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Old 03-26-2016, 08:58 PM   #1
Join Date: Apr 2015
Location: Long Island, NY
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Solar Panels On Paper Thin Roof

Started installing two 100 watt panels on the roof today.
I drilled a small pilot hole for the mounting screws, drill bit goes right thru, like hardly any material there, roof can't be more that a 1/4" thick (I'm being generous). I turn the screw in to test the hold, get to the end and the screw keeps turning, never able to tighten, dam what's this roof made of, 1/8" plywood? The previous owner had a laminate of sorts installed over original roof so i can't tell what the original is made of (i know thin plywood from my exploratory drill hole). I decided since I can't get screws to tighten the only sure way of holding the panels to roof would be toggle bolts.
With the smallest toggle bolts I had to drill a 3/8" hole for the toggle to fit thru, yikes I hate holes in the roof of any size. Then I Dicor the crap out of the bracket and screw.
I'm wondering if the Dicor alone would hold the panel to the roof (like glue)?
I'm not chancing it hence going with the toggle bolts as much as I didn't want to.
What have others used to secure panels to thin roof materiel?
I'm I missing something? I got one more panel to mount.
This job is turning out to be a major hassle at every turn.

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Old 03-26-2016, 09:20 PM   #2
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I didn't have a problem mounting my panels but I have a thick fiberglass roof. I still used Dicor between the mounting brackets and roof then topped the screws with dicor.
IMHO, I would go with the toggle bolts and Dicor. I can't imagine the toggle bolts pulling out but use the Dicor to prevent leaking.

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Old 03-26-2016, 09:59 PM   #3
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I used both toggles and mollys on the inside walls. Paper thin also. There's Styrofoam in the roof and walls but the toggle will expand. Maybe a washer would close the excess hole up?
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Old 03-27-2016, 09:39 AM   #4
Join Date: Apr 2015
Location: Long Island, NY
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What size toggle bolts did you guys use?
I used the smallest I kind find, 1/8, I wanted to keep the hole in roof to a minimum and I only used one per bracket (there are two mounting holes per bracket).
2010 Coachmen Prism M240
(2008 Freightliner 3500 chassis)
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Old 03-27-2016, 11:30 AM   #5
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I would tap to find a rafter/support. Todays roofs are way too thin, do you really think a solar panel will stay for long at 65 mph and a 30 mph head wind? I'd be checking the mounting often. Too bad manufactures who say Solar Ready" mark the mounting locations like they do for TVs.
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Old 03-27-2016, 12:27 PM   #6
Join Date: Apr 2015
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Finding and using a rafter support would be great but due to space limitations I only have a few inches either way to secure the panels to the roof. If i could find the roof supports I would have to fabricate a base plate to match panel brackets
Ya that's a real concern about wind and I will check often, thanx.
All my improvements always turns out to be a lot more complex than it seems to be on the surface. I can never leave things alone, when will I learn!
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Old 03-27-2016, 12:41 PM   #7
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Roof mount solar panel

Last year I mounted a flexible 100W panel to the roof of my 21DS between the front vent and AC UNIT. I first cleaned the roof, applied outdoor double stick closed foam tape and ducor to the roof. Put weights on it for a couple days and then filled yo with ducor caulk on the edges to make the seal. Cables were laid flush over the roof to the edge, run down inside awning bracket, inside storage and out front to solar controller and battery. Cables on roof were flooded with ducor. It all holds ok. 2nd thought though. Mount two rigid alum brackets between front vent mount and AC mount. Attach rigid 100W panel there.
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Old 03-27-2016, 12:51 PM   #8
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You have hit the nail on the head. I would use thin aluminum as a base strip for either side of the panel legs. This will allow you more area to secure the aluminum to the roof with toggle bolts. You can also use butyl tape under the metal and seal the edges. I would use upgraded self taping mounting screws for the panel brackets, then Dicor over the screws and bottom of bracket. This should have plenty of support while traveling and have a nice finished look.

I did a similar type of attachment base for a portable satellite dish holder, near the rear of a fifth wheel.
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Old 03-27-2016, 12:57 PM   #9
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Works for me

I had the same issues with mounting solar panels on the roof.
First I ordered extra brackets (6 per panel instead of four).
After setting the panel mounts on Dicor and tightening the screws just until they seated the mount to the roof.
After this I the drilled thru the roof into the interior in place of one screw in each corner bracket (Total of 4 places per panel.
Then using longer screws (about 2.5" long I used "T"-Nuts on the inside and tightened them until flush with the ceiling.
The screws just stick past the side of the "T"-Nuts and with a little white touch up paint you don't even notice them.
This may seem like over kill, but having a panel blow off would take the fun out of a camping trip.

I have four panels on the roof near the front so there is lots of wind and have pulled the trailer over 2400 miles without any problems at all.

You may consider staying with four mounts and drilling one of the holes in each mount thru the roof and using a "T"-Nut inside, I went a bit overboard.

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Old 03-27-2016, 01:02 PM   #10
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Location: Tulsa, OK
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solar portable

Too scary for me so I went portable panels with Trimetric SC2030 controller & TM2030 monitor permanently. Mounted with quick disconnect for panels works great and I still get to park in the shade. Takes less than 5 min to set up.


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roo, roof, solar, solar panel

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