Expanding the solar setup on our truck camper

We had been thinking about adding an additional solar panel to the truck camper for a couple of years and finally got around to doing it.  We already had a 150 watt panel installed by the dealer (Truck Camper Warehouse) and an existing solar charge controller which came with the camper from Northwood.  

Zamp ZS-30A controller

We wanted to confirm that anything we purchased would be compatible with our existing setup, so we reached out to the folks at Zamp Solar.  Joe from Zamp Technical Support group was very helpful in both confirming which panel we already had (from a picture we sent) and in figuring out exactly which panel and parts we would need for the new install.  He was very responsive both via phone and email throughout the process.  

We also sent an email to the folks at Northwood to confirm what gauge they use for the solar wiring as we wanted to make sure it would be heavy enough to handle an additional panel.  10 gauge was the answer.

Our existing controller can handle up to 30 amps or 480 watts, so we probably had enough capacity to add two new panels, but decided to go with just one as we like having space to walk around on the roof for maintenance.  In addition, the existing 150 watt panel did pretty well charging our 2 AGM batteries most of the time so doubling our capacity should be sufficient for our needs.  

Zamp has a great system that uses a multi-port roof cap that makes adding additional panels very easy.  Unfortunately when our original panel was installed it was hard wired, so in addition to getting the new panel, we also needed to install a roof cap and add a plug to the wiring on the old solar panel.  Zamp sells through an authorized dealer, Specialized Products.  Here are the parts we ended up needing:

170-watt Expansion Kit (KIT1009)
10' UV Rated Fused SAE Solar Panel Wire 12-2 (WIR1016)
2 Port Roof Cap, Low Profile UV Resistant (ZS-2B-CAP)

The original panel had been installed over the spot where the wires came out of the roof.  that meant that we had to remove the old solar panel and pull the existing cap in order to install the new port.  Removing the old panel was easy, but getting the old cap off without damaging the rubber roof took a bit of care.  Some gentle prying with a putty knife did the trick.  

We removed some of the excess sealant under the old cap gently with the putty knife.

After pulling the wires, we found that they were damaged, either by the folks at Northwood who originally wired the camper or by the installer.  We weren't particularly happy about it, but I guess we were lucky it had never caused an in issue.  Since the damage was close to where I needed to cut the wires the damage would be consumed by the splice.

We reattached the part of the wire that passed through the bulkhead seal by bell twisting and soldering, then used adhesive filled shrink wrap tubing from NAPA to seal them. That gave us plenty of wire to work with and the damaged insulation in the red wire was covered.  Next step was to install the new Two Port Roof Cap. The wire ends were tinned in preparation for that.  The OSB and cardboard you see in the pictures are just there to protect the roof from any dropped solder or tools.  

It was a tight fit, but we were able to feed the connections back into the roof. We applied a tiny amount of dialectric grease to all four ends and tightened up the connectors for a long term connection.  We decided to mount the port so the connection side were facing the back of the camper, and therefore out of the wind and rain when we are driving.  The downside is that this makes it harder to access if we need to plug/unplug one of the panels.  We put Dicor under the port, screwed it down, and then sealed around the outside with more Dicor.  

Once the port was installed, we needed to add the new cable (10' UV Rated Fused SAE Solar Panel Wire 12-2 (WIR1016)) to the old panel to allow it to plug into the new port.  The bare post on the port was negative.  We used a VOM to test connectivity on the new cable, from the connector to the other end, so we would know which wire was negative and which was positive when connecting it to the old panel.  The new wires were attached by bell twists and soldering and then sealing with two layers of adhesive wrapped shrink tubing.  We included an extra layer on the WIR1016 cable as it was a smaller gauge and we wanted to make sure it had a perfect seal. They make connectors that let you do this without soldering, but we felt that solder and shrink wrap tubing would result in a better long term connection.

Now that the wiring was complete and the port installed, it was time to re-install the old panel.  The new port was taller than the original cap and did not clear the old panel with the existing brackets.  In order to address that, we added aluminum square tubing to the underside of the old panel and then attached that to the brackets.  It was difficult to align the multiple layers and get the bolts in place while working on the roof, so we used JB weld to attach the square tubing to the panel and to hold the bolts in place.  Once they were all epoxied together, it was much easier to set the panel on top of the brackets and add the nuts to bolt it in place.  We did need to get longer stainless steel bolts as the originals were not long enough to go through the panel, aluminum tubing and the brackets.

With the new cable, there was quite a bit of excess wire which we did not want whipping around, so we drilled a hole in the side of the panel frame that we could thread a wire tie through to hold it in place. We could now put the old panel back in place and attach the nuts using Lock-Tite and nuts.

The last step was to attach the new panel to the roof.  It was very straight forward.  We put Dicor under the brackets, screwed the brackets into the roof and then sealed around the brackets with another layer of Dicor. More Dicor was used to keep the wire running to the port in place.

The completed project! 
Old panel is on the left, new on the right.  We used Dicor to attach the wire that runs from the new panel to the roof so it won't blow around when we are driving.