3M 5200 Adhesive caulk for solar mount with screws

[DAS26miles]

Mounting 100 watt solar panel using z brackets. Going to use 6 or 8 to be safe. Wondering do I put down adhesive caulk under each mount , lower and screw it down. Then cover with the adhesive caulk?

[SailingOn]

x2 VHB tape, no screws. At 42000 miles now, including two months in Alaska, all mounts still solid.

[CA_Traveler]

phillyg wrote:
If you use 5200 you'll for sure never get it apart. There is a solvent for it but it might damage the RV parts or roof.

That's why I used VHB tape.

[phillyg]

If you use 5200 you'll for sure never get it apart. There is a solvent for it but it might damage the RV parts or roof.

[docsouce]

As folks have said: use 3M 5200 if you plan on never removing the screws or the mounting brackets. The mechanics at the marina told me to use 3M 4200 on removable mounts and to seal mounting screws. Check out the 3M web page and check out the applications, You will see the 5200 is for a permanent application and the 4200 is for removable application.

[j-d]

CA Traveler wrote:
You will regret using Z brackets when you want to access under the panel for any reason. Cut 2 pieces of angle aluminum from HD and bolt them together in a Z pattern. Easy to remove that bolt.

To add to the above from my boating experience: "You will regret using 5200" if it's anything you might ever want to get apart. If you do the two-piece bracket as suggested here, sure you can 5200 one bracket half to the roof and the other half to the solar panel. It isn't an "epoxy" but 5200 poly-something comes close.

Use stainless machine screws and nylock nuts, too. I installed vent covers with the supplied hardware which was stainless but with flat washer, lock washer and standard nut. Nearly all have come loose.

Stainless self-tapping "sheet metal" screws for the roof too, if you decide on screws there. Adhesive/Sealant should keep any water out, but if the threads ever rust, all you have is a small nail into an oversized hole.

[CA_Traveler]

You will regret using Z brackets when you want to access under the panel for any reason. Cut 2 pieces of angle aluminum from HD and bolt them together in a Z pattern. Easy to remove that bolt.

I used screws, VHB tape and Dicor.

[DAS26miles]

Roof is thin fiberglass maybe 1/32”, 1/8” Luan plywood and 2-3” styrofoam. Not a lot for the screws to grab. If there are struts, I can’t find them.
Only 3/4” gap between panel and roof. Maybe I can get a wrench in to loosen the nut, but they are lock nuts.

[DrewE]

Will you be able to remove the panel if you need to?

If I were doing it, I would just use screws and cover with Dicor or whatever, the same as is done for the vents and TV antenna and other things mounted on the roof.

[Ski_Pro_3]

I used adhesive and skipped the screws. Holding fine now for 3 years running. I inspect regularly and I'm sure I'll notice if one or two brackets start coming loose before a complete failure.

However, if you are going to use screws, attach everything first, then take it apart and apply the adhesive so the stuff will go down into the hole with the screw, thereby sealing any leak at that point. There isn't a real need to encapsulate everything in adhesive if the point of entry, the screw hole, is filled with adhesive as the screw goes in as that's where any moisture can possibly do any damage.