Re: Screwing into the roof

Don Phillipe

Make sure the surface is clean and don't do anything crazy like wiping it with your finger to feel what a good job you did prior to putting the feet in place.  The bond will only be as good as you are able to make it clean and a fingerprint is not something you want.   I laid out my panels after the feet were attached to the panel.  I placed each panel where I originally planned and adjusting them as needed after spotting any shadows from TV antennas, AC housings, etc.   I then marked around each of the feet on the roof with a series of red sharpie dots, then I lifted the panel out of the way and with it upside down I cleaned each foot on the panel with 600 grit sandpaper, wiped each foot clean with a lint free cloth and cleaned with denatured alcohol.   Then I cut and applied the sticky side of each piece of VHB tape to cover each foot pad while leaving the protective plastic from one side of the tape (on the foot's bottom) in place. 

I then returned to the roof area, setting the panel upside down and to the side, while briefly wiping the plastic feet bottoms with a moist alcholol lint free cloth..   Then I sanded each of the areas of the roof where the feet were to be placed, sanding with 600 grit sandpaper and cleaning off using progressively first paper towels to wipe away any degris and finally with cleaning each area with a bath of denatured alcohol and a lint free cloth.   I then with a helper lifted the panel up, flipped it feet side down and carefully set the feet to where they matched exactly the areas I had cleaned on the roof.  Now with the clean plastic tape cover on the bottom of each foot pad and with the four feet touching the clean area of the roof I had just cleaned and sanded, this left a perfectly clean to clean surface.   Then I walked around the panel while lifting each foot separately and peeling off the protective plastic sheet under the tape with a very thin and clean set of long nosed pliers, while making sure not to touch either the tape or the roof where the foot was resting.   I then just let each foot rest in place with the raw exposed tape now touching the roof until I managed my way around, lifting each leg slightly to remove the plastic covering.   Then this left the raw VHB tape touching the roof under each foot and I moved around the panel again, pressing each area above each foot into the roof and then slightly lifting to ensure it has stuck in place.   Then I applied the lap sealant generously all around each foot and let it dry 3 days (was still soft after 3 days of summer heat - may take up to a month to cure, so don't install with rain in the immediate forecast).    Then I ran the wiring (make sure your panel mounting feet are tall enough to get a hand under to reach for the wires, else you may have to remove the panel from the brackets just to unwrap the wire that needs to be run.  I actually had untangled the wires and taped the ends next to the edge of the panel so I could reach them easily after the panel was mounted.

Also to agree with what some have said, I've had VHB tape come undone when used to hold a kitchen appliance to my sink by prolonged exposure to simple dish washing liquid, so I'd make sure to cover the feet generously in the self leveling lap sealant to keep anything liquid out of there.

Also I'll second another suggestion here and that is to be aware of the curved roof and watch for un-level mounting feet which sometimes show up when you are mounting a panel facing long ways and spanning from left to right across the roof-top.   I ended up turning the feet where the long part of the foot went in the direction of front to back so that the curve of the roof did not affect it being uneven as much, then i bent it just a hair to follow the tilt of the roof which would have been impossible had I not made an alteration to flip the feet 90 degrees on the side to side width panel.

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