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PVWatts® Legacy Tools

These PVWatts® calculators are available as legacy tools only and will no longer be supported after 2014. Please update your bookmarks and visit NREL's PVWatts® Calculator.

On this page you will find the original Site Specific Data Calculator (Version 1) that allowed users to select a location from a map or text list of pre-determined locations throughout the world and the Grid Data Calculator (Version 2) allowing users to select any location in the United States via an interactive map. Version 2 provides access to multiple data sets that link directly to their corresponding PVWatts® Calculators, allowing the user to determine energy production and cost savings of grid-connected solar photovoltaic (PV) systems.

Both calculators are accessible through Version 2 by querying their corresponding data layers that feature weather data in the form of specific locations (239 TMY2 sites in the United States and 76 international) as well as a 40km x 40km grid which covers the United States.

To use the PVWatts® legacy calculators, see: