What's the best method in securing solar on a rubber roof trailer? This will be a flat install. Z-brackets are already ordered, but if there's something better...It is for my son-in-law's new toy hauler.Sal

Hi Sal,I'd make ever effort to find the "rafters" and screw into them, using liberal amounts of dicor. That is how my panels are fastened. I used three screws per side with angle aluminum to "stiffen" the panels. If it is a new unit the maker should be able to provide measurements for the rafter placement.I hope your son is excited!

I always thought those single screw Z brackets were pretty iffy. I made my own using 1/8"x2" Aluminum Angle Iron 2" wide each. 2 SS screws into each at roof, drill 1/4" hole in side of solar panel frame and use 1/4" SS bolts to the angle iron.

ISTR Almot keeps posting that Z brackets are no good, you need L brackets or whatever they are.If you have access while on the road, here is that members' installation examples collectionhttp://www.rv.net/forum/index.cfm/fuseaction/thread/tid/25705772

Make an effort to have them a bit slanted to shed water.See signature for mine. z brackets are probably better.

Yes, I keep posting it because it's true. Z-brackets are made for shore homes, to be installed permanently on the rails. In RV you need to be able to get under the panel for cleaning, and you WILL have to do a roof rubber replacement or re-coating at some point. With Z-bracket bolted into the panel frame bottom and #10 screws through the foot of the Z into plywood, the only way to remove the panel is to rip #10 screws out of the ply.Use L-brackets instead. 1/8" aluminum angle 2x2, 3x3 or 4x4, 6" long. Drive two or three screws #10 into the ply, with plenty of roof sealant under the bracket and over the screw heads. One machine screw goes into the side of the panel frame at each corner, you might need stainless rivnuts (aka nutserts) in the frame if you can't get under the panel - 2x2 angle leaves about 1" gap. With 3x3 angle you can insert machine screw or clevis pin from either side, no rivnuts required. Check installations by Mr.Wizard and Bigfootford in the link above. Mr. Wiz used a double-sided sticky tape under the bracket because his roof is fiberglass, but on the rubber you need a roof sealant. Short vertical "legs" of Bigfootford you don't need if you don't plan on tilting, though they are handy to raise the panel higher and to insert machine screws in the frame without using rivnuts.To hit the rafters with #10 screws - you may try. Luckily 120v panels have - usually - 65" length and most rafters are on 16" centers, so this is possible. With a flat mount and 3 screws in each bracket I don't think this is necessary though. Roof normally has 1/2 or 3/8" OSB (kind of a particle board), or occasionally a real plywood. So you don't need screws longer than 1" if you don't hit the rafters. If yo do, you will need 2"-2.5" screws. If your manufacturer is still in business, phone them and ask to email you the drawing of roof assembly where it shows rafters. Just tell them the truth that you are installing solar panel.Slanted to drain the sand and water off - if you install panels lengthwise, with panels on the slopes, i.e. panel doesn't cover the crown of the roof, with brackets of the same height the panels will automatically become slanted.

Mounting solar on rubber roof | Good Sam Community

23 Replies

ken_white
Explorer
Nov 06, 2013
Salvo wrote:
Thanks, those were the exact ones I'm been looking at. They are not neoprene though, but rubber. I got 3/8" plywood roof. They will fit. I just don't like the thought of drilling a 1/2" hole for a 1/4" screw.

You use 2 per bracket?

I don't think there's any issue with the styrofoam insulation compressing when torquing down the well nut.

McMaster also carries them.

Sal

They are actually made of Cloroprene rubber, which is neoprene.

I used two bolts per mounting bracket (angle aluminum) for my 190 watt panels on my other 5th wheel and one bolt per bracket for the 50 watt panels on my truck camper due to size.

McMaster is normally my first choice for hardware, but Grainger is right down the road if I need it quick.

:)
Salvo
Explorer
Nov 06, 2013
Thanks, those were the exact ones I'm been looking at. They are not neoprene though, but rubber. I got 3/8" plywood roof. They will fit. I just don't like the thought of drilling a 1/2" hole for a 1/4" screw.

You use 2 per bracket?

I don't think there's any issue with the styrofoam insulation compressing when torquing down the well nut.

McMaster also carries them.

Sal

ken white wrote:

I used these -> 1/4-20
ken_white
Explorer
Nov 06, 2013
Almot wrote:
Salvo wrote:
A couple used well nuts or molly bolts. This attachment is more secure, especially when no rafters are available. Can the styrofoam insulation behind the plywood inhibit or degrade this attachment method?

Never tried. What - I'm afraid - may happen is that after you've fastened it and the rubber had forced its way into the foam, the foam remains under pressure and will give in some more, with time. So it might need more tightening later.

You might be correct, my roof did not have a styrofoam backer, it had regular insulation behind the plywood roof.

I did check my bolts at the beginning of every season when I checked my roof, and did snug them if needed.
ken_white
Explorer
Nov 06, 2013
Salvo wrote:
Ken- what size thread did you use? Perhaps 10-32?

Where did you purchase them?

Sal

I used these -> 1/4-20

You just need to make sure the grip length (range) is sufficient for your roof.
Almot
Explorer III
Nov 06, 2013
Salvo wrote:
A couple used well nuts or molly bolts. This attachment is more secure, especially when no rafters are available. Can the styrofoam insulation behind the plywood inhibit or degrade this attachment method?

Never tried. What - I'm afraid - may happen is that after you've fastened it and the rubber had forced its way into the foam, the foam remains under pressure and will give in some more, with time. So it might need more tightening later.
Salvo
Explorer
Nov 06, 2013
Ken- what size thread did you use? Perhaps 10-32?

Where did you purchase them?

Sal
mena661
Explorer
Nov 05, 2013
Looks like I'll go with well nuts and L brackets. Thanks all (Salvo).
ken_white
Explorer
Nov 05, 2013
I used neoprene well-nuts for my previous 2 installs and will use them again for my new 5th. Make sure the roof area is clean where they get inserted so they don't spin and then apply Dicor overlapping the well-nut edge and roof area.
Salvo
Explorer
Nov 04, 2013
Looking at all the installs, it appears, most people use screws to secure brackets to roof. A couple used well nuts or molly bolts. This attachment is more secure, especially when no rafters are available. Can the styrofoam insulation behind the plywood inhibit or degrade this attachment method?

Bill Rhino has a good video installing a panel with z-brackets. It doesn't look like an optimum design. You can't remove the panel without removing the roof screw & bracket. There's not much of an air gap between roof & panel either.

Sal
SCVJeff
Explorer
Nov 04, 2013
L-Bracket