Bolting solar panel brackets to roof - Fiberglass RV

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Old 03-18-2015, 10:01 PM   #1
Name: Andy
Trailer: Trillium
Posts: 79
Bolting solar panel brackets to roof

So we're close to starting the install of two 160w panels to the top of our Trillium 1300. We are going to drill into the roof (I know...) and mount these with Z brackets. A couple concerns... I'm not too worried about sealing from leaks, but as far as the bracket on the roof itself, should we have some sort of dense rubber between the roof and the bracket or would direct contact be ok? I just don't want the roof to crack from any possible flex. Also, we have to clear the center riser of the roof which is 4" tall at center. So the panel is doing to be very close to the center riser but will have a 4" gap under it on the outer ends. Should we be concerned with air flow under this while traveling? These panels are 26x57" each by the way.

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Old 03-18-2015, 10:14 PM   #2
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Name: Fred
Trailer: 13 ft Boler
Kootenay's of BC
Posts: 812
I think you should consider some sort of "foot" between the bracket and the roof and on the inside ceiling to spread the load out.
If the panels are fairly level or square front to rear on the trailer wind shouldn't be an issue , is there a midway mount down the long section?

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Old 03-18-2015, 10:29 PM   #3
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Name: Lauren
Trailer: '75 Trillium
Posts: 18
Hi Fred - The camper is AJDemo's and mine. I've got the keyboard at the moment, so I thought I'd jump in.
We'll be mounting the 2 panels parallel to each other, but perpendicular to the direction of travel. Mounting spots are only on the long sides; two on each long edge.

Do you have any recommendations for the "foot?" I considered whether we could put something on the inside to spread out the stress of the screws, but how big would we need to go? A larger washer? bigger?

Any pros or cons to bolting the 2 panels together and mounting as one, and keeping the middle mounting positions?

Thanks for any insight.

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Old 03-18-2015, 10:51 PM   #4
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Name: Fred
Trailer: 13 ft Boler
Kootenay's of BC
Posts: 812
I don't have any experience with solar panels so it's hard to give recommendations as to their mounting but together they would make quite a wing and could catch a lot of air. Some one else will have to chime in as to their integrity against the wind.
As far as a foot, it would need to be firm like plywood, and water proof like plastic, with some uv resistance. I would tend to have it inside and outside the trailer acting in a clamping manner to the trailer.
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Old 03-18-2015, 11:37 PM   #5
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Name: Dave
Trailer: Casita SD17 2006 "Missing Link"
Posts: 3,739
Andy, I know a bunch of folks don't like putting holes through the shell but it's not going to be a real problem for something as light as this. There have been many posts on solar panel mounting. I don't have any problem with drilling holes if need be but if I was going with rooftop panels I think I would use VHB tape only because I wouldn't have to deal with the bolts on the interior for looks. I would bolt the panels to the mounts though, so they could be removed if needed. There are a few members that have used VHB for panels for years and many miles with no problems. I don't see an issue with cracking from stress if bolted although you could use a wider "foot" to spread the load a bit and butyl tape with no rubber insulation material. One member if I remember right, did put an angled leading edge on to put a little downward wind pressure on the panel when towing.
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Old 03-19-2015, 09:10 AM   #6
Name: milton
Trailer: Northern Lite
British Columbia
Posts: 33
Solar Panel mounts

I have a 150 watt panel on the roof.The feet are wide curved pads (4X6) screwed into the curved outer edge,held down by stainless screws and caulked.It's basically a roof rack,with a framed panel attached.I recommend an articulating mount to better track the sun.It'l boost the amperage .Milt
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Old 03-19-2015, 11:47 AM   #7
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Name: Carol
Trailer: Scamp / 1949 Hudson
Posts: 27
We mount a lot of stuff on a boat...and they always recommend a "backing plate" on the inside to spread the pull against it. Thinking of adding a solar panel to our scamp and if thru bolted we'll have a 4" backing plate.
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Old 03-19-2015, 01:23 PM   #8
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Name: Larry
Trailer: Casita 17 LD
Posts: 208
Mounting your solar panels

I have done two different solar panel mounts and both times I used aluminum strips bolted or riveted to the panel and then rivet the aluminum to the fiberglass with 3M VHB tape between the aluminum and fiberglass. I have not had any leaks and I had a heck of a time removing the first installation in order to do the second. You can see by the picture I am testing the limits of aero-dynamics with my current installation of 5 panels totaling 400 watts. This last winter we took a 9 week trip of 6000 miles and had no issues with the solar panels and I know I exceeded 80 MPH more than once and many encounters with tractor trailers going the other direction on a 2 lane road at 65 MPH. Post trip inspection revealed no damage or loose bolts or rivets.
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Old 03-19-2015, 01:39 PM   #9
Name: rick
Trailer: scamp 16 [front bath]
Posts: 36
Mounting solar panels

I share your concerns and my solution was to purchase some large round rubber washers from my local hardware store to "cushion" the installation between the Z brackets and the fiberglass. I also spread a small amount of a quality caulk in the drill holes before inserting the rivets to provide some added insurance that a leak would not be in my future. So-far-so-good! Don't have quite the wattage that you will have.
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Old 03-19-2015, 05:11 PM   #10
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Name: Tim
Trailer: '88 Scamp 16, layout 4
North Florida
Posts: 1,487
I have purchased, and have room for three 100 watt panels on top of the Scamp. My plan is to mount them with through bolts on the front (leading) edge brackets and 3M tape under the others. I figure if the front does not go (fly off) the rest will not either. I also plan to make a short aluminum airfoil and mount it in front of the panels to deflect air and flying crap up over the panels.
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Old 03-19-2015, 06:40 PM   #11
Name: Andy
Trailer: Trillium
Posts: 79
Thanks for the input so far everyone. Larry, nice Casita! Looks like we need to make a trip to the hardware store to look for materials for the "feet" of the panels. I'll have to see how the panels look once they're on to figure out if we need something in front to push airflow over the panels. We're pretty excited for this project and it starts next weekend. I'll be sure to post up a thread of photos, documenting the process.
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Old 03-20-2015, 07:55 AM   #12
Senior Member
Name: Steve
Trailer: Scamp 19
Posts: 174
I installed two 50w panels on my roof top on my Scamp 5er. I used 3M VHB tape that I got at Amazon. I did use a couple of pop rivets, two one of each of two feet that didn't sit flat on the roof top. I also used 3M 5200 sealer on the holds with he rivets as well as putting a bead around each foot. I now have over 10,000 miles of driving with the panels mounted and haven't seen any sign of movement. I used aluminum rivets, not through bolts as I figure if anything get damaged I would rather have the panels damaged and not damage the fiberglass shell.

My panels don't have hinges and lay flat all the time. I find that my batteries are fully charged before noon. With solar I have changed all my interior lights to LED's
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Old 03-20-2015, 07:18 PM   #13
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Name: Cathy
Trailer: Scamp
Posts: 16
What about a 4 x 4 square of vinyl fence? Waterproof, especially if you put a washer between the foot and the vinyl.

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Old 03-20-2015, 10:26 PM   #14
Name: Andy
Trailer: Trillium
Posts: 79
Today I found 12" square rubber sheets about 1/8" thick from the hardware store. We may have to double up but I think this should work.

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