Installing Solar on a Pre-wired Four Wheel Camper Shell

Four Wheel Camper – to my knowledge – pre-wires every camper they make for solar. Their wiring and polarity match that of Zamp products – which is what they install at the factory. The video below walks through the basics of what’s required. My experience varied from what’s outlined in the video… hopefully my trials and tribulations documented below help some of you out in the future.

When I embarked on this project – I was after a few more nitty-gritty details which I had trouble finding. Hopefully the specifics of an install on a shell model here help some of you out.

First, the controller location. For those of you without solar from the factory – it looks like pretty much every camper out there has a “plug” where the controller would go (a random square piece – like a drawer without a handle – somewhere near the batteries). And that plug covers a holes that fits the 30 amp controller from Zamp perfectly for a flush fit. On the shell, it’s on the rear furnace/stove area and attached from the inside with two screws. I had no way of removing those screws – so a very careful process of using shims and pry bar I was able to remove the plug with no damage.

In my case – our shell has both a furnace and a flush-top stove. Which meant there was a horizontal “shelf” that separated the two compartments and prevented the controller from recessing into the hole far enough to be flush mounted. I used a top bearing flush cut bit on the router to remove about 3/8″ of depth needed for the controller to fit with the wiring. Thanks to my carpenter friend Rob for that idea!

Next, I pulled out all the factory wiring in our battery box referenced in the video above for the solar install. It was bundled in our battery compartment. From there I was unable to get the wires needed routed to the controller. So I placed the new 10 AWG wires in a 5/8″ loom and drilled a hole from the battery box to the controller and feed the loom through. (Picture below)

Zamp recommends an inline fuse between the controller and its connections. I went with two 40 amp breakers that I also installed in the battery compartment.

With the wiring run – it was basically a matter of terminating connections and reconnecting the battery to see if it worked. And at first, it did not. After some troubleshooting and a call into Zamp (who was awesome!), I was able to determine that the wires FWC supplies as part of the pre-wire and mentioned in the video that should run from the controller to the batteries – did not have any connectivity to the batteries. (In my case, the wires look just like the video and run into the main harness at the back of the controller… no idea where they go from there – except to nothing connected to the battery.) So I created my own wires to run from the breaker/controller to the batteries. And viola, the controller fired right up.

It’s also worth calling out here that the FWC pre-wire has a three-wire push-in connector for the negative and positive leads from the panel plugs. But there are only two panel plugs (thus there should only be two wires). In the video, they mention that the wires are labeled (mine were not) and that the third wire would have a loose end to make it easy to wire into the controller (again, mine was not). So without some fancy equipment to figure which wires actually went to each plug, I wired in all three wires to the positive and negative connections. The positive I cut the push-in connector off, and swapped them for ring terminals that mounted to the breaker. The negative I also cut the push-in connector off and replaced it with a four-wire connector to include the line from the controller.

Fortunately, my wiring fiasco ended here. The plug on the roof seemed to work just fine when I test fitted the Zamp panel.

So the last step was mounting up the solar panel. The FWC roof is about the thickness of a pop-can. This led me on a mission to figure out a way to connect the panel that wouldn’t rely on the pull-out strength of a fastener. And eventually led me to 3M VHB tape. 4941 is what I ended up ordering after reviewing 4950 and a few others.

That however, did not go so well. 3M states that 4941 needs four square inches of adhesion for every pound of static load. And while you can find a bunch of “YouTube experts” claiming that just a dap of this stuff on the solar panel feet (maybe four square inches combined) holds their panels on fine flying down the freeway at 80 MPH with crosswinds – I decided that I wanted no less than 100 square inches of tape for my 25 pound panel.

I used 1-1/2″x1/8″ aluminum square tubing and flipped the Zamp feet upside down. So the part that is supposed to be mounted to the roof was facing the sky and the backside was mounted to my tubing. That gave me the full run of the tubing as a contact/adhesion point and also made for removing the panels in the future much simpler and easier.

This plan was quickly foiled however. In addition to the roof of the FWC being paper thin – it’s also about as flat as the Rockies. It was clear when mocking the panel up that maybe 50% of the VHB tape was going to make contact. So that plan and the $50 roll of tape went out the window. Instead, we found the supports in the roof (they are where the wood trim is inside) and used 3M 5200 fast cure – in generous amounts – to act as the primary adhesive. To pull the tubing down to the roof and “clamp” the structure in place we used four small stainless sheet metal screws from the tubing into the roof supports. The ends result is permanent, water-tight, and much stronger than the VHB bond would have been. I can grab and shake the entire truck by the panel after the mount cured.

The last step was cutting and cleaning up the connection from the panel to the plug. Split loom and adhesive backed cable clips keeps anything from rubbing the roof and some dielectric grease and poly sealer on the plug should keep that connection in great shape and water tight.