The NSRDB is a serially complete collection of hourly and half-hourly values of the three most common measurements of solar radiation—global horizontal, direct normal, and diffuse horizontal irradiance—and meteorological data. The current NSRDB is modeled using multi-channel measurements from geostationary satellites. The older versions of the NSRDB were modeled using cloud and weather information primarily collected at airports. A sufficient number of locations and temporal and spatial scales were used to represent regional solar radiation climates accurately.