Question on mounting solar panels

[funfyzics]

Recently I had a flexible solar panel fly off my roof and I am looking to replace with glass panel. How do you safely fasten mounting brackets to a thin travel trailer roof which may only be 1/4 or 3/8 inches thick OSB or plywood if you are lucky. I don’t want to lose another panel!!!!
Also, is there a possibility of hitting electrical wires when screwing into a roof?

Thank you

Brian

[A32Deuce]

I drilled starter holes (about a quarter the size of the screw I used), used screws that fit the hole in the bracket, (3/4 inch). To mount, I put Dicor at each hole location, screwed the,panel down(don't over tighten), then put Dicor over each bracket and screw heads on the roof. Then let it sit for several days before driving. Did this back in 2012 and still tight on the roof. I check them each time I'm up there.

[boondocking]

I did the same plus Dicor not only at the hole locations, but under the whole bracket and # 10 sheet metal screws.

[woo10-210]

Same as above with the Dicor under and over but I use #14×3/4" stainless truss head sheet metal screws. The coarse threads bite well into the wood roof material.

[Escapenrv]

Since 2005, on 4 motorhomes, I have used 3M VHB Tape. Very High Bond. It works very well. Only had to add 1 screw per bracket on a motor home that did not have the roof material glued down well.
This tape used to mount road signs and other out door items for years.
Great stuff.

[PSU Turf]

I used well nuts. First, I used a razor to cut a small hole in the TPO membrane so that the drill bit would not snag the membrane and cause a tear. Drilled the hole, put a dab of Dicor in it. Press in the well nut. As the bolt threads in it squeezes the well nut. The bulge in the well nut is below the thin plywood.There is no way to pull the nut out unless you back off the bolt. Covered the bolt head and mount with Dicor.
I thought about using the VHB tape but there are small areas on my roof where the membrane did not adhere very well to the plywood underneath.

[gordonsick]

I mounted two flexible solar panels on my roof with 3M VHB tape and Sikaflex sealant. No screws.

I bought a really big roll of the 3M VHB tape from a sign maker. I read the 3M documentation to make sure I was ordering the highest strength of VHB. At the hardware stores, they often have two versions of VHB tape and one is stronger. The same for the bulk purchase. I don't know why anybody would want the weak bond unless they expected to be removing the object.

When I contacted Go Power, they said that either 3M or Sikaflex would do the job. I decided to use both.

They have remained firmly in place since 2016.

[dfreeman]

Originally Posted by PSU Turf

I used well nuts. First, I used a razor to cut a small hole in the TPO membrane so that the drill bit would not snag the membrane and cause a tear. Drilled the hole, put a dab of Dicor in it. Press in the well nut. As the bolt threads in it squeezes the well nut. The bulge in the well nut is below the thin plywood.There is no way to pull the nut out unless you back off the bolt. Covered the bolt head and mount with Dicor.
I thought about using the VHB tape but there are small areas on my roof where the membrane did not adhere very well to the plywood underneath.

This is the preferred way to mount solar panels to an RV roof according to Renogy USA when using the Z clips. I have installed 4 panels using the well nuts and they are still holding tightly.