Solar Resource Data

Solar resource data is solar irradiance and meteorological data that describe the conditions at the system's location. PVWatts® uses a set of weather data prepared from the NLR National Solar Radiation Database (NSRDB) where it is available, and a collection of data from other sources for the rest of the world.

PVWatts® uses hourly typical meteorological year (TMY) data, which is one year's worth of data that represents the solar resource over a multi-year period. For more details about TMY data, see this NSRDB article on TMY data.

When you type a street address or latitude and longitude for the system's location, PVWatts®shows the latitude and longitude of the NSRDB grid cell for the location and the distance in miles between the location and the grid cell center. For locations outside of the NSRDB area, it shows the coordinates or name of the nearest available solar resource data site.

Image showing grid cell coordinates and distance between location and center of grid cell. If you are visually impaired and cannot read this graph, select the Need Help link at the bottom of the page for assistance.

PVWatts® also displays a map with a rectangle representing the NSRDB grid cell and a red pin indicating the system location. For locations outside of the NSRDB area, the map shows pins for the nearest available data sites.

Image of map showing NSRDB grid cell and system location with cursor to move grid cell. If you are visually impaired and cannot read this graph, select the Need Help link at the bottom of the page for assistance.

If you enter a location without a grid cell, PVWatts® will suggest the closest available data within 100km. If no data is available within 100km, PVWatts® will ask if you want to extend the search to 1,000km.

Note. It is not possible to run PVWatts® using your own solar resource data file or a data from a source other than those discussed here. If you want to run PVWatts® simulations with your own solar resource data file, you can use the version of PVWatts® in NLR's System Advisor Model.

The NSRDB solar resource data for PVWatts is a special set of files from the NSRDB. These files were collected from the following NSRDB datasets:

Solar resource data sources for locations not covered by the NSRDB include: