An energy audit and solar assessment will help you determine how much of your electricity needs can be met by a solar electric system.Energy efficiency lowers your electricity needs and can save you thousands of dollars on the up-front cost of solar. 

Solar Potential.  Solar electric systems perform best with unshaded, south-facing exposure.  Shading reduces system performance and can be caused by trees, nearby buildings, chimneys, and other roof obstructions. East- or west-facing exposures can be used for a system but with reduced performance. Systems can be mounted on a wide range of roofing materials as long as the roof is in good condition; they need to support the weight of the system for its useful life. A solar electric system may also be installed with a ground-mounting.

 

Energy Needs.  Your PG&E bill gives you information about your annual electricity usage. To estimate how you could meet those needs with solar, consider that on average 100 ft2 of installed silicon modules can provide approximately 1,425 AC kWh of electricity a year.