Every season we watch hundreds of RVers roll through a nearby solar panel seller’s work area. Not only do they buy panels and associated parts, they hire the outfit to install the stuff. Mounting solar panels is not rocket science. Any RVer with fair-to-middlin’ skills can probably install solar panels. Rather than present a step-by-step “how to install,” we’ll point out a few of the technicalities.
Wire Runs—From Inside to Out
Running wires from inside the RV to the roof is usually a snap. It’s best to be close to your battery bank storage area. In a couple of our rigs, this meant simply routing our wiring through the roof vent for the RV refrigerator. In our most recent installation, the fridge was on the opposite side of the rig from the battery compartment. Someone had already installed a single solar panel on the roof, and they ran the wire over the rig’s outside skin, adhering the wire down to the rear of the trailer with gobs and gobs of sealant. What a mess!
Since we were going to paint the trailer anyway, we simply yanked the wiring loose and cleaned up the sealant as best we could. Oddly enough, running right through the battery storage compartment was a plumbing vent pipe. By boring a hole in the pipe we routed the wiring up the vent pipe to the roof level. At the roof, we blew another hole in the side of the vent cap, smoothed the jagged edges down, and ran the wire out to the roof through the hole. With the wire in place, you can seal the hole around it in the drainpipe with an appropriate sealant.
Panel Mounting Pains
If you don’t plan on tilting your solar panels, the simple L-shaped panel mounts are an easy installation. You can buy these from solar suppliers, or even simply cut them from aluminum angle stock, available at big box hardware stores.
It’s important to get a good seal against the weather. We goop the daylights out of the roof-contact side of the mounts before running screws into the roof decking. With an EPDM rubber roof, remember to use only compatible sealant: an example of this is Dicor’s lap cement. A spot of sealant over the top of the mounting screw will keep the weather from ever chasing the threads down, but with plenty on the base already, that’s probably overkill. We’ve seen some who use neoprene washer-equipped screws.
If you don’t have a solid roof deck surface to run the screws into—for example, you’re working with a metal roof—then you’ll need to go a step farther and use an insert screw, sold under trade names like Well Nuts. This is a two-piece rubber insert with screw conglomeration; first you drill a hole through the roof material, and then insert the rubber expansion plug. Tightening up the screw expands the rubber insert, giving you a firm support. No need to worry about sealant with these guys, the weather is barricaded out by the plug.
When you go to blast the screws through the panel mount into the side of the panel, make sure you keep the screws well below the working surface of the panel. We’ve seen one sorry RVer who blasted a screw too close to the sunny side of his panel and into the electronic workings. That’s an awful expensive mistake to make.
Across the Roof—Wires and Panel Layout
If possible, follow the master electrician’s adage of running the wiring parallel to building lines. We’ve tried securing solar panel wiring (which should be UV resistant rated) to RV roofs with lap sealant. The idea is to lay the wiring down in a small puddle of the sealant and hold it in place with a piece of duct tape until the sealant cures. We met with rather limited success, but some professional installers swear by the method.
At the risk of additional holes in the roof, our happiest outcomes have been by using wire clamps, like the Noble Wire and Terminal #2216, an insulated model. While the wiring sheath doesn’t need the extra insulation, we like the rubber coating on the clamp as it won’t chafe against the insulation and possibly cut into it. We simply open the clamp, place it around the wire in the desired spot, then close it, and run a screw through it. Since the hole in the clamp is a bit big, we use a small washer to keep the screw down to a small size. After we’ve installed the clamps where we want them, we run a dab of lap cement over the top to keep the weather out.
If you have acres of space on your roof, locating panels isn’t a big deal. We try to keep ours away from nearby objects that might cast a shadow on the panel: Think TV antennas and satellite dishes. Again, we usually try to run the panels parallel to the rig lines, the long side of the panel to the side of the rig to reduce wind resistance. That’s not always possible, so in the photo you’ll see a smaller panel somewhat shielded by a bigger one, with the smaller one running 90 degrees out of phase with the “recommended” way.
Of course, a few other technicalities should go without saying: Always ensure the safety of your body and your RV by carefully setting up your ladder. Since RV roofs can be delicate things, it’s best to use “walking boards” when up on the rooftop. These boards should cross over rafters at both ends and in the middle to evenly distribute your weight onto substantial roofing members.
Russ and Tiña De Maris are authors of RV Boondocking Basics—A Guide to Living Without Hookups, which covers a full range of dry camping topics, and of Camp Hosting USA-Your Guide to State Park Volunteering. Visit icanrv.com for more information.
I appreciate your tip to run wiring for solar panels on caravans parallel to the lines of the caravan. I think it’s easy to forget on something like a caravan that you ought to follow similar guidelines as you would follow on a building with solar panels and other such devices. I’ve heard that there are different types of solar panels that withstand the weather the best that are ideal for mounting on caravans.