westend wrote:
Sorry to have come down a bit harsh on the plastic mounts, they may be just the ticket for some folks. I get somewhat wound up with my DIY metal working sometimes and can't see the reason to do it any other way.
I see where most guys figure out quickly that, if attaching a module using the factory made holes, it is darn near impossible to remove the module from the mounts because of the fastener locations.
I think I came down on plastic mounts harsher yet, and for a good reason. Plastic will work for "some" folks - for those who are not camped out in hot and sunny areas most of the year. UV radiation turns plastic into dust. Plastic plumbing vent on my trailer, left on the camp in North Baja, has crumbled to pieces in one year. This location is not that much hotter and sunnier than AZ. Fiberglass cover on AC developed small spiderweb cracks around corner bolts, and I can't think of any other reason than sun. Oddly, soft plastic vent on the fridge is like new. Some plastics are more UV-resistant than others, though I still don't see why not using aluminum mounts.
No matter what material you use, the mounts should allow taking the panel off without removing tapping screws from the roof. As noted, factory holes in the bottom of the panel frame are difficult to access once the panel is installed.
Some people use L-brackets with bolt or pin into the panel side, the L is basically a short 5"-6" piece of 3x3 or 4x4 aluminum angle. Others use Z-brackets made of pieces of aluminum angle, one piece is attached to the roof, another one to the bottom of the panel, and then both pieces are bolted together. This allows for height adjustment, so you don't need to be very precise.
Important detail - the panel should conform to the roof slope, rather than being horizontal relatively to the ground. That little slope will help shedding water and debris.
