The National Solar Resource Data Base (NSRDB) compiled by NREL contains measured and modeled solar irradiance and weather data for two time periods:
- 1961-1990 – Original version (237 National Weather Service sites in the U.S. including sites in Guam and Puerto Rico). This data is the basis for TMY2 files.
- 1991-2005 – Update version (1,454 locations in the U.S. including territories). This data is the basis for TMY3 files. This has been superseded by the update below.
- 1991-2010 – Update version (1,454 locations in the U.S. including territories). This update made in 2012 includes 10-km gridded data from SolarAnywhere, a satellite irradiance product from Clean Power Research.
