Mounting solar on roof 2003 Journey 23TD?

[fthunder]

Howdy! I've been digging into my solar plan for our RV for about a year now and have a solid plan together. I found three 400W solar panels on sale at a place in Phoenix. They are large house panels that are about 4' x 5' in size, 47 pounds a piece - but my roof doesn't have much on it so there's plenty of room.

My original plan: Firstly, I have that rubber membrane on the roof so double-sided tape wouldn't work in my case. I had read in a few places that there are studs that run from port to starboard in the roof - definitely around skylight(s) and fan(s) already there, but I cannot find a stud finder that lets me find them. I was going to put some strut channel down the roof, but not sure if that's the way to go now.

Being a DIY, I broke down and called the RV repair shop. The service guy talked to a tech and the tech (who has probably worked on my RV) said that the roof has 5/8" plywood and as long as I use at least 1 1/2" coarse thread screws, I can mount the solar panels anywhere on the roof. Just as long I put dicor on the threads and then more dicor on the screws.

And then I saw a cross section of a Class C RV where it was just fiberglass and foam under the roof. Obviously I don't want to screw into just fiberglass and foam; I don't think that would hold well even with the dicor.

My nexts steps were to ask here, and then maybe pull off the inside of one of the fans and see if I can push a bore scope in a hole I can find to take a better look? Any ideas?

 

[Pointyears]

Your're going to have to drill for the cabling to go through the roof, no? Won't that give you a better opportunity to see what it's actually composed of?
Have you checked online with Winnebago to see if they have structural plans for your roof?

 

[Gizmo1137]

Yes definitely check with Winnebago who has been very good in sharing structural, information as well as schematics, wiring and plumbing diagrams. Then as Pointyears suggested, drilling your wire entry hole would give a good idea as to how the roof is constructed.

 

[Morich]

One of the problems with getting info on how an RV is built is that the answer changes with every different RV and each year, make, model may be different!
A 70's, 80's or any given time frame had different methods and each brand did the same.
Even a quick look at how a Winnebago trailer is built will show it may be different than their motorized! Over the years, framing has gone from totally wood to various forms of met and some are now boded structures with little internal framing.

When you ask, the answers may be totally honest from that person's experience. But is what they have dealt with the same as what you have?

So you need to ignore much of those ideas and find out what YOUR Rv has as what they had means very little that I would trust!

I recommend first trying to get good reliable info from Winn as they do have the plans and you may get good info there. results may vary but some get good stuff?

Stud finders may have varied degrees of success as it can be very tricky to get a reaction if the framing is wood and your sensor is looking for metal, Trial and error?
Pulling some fan covers inside can give an idea of what the overall makeup of the roof might be. One way to get a bit of idea on what materials any cross members might be is to force a dowel rod or long metal rod into the foam you may find. If there is a cross member and you push/pull the rod, you may hear it thump into wood or get a different sound from metal.
If you have located a cross member in the ceiling, then you can move to other tools by checking how that tool reacts to that cross member.
If you know where the item is for sure, you can then learn how to find it with whatever tool you are using. After finding what it takes to find the wood, metal or whatever, then you can move to finding others!

If you can get good info from Winn and find one, then you can go for finding others with more confidence!
Lots of different tools out there for the search but we each need to learn the basics of what the tool may tell us.
Not good to go by what a metal detecting stud finder says if it might be following a wire instead of framing!

 

[fthunder]

Thank you for the info - yes, absolutely knowing that the roof composition between RV roofs even within the same year is what drove my fears to ask around and not just go with the first answer I got from the RV techs. I did contact Winnebago and they took my VIN and were able to give me the following information:

For my particular 2003 Journey 32T DL
The first layer under the fiberglass is a 1/4" piece of Luan which I had to google and find that that is wood. Directly under that is a 3" piece of styrofoam with channels that run wiring back and forth. Winnebago suggests that I mount the solar panel mounts to larger panels around 12" square, VHB tape on the panels and since I have the rubber membrane, some shorter coarse thread screws.

Edit: Yes I do have to drill a hole for the wires which I plan on doing in a hollow place / wall between the bathroom and kitchen that had a lot of wires and plumbing already within. I wasn't sure if that part of the roof would be the same.

 

[MadMaxWinny]

I have the same vintage RV. I used "well nuts" and 3M 4200. I ran the 8 AWG cable down the refrigerator vent which gave a clear shot to the chase at the floor level.

 

[Sierradave-WO]

I did the same as MadMaxWinny for my 2006 33v Adventurer.

 

[fthunder]

How did you guys use well nuts?
I would imagine I'd drill holes that are large enough for the well nut to fit into, maybe like 3/8"?
I would imagine I'd have to drill through both the fiberglass and luan, but I don't want to drill into the styrofoam too far; Winnebago said there are chambers in the styrofoam that run wires so I'd have to be careful.
Also do you think the rubber membrane would cause issues with well nuts?
I found these that come in varying sizes: Amazon.com

 

[MadMaxWinny]

I used #10 x 3/4". No issues. I did hit a metal support (twice). They are not that thick and if anything, it provided more strength to the mount.

Amazon.com

 

[Sierradave-WO]

How did you guys use well nuts?
I would imagine I'd drill holes that are large enough for the well nut to fit into, maybe like 3/8"?
I would imagine I'd have to drill through both the fiberglass and luan, but I don't want to drill into the styrofoam too far; Winnebago said there are chambers in the styrofoam that run wires so I'd have to be careful.
Also do you think the rubber membrane would cause issues with well nuts?
I found these that come in varying sizes: Amazon.com

The well nuts I used are an expanding rubber washer/threaded nut that penetrated under the luan. I experimented with a sample piece of 1/8" thick paneling. My test confirmed the rubber well nut was a solid anchor for attaching my solar panels with screws. I used 1-5/8" aluminum unistrut channel for a base to attach the solar panels. I drilled four holes per panel to attach the unistrut channel and covered the screws with Dicor self-leveling sealant. I have exposed the panels to at least 80 mph winds with no issues for the past four years. I've uploaded some photos so I can show you my installation. One of the photos shows multiple tests for a variety of hollow-wall anchors in my test 1/8" thk panel. The rubber well nut is the black one. The aluminum well nuts compressed thru the luan, which could fail. I don't trust double-backed adhesive tapes or wood screws through the thin luan. Adhesives breakdown with heat and wood screw can stripout.