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NREL's PVWatts® Calculator

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations.
Welcome to the updated PVWatts® Calculator!

PVWatts® now uses solar resource data from the latest NREL National Solar Radiation Database.
The data covers the Americas including Hawaii between about 21° South latitude (about 300 km North of Sao Paolo, Brazil) to about 60° North (about 200 km south of Anchorage, Alaska), and the Indian subcontinent and parts of Central Asia. We recommend that you use the new data, but you can still use legacy data if needed.

We also changed some labels, updated a few default values, and revised the Help documentation. See What's New above for details.