Locating roof crossbeams for solar panel install?

I am Yu wrote:

chr$ wrote:
Yes, I drive 80 with my TT, so there. Let's not make this a thread about tires. :p

Or about gas mileage ;)

Isn't that what happens to all old threads?

chr$ wrote:
Yes, I drive 80 with my TT, so there. Let's not make this a thread about tires. :p

Or about gas mileage ;)

I screwed mine into the roof where the Z-brackets landed. A few screws hit a joist, most did not. It's more important to mount the brackets on the panels where the panel MFG requires it.

A good amount of Dicor gooped under the bracket and then over the top also does a lot of the work. My first trip out this weekend, 80 MPH on the highway for 300 miles and all was fine. :)

Yes, I drive 80 with my TT, so there. Let's not make this a thread about tires. :p

Solar ROCKS!

This is slightly off topic. I used to be a helicopter mechanic in the Air Force. At one point, we had some hardware that we didn't need any more, and I was told to throw it in the trash. In that pile of hardware were some aircraft-quality electrical toggle switches, and, well, I decided to keep those rather than throw them away. I found projects of various kinds to use them in.

I decided I want a switch to turn my solar panel on and off. After 10 years, I have no more of those aircraft switches, so I went down to Advance Auto and picked up a toggle switch. When I got home and opened the package, I was much amazed, yes sir, at the cheapness of the material and workmanship of that Chinese-made switch! Maybe I'll have to find a source for some aircraft switches for my truck and trailer projects...

I took off the roof vent trim piece inside the trailer, and here's what it looks like inside the roof:



I was able to stick a tape measure in above the insulation, and found the rafters are spaced 16 inches apart. Marked that off on top, and I could get one of the two screws in each bracket to go through a rafter. Used wood glue on the threads of all screws, and self-leveling roof sealant between the brackets and the roof, and over the screw heads. Hopefully that should do it :)

There are several different ways that trailer roofs can be built - you'd best know how yours if built before starting. (Usually this is in the brochure.)

Some are framed - for those it's usually pretty easy to find the trusses by just pressing with your foot and feeling for the spots that don't give, then feel to either side to estimate where the center is.

Some are laminate - you can mount it pretty much anywhere. Under the rubber will be a layer or two of very thin plywood glued to foam. These roofs are generally quite strong and will hold anywhere.

I'm sure there are other ways to make a roof, but those are the two I'm familiar with.

most rv roofs use 3/8 OSB not plywood for the roof decking. DO NOT assume your screws will hold in OSB fin the truss.

I used four 6" long Z brackets with three SS screws per bracket (making a total of 12 screws per panel) and lots of 3M 4200 adhesive/sealant under the Z brackets.

And didn't pay much attention to finding the rafters, was rather more concerned that the Z brackets were properly placed along the solar panels (so the panels wouldn't bend and flex much), and with panel placement to reduce shading by the A/C and vents.

So far, several thousand km's later, no problems.

I'm installing 4 100 watt panels this weekend and I haven't decided whether to use 3/8ths well nuts or just go with some stainless screws into the plywood.

Not concerned about panels pulling off roof, remember your using Dicor under all the pads as well. You could could probably get away with just the Dicor, maybe :-)

I'm not even looking for the cross braces.

Plenty of people have even used that 3M sticky tape ALONE....the only problem with that is I'm not crazy about how Keystone glued the roofing material down to the plywood. I can see the panels staying on the EPDM roof all right but under load the rubber roof could pull away from the plywood.

Good luck

Ron W.

My stainless deck screws are holding my large panels just fine.
Otherwise get to Home Depot and buy a stud finder.