Solar installation on TPO roof on RV

[GordSanClemente]

Hi All,
DIY Solar provides some great information on options on mounting panels on different types of roof materials.
Found here...
https://www.mobile-solarpower.com/solar-panel-mounts.html
The page never mentions TPO type roof. I imagine it should be treated as being similar to one of the types discussed.
I searched "TPO" in this forum, and got zero results. (hopefully did it correctly)
Anyone have some thoughts on what it is close to, if anything?
I think it would be helpful if you could site some basis for your assumption. (for me and anyone else reading this discussion)
Thanks in advance,
Gordon

 

[KG6S]

It is most similar to EDPM "rubber membrane" roof material like I have. Best use a Z type bracket with lots of Dicor self leveling sealant. I made the brackets so I could pull the panels without disrupting the roof side seal. I came back and added an extra layer of Dicor after this picture was taken.

 

[GordSanClemente]

Thanks for the picture!!

 

[atatistcheff]

I made the brackets so I could pull the panels without disrupting the roof side seal.

I'm getting ready to mount a couple of 100W panels on my 2004 trailer with a rubber roof. Seems pretty straightforward so far, just some screws and lap sealant plus maybe some eternabond tape. Just a couple of questions based on your experience.

1. Type and length of screws? I assume stainless steel is best to avoid rust. What about the length? Don't want screws coming through the inside.
2. I like the idea of being able to remove the panels and leave the mounting brackets on the roof. Can you elaborate a bit on how you modified the z-brackets to do this?

Thanks!

 

[KG6S]

I used #10 X 1-1/4" Stainless Indented Hex Washer Head Screw, (25 pc), 18-8 (304) Stainless Steel Screw by Bolt Dropper from Amazon to attach the brackets to the roof. I have 5/8" solid plywood under the EDPM roof, so I figured over penetration through the plywood, EDPM, and bracket would not be much of a problem. I intentionally did not use self tapping screw so I could maximize the grab of the threads into the plywood. Drilled undersized holes, filled with Dicor lap sealant, put Dicor under the brackets and on top of the brackets.

For the brackets, I used two 1" angle aluminum into a Z configuration. One angle attached to the roof, the other to the panel. All fasteners are stainless to eliminate galvanic corrosion with the aluminum. I've attached a zoomed in photo for your viewing pleasure. Also, I need to loosen the center brackets from the panels and re-attach on the panels mounted across the roof right to left, because I didn't take into account that the roof is slightly crowned. The panels handled it thus far, but I don't want them to stress.

 

[KG6S]

I forgot to add that I also used #10 Neoprene EPDM Bonded Sealing Washers Stainless Steel 18-8, Neo Bond, 100 Pieces (#10 NEO Bond Washer) under the head of the screws further decreasing roof penetration. I wanted something a little compliant that would flex a bit but still retain a good seal around the screw head.

 

[atatistcheff]

Thanks for the details, that looks like a good way to mount these without breaking the bank or drilling extra holes in the frame. I have some of that angle aluminum leftover from a previous project that I can put into service.

 

[GordSanClemente]

Atatistcheff, glad you asked these questions!.
KG6S, based on the curve of your roof, did you think that maybe 1 1/4 or 1 1/2 might be a better choice for the edge brackets if you had to do it again? Clearly this will get me measuring the bow in my roof.

 

[KG6S]

Atatistcheff, glad you asked these questions!.
KG6S, based on the curve of your roof, did you think that maybe 1 1/4 or 1 1/2 might be a better choice for the edge brackets if you had to do it again? Clearly this will get me measuring the bow in my roof.

That's probably a good idea! I would also like to have a slotted panel bracket to adjust, but I don't have a mill to do that. I'm going to release the allen bolt and re-drill and hope for the best.