berkeley National Laboratory found that people willingly paid more for homes with photovoltaic. Using data from 72,000 California homes from 2000 to mid-20009, houses with PV sold for a premium "expressed in dollars per watt of installed PV, of approximately $3.90 to $6.40 per watt."

Taking an average California home at $500,000, that can be an increase of about $17,000 for a 3,100-watt system, according to the study. "So we're looking at a 3-3.5 percent bump," in the value of a home with a PV system, the study's lead author Ben Hoen told me today by phone. "This premium is pretty similar to the installment costs" of a PV system. But the older the PV system, the lower the premium, the study found.

"The study shows that solar can be a solid investment for homeowners and a revenue generator for homebuilders," Tom Kimbis of Solar Energy Industry Association told Bloomberg.

However, homes with panels that are leased from a third party are a "non-starter," said Hoen, who added that solar leasing is an element that was not considered in their research.

California, which leads the country in solar, recently set a renewable goal of 33 percent by 2020. The state is inching near 100,000 individually installed PV systems -- "more than 90 percent of which are residential," according to the Lawrence Lab.

-- Brian Foley/photo courtesy Zan Dubin Scott.