Properties with good solar potential have the following things in common:

  1. They have plenty of roof or ground space that can be used for array(s)
  2. There is very little shade (few trees or neighboring buildings)

Ideally, the space available for arrays is South facing, however that is not a requirement. Roof surfaces with orientations of 45 degrees off south still receive more than 92% of what an optimally oriented roof would receive and roof surfaces with East-West orientations receive more than 74% of what an optimally oriented roof would receive. Tree shade is often more detrimental to a candidate site’s efficiency than orientation.

Have a look at the following to get a better feel for how orientation affects efficiency:

Solar Solutions for New Jersey, New York, and Eastern Pennsylvania