Relatively little research exists estimating the marginal impacts of photovoltaic (PV) energy systems on home sale prices. Using a large data set of California homes that sold from 2000 through mid-2009, we find strong evidence, despite a variety of robustness checks, that existing homes with PV systems sold for a premium over comparable homes without PV systems, implying a near full return on investment. Premiums for new homes are found to be considerably lower than those for existing homes, implying, potentially, a trade-off between price and sales velocity. The results have significant implications for homeowners, builders, appraisers, lenders, and policymakers. (JEL R31, D12, C33)