Graham, thanks for starting a roof mounting dialogue. In the spirit of the season and in the tradition of the PV industry sharing information, wrenches who send a 9 X 11 envelope and 74 cents postage, will get the structural engineering calcs and drawings for the roof mount that we used on 102 SMUD PV Pioneer 4 kW residential systems and 288 kW on Sacramento churches. The challenge was to design and install the lowest cost grid tied PV in the world on multiple sites. We limited ourselves to composition shingle roofs less than 10 years old with 1/2 inch or thicker plywood. Solar panels (7 each Solec SQ80 modules) were fastened with #10 wood screws into the plywood - not the rafters. Over 71,000 square feet of PV and no roof leaks despite the worse rainy season in 100 years in 1994-95 and winds over 80 mph at some sites. Of course, 20 years prior experience building roofs helped :-) but Placer Electric journeymen and apprentice electricians, not roofers, installed the roof arrays at union scale. If we can put a man on the moon in 10 years, we can surely install a few million megawatts of PV by 2010.
Happy holidays and best wishes for a prosperous new year.
Joel Davidson
SOLutions in Solar Electricity
P. O. Box 5089
Culver City, CA 90231

graham@solarexpert.com wrote:

Personally I believe roof mounting and attachment of solar panels is a very important subject
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