A SAM weather file is a text file that contains one year's worth of data in hourly or subhourly time steps. The data describes the solar resource or wind resource at a particular location. A weather file may contain typical-year data that represents long-term historical data or single-year data for a particular year. The solar resource and meteorological data in a SAM weather file may have been developed from ground measurements, data from a satellite, or a combination of the two.

For more information about weather data for SAM, see the "Weather Data" chapter in SAM's Help system. The Help system is available in SAM from the software's Help menu, and as a PDF file on the Download page.

For a description of SAM's weather file formats, see the "Weather File Formats" chapter in SAM's Help system, or download the PDF excerpt from the Weather Data Publications page.

Where to find Solar Resource Data to Use with SAM

The NREL National Solar Radiation Database (NSRDB) provides free time series weather data for many countries of the world. You can use the Download buttons on SAM's Location and Resource input page to download NSRDB data directly from SAM.

Note about snow depth data. If you are looking for snow depth data to use with SAM's detailed photovoltaic model, please see this post on the SAM forum.

Other Sources of Solar Resource Data

If you know of other data sources to add to this list, please contact us.

The following sources in addition to the NSRDB provide free weather data:

SourceRegionDescription
AUSTELA Australia Single-year hourly data (select years between 1996 and 2011). SAM-ready TMY3 format. Free.
EnergyPlus Global Typical-year hourly data from various sources. SAM-ready EPW format. Free.
Climate.OneBuilding Global Typical-year hourly data from various sources. SAM-ready EPW format. Free.
European Commission PVGIS Global Typical-year hourly data from various sources. SAM-ready EPW format. Free.
SIREN Toolkit Global Single-year (1979 - present) from NASA MERRA-2. Use makeweather2 program in toolkit or download separate sen_makeweather_getmerra2 package. Free.
NSRDB Archives United States Original typical-year hourly data files with additional data and documentation for legacy NREL NSRDB 1961 - 1990 (TMY2), 1991 - 2010 update (TMY3), and 1998 - 2014 update (TMY3). TMY2 files are also available in SAM CSV format (ZIP 23.3 MB). Free.

The following sources are are for commercial data products that will work with SAM:

SourceRegionDescription
SolarAnywhere North America, South America, Africa, West Asia, Europe Single-year and typical year data. Satellite-derived data. Free and $$.
Deutscher Wetterdienst WebWerdis Germany and other countries Single-year data. Free and $$.
Meteonorm Global Single-year and typical-year data. Model-generated data from various sources. Various formats. $$.
SolarGIS Global Single-year and typical-year data. Satellite-derived data. $$.
Solcast Global Single-year and typical-year data. Satellite-derived data. Free and $$.
Vaisala Global Single-year data and typical-year data. $$.
White Box Technologies Global Single-year and typical-year data. $$.