Hey everyone, first post here. This forum has been a great source of info for me. So I’m looking to install some solar panels on my 2006 Four Winds Express Lite. Until now I have had just one panel mounted on a portable stand but I’ve decided to add at least one more panel and I don’t want to be dragging two of them around.My question is, when I mount the panels on the roof i’m assuming I want to try to screw them into the trusses right? I don’t know how thick the plywood material is so i’m a little leery about just screwing into the plywood. So assuming I do want to hit the trusses, what is the best way to find exactly where they are? I think I can see them indicated by the lighter spots on the roof (see pic) but I want to be sure before I start drilling. I’ve tried a magnet but it doesn’t want to stick to anything. Maybe I need a heavier duty magnet. I’m guessing the trusses are a ferrous metal and not aluminum or wood right? Anyone have the spec on what the truss spacing is on this particular trailer?Thanks

Before assuming you need to do that, determine the thickness of your plywood. Mine's only maybe 1/8" and 8 big wood screws hold my panels just fine.

Is there a soft spot next to the edge of the roof line?

Wood is used a lot. Remove ceiling fixtures and probe for trusses. I could actually see mine. VHB tape and screws should hold. Advice: Z clips make panel removal difficult. Use 2 pieces of Al angle bolted together. Stainless screws and bolts.

I didn’t notice any soft spots but I wasn’t looking for them. What would that tell me? I will try pulling some fixtures and see if I can locate any trusses, good idea. And if I don’t worry about hitting the trusses how can I tell the thickness of the sheeting? I know I’m probably making this more complicated than it needs to be but want to do it right the first time.

I indiscriminately put the screws through whatever my roof is made from and some sealant over and under that. They haven't blown off yet. Don't overthink it.

Solar Panel Mounting Advice Needed | Good Sam Community

17 Replies

TechWriter
Explorer
Jun 23, 2019
Very nice. Kudos!
RBREW
Explorer
Jun 23, 2019
Got the panels mounted today. It was actually pretty easy. I don’t think I hit any crossmembers but the panels are still very secure. I have no worries that they will come off. Thanks for the tips guys.
RBREW
Explorer
Jun 09, 2019
Ok, sounds like I shouldn’t worry too much about the trusses. I’ll definitely lay down some eternabond and cover it up with some dicor.
grizzzman
Explorer
Jun 09, 2019
RBREW wrote:
I didn’t notice any soft spots but I wasn’t looking for them. What would that tell me? I will try pulling some fixtures and see if I can locate any trusses, good idea. And if I don’t worry about hitting the trusses how can I tell the thickness of the sheeting? I know I’m probably making this more complicated than it needs to be but want to do it right the first time.

because there is a solid point just past the soft spot, about 1.5 to 2" on the roof on the last two RVs. I made my mounts 5" long with 4 screw holes. used polyurethane sealant. Have had 45 mph side winds at 80 mph speed. no issues.
Itinerant1
Explorer
Jun 09, 2019
My installer used aluminium angle pieces screwed into the roof with the about 1.5 inch space from bottom of panel side to roof, it's been 3+ years and 25k miles no signs of leakage or loosening. The roof decking is 1/2" plywood if that make a difference for stability.

Adhesive tape is suggested often and seems to work well if it's a fiberglass or aluminum (solid surface) roof but if it's vinyl style what stops it from lifting without screws?
KD4UPL
Explorer
Jun 09, 2019
It's highly likely that your trusses are wood or maybe aluminum. I don't know that I've ever heard of an RV having steel roof trusses.
Your 14" x 14" vents are located between the trusses. That is the easiest way to find them. That's probably why the standard vent size is 14", it fits between trusses spaced at 16" on center.
I've installed panels on several RV roofs, I've tried to get some screws into the trusses if possible but mostly they just land where they do. Add some 3M tape and Dicor sealant to that and I haven't had problems.
westend
Explorer
Jun 09, 2019
I used a similar mantra as Techwriter when attaching 235 W panel but I used aluminum "U" channel because I have a tilting mount, I determined truss interval (I have wood) by measuring back from a vent opening 16" OC. I drilled the aluminum and through the metal roof into the roof truss. I then fastened through a piece of Eternabond tape, (3) #12 metal screws through each "U" channel and into the (3) trusses. The Eternabond tape seals the screw as it is driven and the #12 size insures against any movement.
Good luck with your install.
Lwiddis
Explorer II
Jun 09, 2019
“So I’m looking to install some solar panels...” After an energy survey determining what you need for current AH use or what you want to use? (One solar watt per adequate battery AHs minimum)

I drive lots and have yet to see a blown off RV solar panel. As said above, don’t over think this.
TechWriter
Explorer
Jun 08, 2019
I first screwed down a 2" aluminum strip on either side of my panels. Then I fastened 4 aluminum L-brackets to the strip and to the solar panel.

Like so . . .
Ed_Gee
Explorer II
Jun 08, 2019
No professional installer I have ever heard of that tried to hit trusses.....just screw into wood substrate. Thousands upon thousands of RVs have it installed this way with no problem. Personally I would rather not screw into roof at all so I installed my panel mounts with 3M VHS doubleside tape.This seems to be the way more and more installers are doing it.

I sure agree with the guy who suggested not using the common Z mounts.....they make it very difficult to remove panels ifneed be.