The policy of the DIY Solar Power group is for the homeowner (or his contractor) to install the mounting rails on the roof, for these reasons: 1) the homeowner can take his time do a proper job of attaching the mounting brackets directly into the rafters, and 2) the Group does not want to be responsible for any roof leakage due to improper sealing of holes drilled in the roof.
For homeowner installed systems, it’s very important to use a proper sealant when attaching mounting hardware to your roof. From an internet search, this is what we found.
First of all, don’t use a silicone sealant. It contains acids that cause corrosion to a metal roof and doesn’t adhere well to metal. The Propanel installation manual recommends a urethane-based sealant.
For shingle (composite) roofs, mounting brackets are available that have a flashing to slip under the shingles. It is also advisable to add a sealant under the flashing where you have drilled through the roof.
The following sealants are recommended for installing rooftop solar:
Henry 209 caulking (for composite roofing)
Solar Seal 900
Kikaflex (don’t use with asphalt shingles)
Titebond Metal Roof Sealant – available in colors
We don’t have any information at this time on which sealants work best and which are locally available. You can do further research on your own, or assume all work well since they are recommended by solar installers.