What Makes a Good Solar Site

Wednesday, June 17th, 2009

To assess the feasibility of installing a solar system, several factors have to be considered:

  • Orientation
  • Structure
  • Distance to transmission lines


The orientation of solar panels to the sun affects the efficiency of the system. East facing panels are 81% efficient. South facing panels are 87% efficient. A complete residential solar system is 83% to 85% efficient. In Rhode Island, solar panels are exposed to the sun’s photons for about 4.23 hours each day in average, therefore proper orientation is crucial to maximize a solar system.


Not all structures can support solar systems. If the solar panels are to be installed on a roof, the structure must be able to support panel and rack weights, and ballast if applicable. The structural effect to the building due to the increase sail from the solar panels must be analyzed to prevent any building structure failure. Finally, wind loads pushing behind the panels and snow loads in winter are other elements to consider and study.

Distance to transmission lines

In the case of commercial solar “farms”, generated electricity must be fed into the electrical grid. Proximity and access to transmission lines are key; building new transmission lines can be very costly.

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