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Marco,

Personally I believe roof mounting and attachment of solar panels is a very important subject especially here in Los Angeles where we get fierce Santa Anna winds, which are immediately followed by the rainy season. Typically the only logical placement for solar panels in the city is on the home’s roof. This also creates a large potential risk for contractor liability. A number of years ago I was asked by a roofing contractor: why would someone who decides to get into the trades pick one in which dozens of holes are drilled into the membrane of roofs? I do not recall what my reply was, but I will now try and give some advice on this subject.

I also use the mounting products manufactured by Professional Solar Products. They have a great product line and the two roof attachment mounts that I typically use are the Tiletrac and FastJack. Whenever possible I try to pick installations where the homeowner is going to re-roof at the same time the solar is installed, even if this means postponing the solar job. The roofers tear-off the existing roof and this is when the FastJacks are bolted to the roof. It is very easy to find the rafters when the roof is removed. This is where the plywood is nailed to the rafters. We run chalk lines across the roof and bolt down a FastJack every 48 inches apart and use as many as the job requires. We typically leave about 24 American Metals 3/4" roof flashings for the roofers. They show up, felt in the roof, place the flashings over the FastJacks and then proceed to complete the roof installation. Upon completion of the roof we secure gold-galv Power Strut across the tops of the FastJacks. Then we bring up our pre-wired and preassembled solar panels which each consists of 4 Siemens SP75's. The SP75's were preassembled on aluminum rails which lay directly on the strut. The panels are secured by tightening down 1/4 thick aluminum angle brackets to the strut with strut grab nuts and self tapping screws into the side of the aluminum rails. Let the wind howl and the rains come. (Most roofers prefer metal flashings as opposed to Oatey flashings with the rubber boot. Oatey makes a Solar Flashing with an EPDM rubber boot which works well on a slopped composition roof, it allows for a lower profile and 3" FastJacks can be used instead of 4.5". When it comes to a flat roof that will be hot mopped only use metal flashings)

When it comes to installing panels on an existing roof which requires roof penetrations we use the TileTrac mounts. These mounts are about 8" inches long and have a sliding carriage which comes in handy for connecting rails and strut. Finding the rafters through a roof is always the most critical part. I have many different types of stud finders most of which seem to be less than 100% reliable. Sometimes it is easiest to feel under the eaves where the rafters are and then carefully bang the roof with a hammer where you think the rafter should be. The sound and feel if the hammer strike is different directly above the rafter, more solid and the vibration can be felt through your feet if you stand directly below the impact. Next a 1/4" pilot hole is drilled through the roof, if the rafter is not directly below the drill the bit will lose tension and pop into the attic. If the rafter is missed then we drill a new hole 1" to the left and if that one misses than another hole is drilled one inch to the right of the original hole. Hope fully the rafter is found and this is where the TileTrack mount is nice. It is long enough to cover any missed holes. We fill all holes with Sika flex sealant, cover the underside of the TileTrac with the sealant as well as the threads on the lag bolt. If the rafter was properly located and pre-drilled the bolt will tighten down very firmly and the rafter will not split. We almost always put our roof mounts 48" apart and since most homes have rafters either 24" or 16" on center this works perfectly. But I have learned that some framers had something else on their mind when the house was built.

Flat roofs are the trickiest and need the most attention. Most flat roofs in Los Angeles have a hot mop with gravel on top. Finding rafters is extremely important as well as roof preparation. The area where the TileTrac is secured must have the gravel removed, brushed with a wire brush and heated with a torch. We also heat up the sealant, typically Henry’s 204. If the roof is clean, hot and bubbling and the sealant is hot the mount will have a good thermal bond when tightened down.

Well I guess I have rambled on enough. I like the Pro solar mounts. They are also used by Siemens, BP, Astropower and Kyocera in their packaged systems. I have been using the FastJacks for most of my jobs. These are a great patent pending product with full engineering and I will continue to use the original product as opposed to the recently introduced knock off’s. I have seen copies of the FastJacks made locally here in LA and the bases hang up on the flashing, this will not make the roofers happy. I would also advise using mounts that have full documented engineering. If certain mounts do fail, the building department will cross check permits and find the jobs that have the defective or unsatisfactory mounts.

I show how to use FastJacks on this web page www.solarexpert.com/instroof5.html

Graham Owen

GO Solar Company