Wind and roof solar panels

[dallas121469]

Wanting to take the solar LiFePo leap but concerned about the long term stability of attaching solar panels to my fiberglass roof.

In the videos that I've watched nobody seems overly concerned about finding something solid into which screws can be attached. They just place the panels in a "good" spot and drill away willy nilly.

I routinely drive through Wyoming and have experienced wind gusts up to 70 mph. Even had an awning cover get ripped off and damage my roof.

I don't see how 4 screws drilled into fiberglass will keep my panels from ending up in a field in Wyoming next time I drive through in the fall. I realize they are laying horizontal but still seems sketchy to me.

Any thoughts would be greatly appreciated.

[amosnandy]

Originally Posted by dallas121469

Wanting to take the solar LiFePo leap but concerned about the long term stability of attaching solar panels to my fiberglass roof.

In the videos that I've watched nobody seems overly concerned about finding something solid into which screws can be attached. They just place the panels in a "good" spot and drill away willy nilly.

I routinely drive through Wyoming and have experienced wind gusts up to 70 mph. Even had an awning cover get ripped off and damage my roof.

I don't see how 4 screws drilled into fiberglass will keep my panels from ending up in a field in Wyoming next time I drive through in the fall. I realize they are laying horizontal but still seems sketchy to me.

Any thoughts would be greatly appreciated.

There is no reason to drill ANY holes in your fiberglass roof to attach your solar panels. The only way to put them on is with 3M VHB tape. Think about it. 4 small screws totaling maybe 1/4 square inch of adhesion, vs a 4" x 6" adhesive that has been proven to have more strength per square inc than screws and bolts, spread out over a much larger area, distributing stress on your fiberglass roof surface.

[jrollf]

Originally Posted by amosnandy

There is no reason to drill ANY holes in your fiberglass roof to attach your solar panels. The only way to put them on is with 3M VHB tape. Think about it. 4 small screws totaling maybe 1/4 square inch of adhesion, vs a 4" x 6" adhesive that has been proven to have more strength per square inc than screws and bolts, spread out over a much larger area, distributing stress on your fiberglass roof surface.

Keep in mind good prep is a MUST. The roof and mount plate where the VHB is going to be attached needs to be thoughly clean, no dirt or oils (including skin oil) to obtain a strong bond. Any contamination of the bonding surfaces can lead to failure of the VHB tape.

[sshephard1]

FWIW I have had 3 panels attached by 4 small screws each for 3 years to the top of my TT with absolutely no problems. I was worried at first but got over that. I have driven 65 mph against a 30 mph headwind, and I have experienced 70 mph storm winds more than once. The panels are still firmly attached. Given what others have said about vhb tape, I might have tried that three years ago if I had known about it. I do wonder, however, about how hard it would be to remove a panel if taped down or, if in the unlikely event of a panel lifting off in high winds, would the tape release or would the membrane under it tear off?

[vsheetz]

Originally Posted by sshephard1

FWIW I have had 3 panels attached by 4 small screws each for 3 years to the top of my TT with absolutely no problems. I was worried at first but got over that. I have driven 65 mph against a 30 mph headwind, and I have experienced 70 mph storm winds more than once. The panels are still firmly attached. Given what others have said about vhb tape, I might have tried that three years ago if I had known about it. I do wonder, however, about how hard it would be to remove a panel if taped down or, if in the unlikely event of a panel lifting off in high winds, would the tape release or would the membrane under it tear off?

VHB tape only used with fiberglass or other solid roof. Not to be used with any kind d of membrane roof.

Especially if installing with VHB tape I'd use a rail mounting system to accommodate any future panel upgrades or changes.

[dallas121469]

I like the idea of vhb tape over screws and I had already intended to use a rail type system over the fixed brackets.

Has anyone tried eternabond double sided tape?

[sshephard1]

Originally Posted by vsheetz

VHB tape only used with fiberglass or other solid roof. Not to be used with any kind d of membrane roof.

