Friday, January 4, 2013

Solar Panels on Jayco Travel Trailer

During the holidays, I outfitted our new Jayco Jay Flight 28BHS travel trailer with a new battery and solar charging system. This modification will allow us to do more extensive boondocking without dragging out the generator.

The Plan

I expect we will run lights, fans, vents, furnace fan, computers, DVD player, and astronomy equipment off of the batteries. I don't plan on running the microwave and certainly not the air conditioner. I will probably not tie into the existing AC power distribution panel but simply run an extension cord from a small dedicated pure-sine inverter.

I started this project with a lot of reading. The most useful materials I found were:
After much research, I settled on a pre-configured system from AM Solar as the starting point of the project. The technical support provided by AM Solar has been excellent and the components in the kit appropriately sized. I highly recommend them as a supplier. The model I choose is the SunRunner Signature 100/25/8/6/Pro. It is based on the 2512iX charge controller from Blue Sky. I also had cause to contact technical support at Blue Sky, another company that I highly recommend. I had a long talk with the owner who took the time to explain the functioning of the controller in detail. Initially, I got a single GO-100, 100W panel. I will be adding a second panel next week and a third later, if needed.

I also planned to add a small inverter to power our astronomy computers. I chose the GPSW300 pure-sine model from Go Power! It has both a low standby current and, importantly, connections for installing a remote switch.

Finally, I planned to upgrade the existing battery from the wholly inadequate battery provided.

As an additional note, if you are considering a solar system on an RV, realize that you're unlikely to reap any cost savings from such an installation as you might expect from a home installation. Hookups are usually included in campground fees so electricity is essentially free. The real issue not energy savings, it is energy availability. If you are camping away from shore power for more than a day or so, solar provides a clean and quiet way of recharging the batteries sufficiently to make up for the electrical usage necessary for your camping enjoyment.

Part 1 - Battery Upgrade

This is the Group 24 deep cycle battery provided by the dealer ... yikes.

The first step was to rip this out and repurpose it elsewhere. In its place, I opted for a pair of Trojan T-105 6V golf cart batteries. These have a 20hr rate capacity of 225AH. I obtained them from a local golf cart vendor. The difficulty I then ran in to was that space on the trailer A-frame is pretty limited.

As described by other Jayco owners, the battery mounting track is about 1/8" too narrow to fit the new batteries. In order to rework the mounting, I first used two layers of pressure-treated plywood to build up some supports ....

... and then fitted a plywood platform on top, bolting everything through the original metal brackets. Notice that I had to notch around the support brackets for my Equal-i-zer hitch. I also had to move these brackets forward by 1.5" from the ideal 32" placement.

The batteries are housed end-to-end in a polyethylene battery box made by Century Plastics which was recommended by another Jayco owner. I obtained it on-line from All Battery Sales and Service. Others have reported having to move the propane tanks forward to make everything fit. However, by jiggling the box around on the platform, I found a placement that clears both the propane tank cover and the rounded front of the trailer ... barely.

Part 2 - Battery Cable

The next part of the project was to tie the battery to the solar charge controller. I spent countless hours pondering the best path to route cable ... mostly because I was trying to plan this project before we actually received our trailer. Pointless exercise in the end, since the configuration we actually received was not quite what I'd measured on the dealer's lot. We did receive technical drawings for our trailer from Jayco, which is a great service that they provide, but I couldn't request the drawings until we had a VIN for the trailer. Jayco does request that the drawings not be shared.

I finally chose to drill holes in the beam at the back of the A-frame and then to go up through the floor of the front pass-through compartment. I estimated around 20 ft total circuit length and computed a 1% voltage drop at 15A using 4 AWG wire.

I ordered a suitable amount of 4 AWG welding cable, 0.4" thick, from Wire and Cable to Go, another company I recommend based on their responsiveness. Due to an ordering error, I ended up with 4/0 AWG welding cable which is much thicker at 0.75". I decided to go ahead with the project using this cable. It gives 1% voltage drop over 20ft at 100A and would allow brief usage of a 1000W inverter or allow the battery bank to be upgraded in the future. By the way, I am really impressed with how flexible welding cable is, even at 4/0. My cable cutters, rated for 2/0 cable cut through this stuff like butter and make a very clean cut.

Here are the holes in the A-frame with an edge protector inserted into one of them.

The device on the left is a DC breaker that was part of the original wiring. The floppy panel at the bottom is part of the "thermal package" which we ordered with our trailer. Addition of this package made routing wire more challenging. I ended up removing the self-tapping screws that hold this giant panel in place along just the front edge and the first 12 feet of the curb-side edge. Prying down this front-right corner allowed me to access the space between the metal beams. Note that the trailer has another insulated space between the wooden joists that sit on top of these beams. I routed the cable in the lower space created by the thermal package panel. I did not have to drill through any other metal beams.

Crimping connectors onto thick cable was a new experience for me. I got the 4/0 heavy duty ring-terminal connectors shown from Home Depot. I purchased the Pico 0685t Lug Crimping Tool shown from an Amazon vendor. It works by inserting the connector under the metal plunger and banging on the top with a small sledge hammer. Works great and cost about $20. Though I used copper wiring, I decided to use Ox-Guard anti-oxidant on all joints and silicone caulk under the heat shrink tubing.

In addition to wiring the controller to the battery, I also needed to install a fuse and a shunt to measure battery current. Starting with a pair of 4x4 conduit boxes from Home Depot, I created my own access holes with miscellaneous conduit parts. I attached one box to each end of the battery box.

In the first box, shown below, I gathered all of the positive connection points (12V). One large cable goes to the positive battery terminal and the other is routed to the controller board described later. The thin 8 AWG wire is attached to the positive trailer wiring that previously connected directly to the battery. Between the two cables is an ANL fuse mounted on a home-brew mounting terminal made from stainless hardware.

The second box mirrors the first and contains all of the negative connections (0V). Instead of a fuse, the block in the middle is a "shunt," which measures a small voltage drop caused by the total current through the battery. This was part of the SunRunner kit. The small black wire ties to the trailer negative terminal wire. The small grey wire is a twisted pair which sends the shunt voltage measurement to the controller remote display.

This is the top of the box with the batteries in place. An additional 4/0 AWG section links the two 6V batteries. The whole box is a single unit and can be removed as such.

I have also added a battery watering system which I purchased from Camping World. The picture shows the black tubing snaking between the batteries and ending at a quick disconnect at the bottom of the picture.

The final thin black wire at the top of the image is the temperature sensor, included as part of the SunRunner kit, which allows the charge controller to account for battery temperature.

After all was done, I had used 23 ft of the 4/0 AWG cable in this circuit. In retrospect, the job would not actually have been easier had I used the originally planned 4 AWG cable. I am still uncertain whether the sheathing on the welding cable will survive the corrosive environment or whether I will need to rethink that part and add extra protection.

Update 2014-06-08 - Year and a half later, no problems in the battery compartment.

Part 3 - Controller Board

I mounted the Blue Sky 2512iX solar charge controller, a 30A DC circuit breaker, and the Go Power! GPSW300 inverter on a plywood board which I fastened to the back wall of the front pass-through storage area of the trailer.

Here is a detailed view of the controller board.

The standoff terminals are made from stainless steel nuts and bolts. I fully wired the board and then brought it into the trailer for final mounting and connection. I still need to build something to protect the exposed terminals from accidental shorting caused by other items stored in this pass-though.

The two cables labeled Battery+ and Battery- are the ends of the 4/0 cable routed under the trailer. Some care was needed in drilling the holes. By pressing up against the insulation-retention shroud under the trailer I was able to feel where the joists were. There was one running down the center of the trailer, one 18" to each side of center. My holes are within one of these spaces.

The smaller wire bundles labeled "Remote" are the signal wires. The right hole is the bundle from the battery box. This includes (1) the temperature sensing cable and (2) the shunt-voltage measurement cable. The temperature sensor is wired into the controller whereas the shunt-voltage cable loops back down through the left hole along with (3) the remote-switch cable for the inverter and (4) an RJ-45 cable providing serial communication between the controller and the remote display.

Update 2014-03-16 - This past week, I had the IPN-ProRemote display go dead on me. After debugging, turns out to be the serial cable back to the controller. This cable is a flat phone cable with RJ-11 jacks on the ends.  Fortunately, replacing the jacks solved the problem. In hindsight, I would recommend routing a more robust cable like an stranded copper 18/8 under the trailer for the three remote connections (serial control, shunt voltage, and inverter shutoff), terminating that to a terminal block and only running phone patch cable in an exposed area.

Part 4 - Remote and Wiring

As with any electrical project, running wires always seems to be the hard part. Turns out that dealing with the 4/0 AWG cable was the easy part! The next step was to route the cable from the controller board to the remote display. Again, lots of options, none of them easy. Voice of experience ... the space under the refrigerator cabinet houses the fresh water tank (not shown on the technical drawings we received) ... don't drill there! Fortunately, I stopped before puncturing the tank, but I do have a hole in the floor of that cabinet now to remind me of the error.

In the end, I chose to bring the three cables, enclosed in a plastic wire loom, up into the cabinet space under the kitchen sink. This view, with the drawers pulled open, shows where I drilled through the floor with a 3/4" hole saw. I used a sharp metal probe to punch down through the insulation and the protective tarp which holds the insulation in place under the trailer. This brought the bundle down into the thermal package "air space" from which I could pass it across and up into the front storage compartment.

On the outside of the cabinet, facing the trailer entry door, I mounted both the remote controller display for and a big switch to turn the inverter on, since it draws a noticeable amount of power even in standby mode. I traced a pattern on masking tape and cut out square holes with a keyhole saw. The plywood is pretty thin so I glued some pieces of wood inside the cabinet into which to screw.

Here is the controller display and the inverter switch in place next to the existing AC outlet. Note that the battery is charging ... yay! The sun is not actually out this week, so only paltry +0.2A charge current.

