California Solar Center Huge non-profit source of information about all things photovoltaic. Highly recommended!   Go Solar California  - Umbrella site for solar programs in California. For example, from this site you can learn about the California Solar Initiative.   Renewable Energy Program run by the CSI. Describes the rebate program and more!   Sandia Laboratories photovoltaic web site - they do lots of research and offer lots of free materials.   National Renewable Energy Labs (NREL) - The U.S. Department of Energy's premier laboratory for renewable energy research & development and a lead lab for energy efficiency R&D   NREL Renewable Resource Data Center. Info about all types of renewable energy: solar, wind, hydro, biomass, and more!