The service from the U.S. National Renewable Energy Laboratory (NREL) provides access to a database of solar radiation available at locations within the United States. The National Solar Radiation Database (NSRDB) lists recorded solar energy readings from a wide range of weather stations. Data are summarized based on readings captured 1991-2005 using the Typical Meteorological Year (TMY) methodology.
API methods support search for solar radiation data for a location specified by latitude and longitude. Results can be restricted to specific fields such as date and time of recordings, specific recording station, solar conditions such as zenith and illumination, and weather conditions like precipitation and barometric pressure.