solar panel screw length

[BobC]

Originally Posted by rvbud

I installed 3-160W panels a couple of years ago on my '08 Sightseer 29R. Winnebago will send you a roof diagram with your VIN no. Yes, there are electrical runs and structural supports that run through the roof. I used 1-1/2" X 1/2" expansion (rubber) nuts with stainless steel machine screws. Simply drill a hole only deep enough to break through the fiberglass skin (no deeper), fill hole with Dicor non-sag, insert expansion nut and screw in the bracket (enough to 'mushroom' the expansion nut), cover top of screw cap with Dicor. Should you ever need to modify the point of attaching, remove the expansion nut, fill the hole again with Dicor and insert a cap plug.

Just to clarify, the hole should be drilled through the fiberglass skin and the underlying 1/8" plywood. The fiberglass is only 1/16" (or less) thick and has no structural strength. From a practical standpoint it would be almost impossible to just drill the fiberglass.

I also agree with AJMike that Dicor isn't intended for fiberglass roofs and you're better off using Winnebago's specified Nuco 311.

[pobstlmo]

Why not wait till you go south to warm weather and then tape or glue them on?

You might want the panels and the roof the same temperature before mounting.

[rvbud]

Originally Posted by BobC

Just to clarify, the hole should be drilled through the fiberglass skin and the underlying 1/8" plywood. The fiberglass is only 1/16" (or less) thick and has no structural strength. From a practical standpoint it would be almost impossible to just drill the fiberglass.

I also agree with AJMike that Dicor isn't intended for fiberglass roofs and you're better off using Winnebago's specified Nuco 311.

Bob, you are correct...never add Dicor (or any other sealant) where Nuco 311 (or any other silicone-based product) has been used without completely and thoroughly removing the residual silicone. However, if you have clean fiberglass-to-metal contact, such as mounting solar panels to your WGO roof, Dicor is fine (according to Dicor mfg specs ... https://dicorproducts.com/product/ep...ealants/#specs). I have found that Dicor remains pliable even after strong sun exposure and has very good adhesion. Same goes for SuperFlex branded products. Research and know what sealant products you are working with.