The following scorecard to evaluate your roof as a potential site for a photovoltaic (PV) array has been developed by Solar Electric Systems.

ORIENTATION
The BEST solar orientation is true south (14 degrees east of magnetic south for Los Angeles). Southwest to west orientation is GOOD because electrical loads usually peak after noon. Southeast up to 20 degrees from true south is OK. South 10 Southwest 8 West 6 Southeast 4 Other 0

SHADING NO SHADING
from buildings, trees or other obstructions between 9AM to 4PM. Even partial shading from trees, bushes or power poles affects PV production. Roof dormers, vent pipes, antennas and other equipment near the south, east or west sides will shade the array during part of the day and should be avoided. No Shading 10 Other 0

ROOF PITCH OR TILT
The BEST array tilt for year round production is the latitude angle (34 degrees for Los Angeles). The latitude angle plus or minus 15 degrees is GOOD. 35 degrees 10 >From 20 to 35 degrees 8 >From 35 to 50 degrees 8 Other 0 to 4

ROOF TYPE
The BEST roof has COMPOSITION SHINGLES (asphalt or fiberglas) less than 10 years old. Wood and tile shingles require special treatment. The BEST roof underlay is sound 1/2 inch thick plywood minimum. The BEST roof framing is sound 2 X 6 rafters on 2 foot centers minimum. Best roof 10 Other 0 to 4

AVAILABLE SPACE
A 2 kW solar array of single or poly crystal solar cell modules requires approximately 300 square feet (12 X 25) of contiguous roof space. Amorphous solar modules require twice as much space. Sufficient roof space 10 Other 0

ROOF OBSTRUCTIONS
There should be no skylights, dormers, vents, chimneys or other roof obstructions in or near the solar array area. No obstructions 10 Obstructions 0

It's great if your site scores a perfect 60. But don't count yourself out if it doesn't. Call Eco-Home™ Network (323)662-5207 for a referral for a professional evaluation.