Editor’s note
The following abstract describes a publication that is only available as a downloadable PDF.

CoverDeveloped by Montana State University Extension and the University of Wyoming
Adapted with permission

This guide is one in the Exploring Energy Efficiency and Alternatives (E3A): Solar Electricity for the Home, Farm or Ranch series. This one provides guidance for determining the correct size for your system.


  • Solar electric photovoltaic (PV) system worksheet
  • Solar radiation U.S. map
  • Solar radiation data for flat-plate collectors and panels


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