Properties with good solar potential have the following things in common:
- They have plenty of roof or ground space that can be used for array(s)
- 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