EnviroAtlas, Average Annual Daily Solar Energy Potential, per 12-digit HUC, California

The average daily potential watt hours of solar energy were estimated from maps produced by the National Renewable Energy Laboratory (NREL) for the U.S. Department of Energy (February 2009). The original data was from a 10km, satellite modeled dataset representing data from 1998–2005. The 10km data was converted to 30m grid cells, and zonal statistics were estimated for a final value of average kWh/m2/day for each 12-digit HUC. The insolation values represent the resource available to a flat plate collector, such as a photovoltaic panel, oriented due south at an angle from horizontal equal to the latitude of the collector location. For more information about the original dataset, refer to the National Renewable Energy Laboratory (NREL) website.