Wind and roof solar panels

[astrocamper]

I used the 3 inch high stainless steel Z brackets with 2 large screws per bracket. I used 8 brackets for each of my 300 watt panels. The 3 inch high brackets allow more air flow under the panels which helps keep them cooler under full sun.

[Yosemite77]

Originally Posted by corn18

…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:…

I have a TPO membrane roof, on which I used the same stud finder. I had mixed results using it, mainly because Coachmen had put a layer of foil on the backside of the roof sheathing. Despite having mixed results using the stud finder on the roof, I have no regrets on buying it. It’s by far the best stud finder I have ever used, and I consider it totally worth the expense.

On my roof I could tell where the joints were between the 4 ft plywood sheathing panels, so I knew where some of the roof trusses had to be located. While my 5er was parked in the driveway, I happened to look out a window overlooking the trailer one morning. This was early, before the morning dew had evaporated. With the dew on there, you could see exactly where all the trusses were located. Coachmen had laid them down 16” on center.
FWIW, I used a combination of screws and well nuts to anchor my panels down.

[computerguy]

If you are leaving them flat it is simply not going to be a problem IMO.
Completely different story if you intend on tilting them and leaving them tilted in extreme winds.
I installed mine on a membrane roof in 2016. 6+ years, 30,000+ miles and not a problem. You'll be very surprised at how little wind pressure actually will hit the panels mounted flat and within inches of the roof.
A fiberglass roof is considerably stronger than my membrane roof with the thinnest of thin luaun under it.

[JaguarAZ]

I've used VHB tape on my fiberglass roof with no problem. I made 2" x 3" brackets at each corner of the 200 W panels and used the double sided tape. After taping the panels down used dicor self leveling caulk over the edges.

When I upgraded panels after a few years the tape came off relatively easy. I used a putty knife to scrape off the dicor then used 91% isopropel alcohol. working it into the tape with a putty knife. The alcohol dissolves the adhesive and after a small amount of work pops the brackets right off.

[rockwind]

Originally Posted by Yosemite77

I have a TPO membrane roof, on which I used the same stud finder. I had mixed results using it, mainly because Coachmen had put a layer of foil on the backside of the roof sheathing. Despite having mixed results using the stud finder on the roof, I have no regrets on buying it. It’s by far the best stud finder I have ever used, and I consider it totally worth the expense.

On my roof I could tell where the joints were between the 4 ft plywood sheathing panels, so I knew where some of the roof trusses had to be located. While my 5er was parked in the driveway, I happened to look out a window overlooking the trailer one morning. This was early, before the morning dew had evaporated. With the dew on there, you could see exactly where all the trusses were located. Coachmen had laid them down 16” on center.
FWIW, I used a combination of screws and well nuts to anchor my panels down.

What are well nuts?

[rockwind]

Originally Posted by 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.

Those are big panels. How many did you fit on there? Were you able to do two rows of them on either side of the roof? I am having trouble finding panels that are about 36 inches wide

[Yosemite77]

Originally Posted by rockwind

What are well nuts?

A well nut is a fastener that expands below the surface as it’s tightened. Here are a couple pics that should be helpful.
[ATTACH]
[ATTACH]

[153stars]

If I remember right well nuts used to mount roof rack on some old station wagons and SUVs.
I think the solution is to catch a roof member with at least one screw per mount. Doesn't 07 Dynasty still have full steel cage. I have seen pics structure of my 95 there's a lot of members under roof. Couple decent rare earth magnets should be able to identify edges of beams. Pretty sure my roof has 1/2" plywood under a one piece fiberglass roof that is bonded to luan for enough rigidity to assemble. Plenty of meat for a second screw .

[SJ-Chris]

Guarantee!


I have a suggestion for you that is 100% guaranteed to be TWICE as good as using 4 Z-brackets and VHB tape. Are you ready for it?? Here it is......Use 8 Z-brackets with VHB tape per panel!


Seriously...the VHB tape is very strong. Go with 8 brackets per panel and they should never move.


Good luck!
Chris

[vsheetz]

VHB tape and/or screws. Proven methodologies.

Rather than Z bracjets or similar, suggest to use rails of unistrut with panels attached to the rails.

Tilt brackets can be used if desired spanning across the rails. Even if not tilting they allow fir easy cleaning and wiring access.

Additionally risers can be used to loft the panels to help mitigate self shading.

[cruizerEd]

Originally Posted by dallas121469

...
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.
...
Any thoughts would be greatly appreciated.

Here is a document I have created from answering this questions a few times and giving AM solar feedback on their installation practices.

[rarebear.nm]

On our Excel 5th wheeler when I mounted three 350 watt panels I used six custom Z brackets per panel. Each Z bracket is 6" long x 4" wide at the mounting base. I used four stainless steel screws for each bracket going into 3/8 plywood under a membrane roof. I used Dicor under each bracket, then screwed it down and flooded the bracket and it's backside with more Dicor. That was 5 years ago and no issues.



RV manufactures have used many different roofing systems over the years. I'm sure that there are some unusual systems out there.


Fiberglass roof laminated to foam provides little to no solid material to screw in to or even use expanding nuts. So adhesive/tape is the common choice.


A few roofs that have structural fiberglass roofs, like our Coach House Class C have plenty of material to screw into or at least use an expanding nut under it. Tape would also work good.


I have not been on many metal roof tops. Some are very thin metal over some rafters, wood or metal. Others are layered over a wood base. For the first case I think you really need to find a rafter to screw into. Possibly a rail system. I doubt how well tapes would work on thin metal, too much play in it. The second case would allow multiple mounting options.


I know many people are understandably nervous about putting any holes in there roofs. I just look around at an RV roof top and see so many places that screws have already been used. Like around vents, A/C units, skylights and vent pipe caps and cable entrances. Not to mention the very large holes for the vents and A/C units. So I figure I can take my time and make sure every hole is fully sealed as well or better than any factory screws. We all understand the quality problems from some of the RV manufactures. IMO- there are some notable exceptions.


I've replaced many roof vents and power fans and other stuff on RV roofs I really don't think twice about another screw. I just do it right the first time.