VHB tape for solar panel mounting... ever come loose?

Well, I asked because I chickened out and put one screw in each of the mounting brackets for each of my 100w panels. Each bracket foot was 1.5 x 1 inch, four brackets per panel. Honestly, I think it would have held with just the tape. I used the 4950 tape, .040 thick IIRC. That appears to be what AM Solar uses. My roof is pebble-grain fiberglass. I really didn't mind using the screws, it's not like there aren't already a hundred of them in my roof.

I have 5ea. 100W panels on the roof using 4950 tape holding AM Solar Stainless feet and they all are rock solid.

Several years ago I asked Deb @ AM Solar if they have ever seen any come loose, and she said only once on an install they did not do, and it just looked like improper application.

Fred: Read the data sheet on this stuff. You could pick up an entire roof with that much tape.. :)

VHB Data Sheet

If you pre clean the area as per the directions the tape will not be removable. If you have a fiberglass or metal roof you are in luck and have this as an option and it is safer than doing a roof penetration in terms of avoiding leaks and having better holding strength. This material has been used in aerospace and aviation applications and is a proven technology.

VHB has a surface that conforms to the pores of the surface so it should be used on a relatively smooth surface for maximum adhesion. There may be a type that works on pebbled surfaces and I would look for this specifically if the RV roof has that texture.

Personally I would want the tape to cover about 3" X 6" minimum, even if the bracket is not that large. This would give 18 square inches of tape on the roof surface. If the tape has a pull strength of say 1 pound per square inch, more on the roof will cover more area, and this will be a stronger joint than just say 2" X 4".

When my instructions for my original solar system came, it said that using rubber roof sealant below the 'bigfoot' brackets can allow you to not have any screws into the roof. I put in screws anyway. The brackets are about 3" X 4".

Fred.

I mounted a solar panel on top of my roof AC a few months ago. It has held firm so far. I'll have to take some pics. That 3M VHB tape is amazing.

I used VHB4950. It's been solid for 8 years. I didn't know how strong that stuff was so I went overboard on contact area. Each pad used two 2x2" angle Al, 6" long. I have 24 sw inch contact surface.



I tilt in the winter. It takes just a couple of minutes to tilt. Very simple.