Especially if installing with VHB tape I'd use a rail mounting system to accommodate any future panel upgrades or changes.

Good to know. Thanks.

[Bsqrd]

Check this out. He put his on a fiberglass roof with vhb tape.
https://youtu.be/uvMYv7afUWM

[spierce617]

Originally Posted by Bsqrd

Check this out. He put his on a fiberglass roof with vhb tape.
https://youtu.be/uvMYv7afUWM

Exact video that I was thinking of as soon as I started to read this thread. Seems like this guy thought of everything and made a good decision to install like he did. I really like the rails that he used to attach to the roof.

[astrnmrtom]

I used screws, 8 per panel, but I used full width brackets and laid a good bead of Dicor caulk down before screwing the brackets in place, then Dicored over the screws. Still solid years later and completely leak free.

The way the wind blows over the top of the roof and the panels there's a whole lot less force than you might think. I remember one time I left something on the roof and drove for a couple hours to the campground. Got up on the roof and it was still there. I don't remember what it was, but I was shocked it didn't blow off because it was pretty light.

My fiberglass roof is the pebbly textured type, so I wasn't confident tape would work. I expect my panel installation, with proper maintenance, to last the lifetime of the panels. If that's 25 years, that could be longer than I'll be around.

[Bobby F]

I have a membrane roof over thin luan-type plywood, so I worried about this too. No such thing as a strong connection to such material. You look for lots of weak ones.

But I have not had an issue. I used the normal 4 z-brackets per panel, which gives me 8 screws holding down each panel. (Important to use the correct large-coarse-thread fasteners with a tight pilot hole, not the self-drilling ones. Self-drillers drill too large of a hole.)

I drive close to 70, and I've hit strong oncoming winds, with not a single panel movement. They're going edge-on into the wind, so there's not a lot of sail area for the wind to grab.

But I still hooked up a safety cable to all panels, in case one or more pull out, so I don't kill anyone.

[Nwcid]

Originally Posted by dallas121469

I routinely drive through Wyoming and have experienced wind gusts up to 70 mph.

Driving will you will experience constant winds of up to 70 mph..........

[corn18]

I have a membrane over luan roof. I have installed 6 panels using aluminum strut channel. I used 10 ft strut channel with two panels per pair of strut channel. I used 8 total attach points per pair of panels, so 4 attach points per panel.

For the first 4, I used the wet roof method to find cross members. Worked pretty good, but I missed in a couple of spots. And when I missed, there was nothing holding the strut channel to the roof. Made a few extra holes this way.

I tried using my stud finder I have owned for 25 years, but it just beeped randomly all the time. Then I read a thread on here about one that worked for RV roofs. I bought it and used it to mount the last two panels and it worked like a champ. Found cross members easily and when I drove the stainless lag bolts into where it said there was a cross member, it grabbed solidly. Very pleased.

Here is the stud finder I bought:

https://www.amazon.com/dp/B07564RSHR...roduct_details



Here's a pic of my install:

[rarebear.nm]

Plenty of good advice above.


RV roof construction varies greatly. Some are thin metal, some have 3/8 - 1/2 plywood under a membrane or fiberglass, some are fiberglass bonded directly to foam, etc. Some roof structures have a standard roof truss system, like every 16 inches, some have a few structural cross members where roof items are attached, some are solid foam with no structural members. Thus the best way to attach solar panels varies with both roof structure and surface type.


Our 5th wheeler has wooden roof trusses and 3/8 plywood with EPDM membrane. Thus VBH tape was a non-starter. My panels are like 49 x 79", rather large and they had to go over some roof vents. In the end I fabricated my own aluminum brackets, 1/4 thick x 6 long and 5" high. I used six brackets per panel and 4 screws per bracket. Dicor under and over every bracket. Seven years and many miles and all is still good.



I think if your roof layout allows it a good rail system is best.