Part 5 - Solar Wire Routing

By far the hardest wiring job was getting from the roof to the controller with no visible wires. Due to the layout of hardware on the roof, I choose to mount the panels near the front of the trailer. I also decided not to come down the refrigerator vent as is often done but to use a combiner box from AM Solar on the roof.

I ended up pulling down the lights, speakers and A/C vent covers from the ceiling in the front bedroom and poked around in the ceiling space to figure out where the roof trusses were actually located. These holes also provided a series of places where I could fish the guide-rope that I used to pull the stiff 8/2 cable provided in the SunRunner kit.

My first hop was from the hole under the light fixture ...

... to the hole under the left speaker.

Then a short hop to a hole I drilled in the ceiling inside the left wardrobe cabinet. There are two closely spaced ceiling joists here - I drilled up between them. Because this is near the outer wall and the trusses taper down, there is just barely enough space to fish the rope.

The cable routes from this hole down along the inside wall of the cabinet out of sight. It then goes back into the stud space of the exterior wall through a 3/4" hole at the bottom of the cabinet. I temporarily removed the AC outlet which is under the cabinet to provide another place to continue fishing wire.

Finally, the wire comes back out though a matching hole in the pass-through just above the driver-side pass-through door. The wire then connects to the PV+ and PV- terminals on the controller board.

Back at the other end of the wire run, the hole shown below is in the cabinet above the sink, just aft of the light fixture where I started. The combiner box is on the roof directly above this point. No wire goes though this hole but it was needed to help fish wire from the roof.

Part 6 - Solar Panels and Combiner Box

Now the nail-biting part - drilling through the roof. Just above where I drilled the hole in the kitchen cabinet, I drilled down through the roof center-line at a point where I knew I would not hit a ceiling joist using a 3/4" hole saw. I fished the wire up from the cabinet and sealed it with a wad of butyl tape.

In this picture, you can see the wire cable (grey) coming up through the roof. The combiner box provided by AM Solar fits around this hole and screws down onto the roof, again using butyl tape in the screw holes. The wire from each panel is then wired into the terminal bars contained within the box.

The mounting brackets for the panel itself are all stainless steel. The roof of the Jayco is 3/8" plywood screwed onto trusses made from 2x2. The whole is then covered with the roofing membrane. I mounted the brackets as near as possible to where I estimated these trusses to be for added support.

The brackets are shipped from AM Solar with 3M VHB tape stuck to the bottom of the feet. This tape cannot be used with Alpha-Ply which is textured, so I had to remove it first. I found it easiest to do this by peeling up a corner and then rolling it under my thumb. Once that was removed, I put a layer of butyl tape under the bracket and screwed it onto the roof deck.

Finding an appropriate roof sealant was quite frustrating. The Jayco trailers are now manufactured with a new roofing material from Alpha Systems called Alpha-Ply. I think it might be related to TPO, but I am still not sure. Reference material on-line, including a bulletin from AM Solar, and various forum postings indicated that the commonly-used DiCor Lap Sealant causes bubbling of the Alpha-Ply material due to reaction with the petroleum distillates in the sealant. Sometimes this bubbling is only temporary, but I didn't want to take a chance.

I managed to find at RV Parts Nation a supply of Alpha System 1015 Self-Leveling Sealant which is purported to be compatible with Alpha-Ply.

I used this to seal around the combiner box and over and around the mounting feet for the panel. Note that self-leveling sealant doesn't actually level out that much.

Here is the completed panel including the optional 45 degree tilting bars. Tilted up, you can better see the sealant around the combiner box and over the mounting brackets. As per AM Solar's recommendation, the combiner box lives under the first panel for added protection from the elements.

Note that this upgraded bracket type not only allows insertion of the tilting bar, it also conforms to the slightly domed shape of the roof. Here is the panel in the lowered position which I expect it will operate in most of the time.

The second panel will be mounted just behind the first one. I will leave about 19" clear between the second panel and the A/C unit to ensure that this panel is not shadowed. If I need a third panel, it will go the same distance behind the A/C, also mounted length-wise.

Obviously, the TV antenna will have to stay down while the panels are operational since it shadows pretty much every spot on the front end of the trailer. Not a big deal for us, since we don't even have a TV in the trailer.

Update 2013.01.13 - Installed the second solar panel this weekend about 6 in behind the first with plenty of clearance to the A/C unit.


  1. Excellent report. I have studied it closely because I've been contemplating a similar project for our 2011 27' Komfort Trailblazer. One question: in your section on 'Solar wire routing', you said:

    "The cable routes from this hole down along the inside wall of the cabinet out of sight. It then goes back into to the exterior wall through a 3/4" hole at the bottom of the cabinet. I temporarily removed the AC outlet which is under the cabinet to provide another place to continue fishing wire."

    Referring to that 3/4" hole: does this hole go through the outside wall of the trailer, then requiring another hole just above the driver's side pass-through door? Or are you able to take the wire through the cabinet wall and into the pass-through compartment while staying inside the trailer's outer wall?

    1. Thanks for comments. Wire stays within the wall space, between studs. Your manufacturer may be able to provide you with stud locations.


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