These solar resources can help solar installers and commercial, government and industrial solar customers learn more about their needs and the benefits of using photovoltaic energy. Note that links open in a new window.
Database of Renewable Energy and Energy Efficiency State Incentives
U.S Department of Energy Energy Efficiency Information
Solar Programs and Initiatives from the U.S. Department of Energy
Insolation measures the amount of solar enrgy available in a given area in a given time. For industrial, commercial and residential solar power systems, insolation is commonly measured as kwh/(kwp*y), or kilowatt hours per year per kilowatt peak rating.
These are general measurements, as the solar constant varies with the Earth-Sun distance and solar cycles. Factors that affect insolation include the time of day (length of light's path through the atmosphere based on solar elevation angle), cloud cover, relative humidity and the presence of airborne impurities, such as ash and smog.
The map below provides estimates of insolation for the United States. For insolation estimates outside of this area, please use our Global Insolation Map (pdf). For additional information on determining the estimated solar hours in a given area, please contact us.