RV Solar Wiring

Once the rack was finished and the panels installed I had to figure out the wiring from the roof to the equipment inside. One benefit of the Solarland panels is that they use thicker wire. They come with the MC4 solar connectors so I ordered #8 wire to attach to the solar controller. I had planned to use a combiner box on the roof to bring one wire down to the controller but I found Y connectors and wire that I used instead.

8 AWG wire with MC4 connectors
8 AWG wire with MC4 connectors
Panels wired with connectors
Panels wired with connectors

I had two panels instead of three but these connectors functioned the same as a combiner box allowing each panel to connect directly to the breaker box in parallel. Parallel connections double the wattage of the two panels, while connecting them to each other and then to the breaker box would double the voltage. The controller could accept either but I decided on parallel connections to increase the delivered wattage to 360 watts.
The common method for bringing the wires down into the RV is to snake them through the refrigerator vent. In order to get the vent lid to fit after I drilled a hole in the underlying screening I had to chop off what was the front and turn the cover around to have the cut off side face the rear. I patched the opening in the screen with eternabond tape. I ended up with the wires in the refrigerator vent compartment. They were not difficult to snake through the vent.

Wires in refrigerator vent cabinet
Wires in refrigerator vent cabinet

Once there I had to figure out how to get them to the rear compartment where I planned to install the equipment. The problem with drilling into the floor is that the fresh water tank is directly under the refrigerator. Luckily there was about an inch space between the tank and the wall.

Refrigerator vent compartment floor
Refrigerator vent compartment floor

I used a back scratcher to pull the wires into the compartment since my fingers didn’t fit.

Fishing wires from behind the water tank
Fishing wires from behind the water tank

But I had another issue with the breaker box. The small box is designed for two wires to be pulled into the box through one opening on each side. But I had increased the size of the battery wire to 2AWG. So I had to use a reducer to connect to the breaker and that took up the entire hole. My solution was to drill extra holes in the box. I drilled these on the side through the cover as I didn’t think there was enough room on the top and bottom. The breaker box was very full.

Fitting wires in breaker box
Fitting wires in breaker box
Victron Solar controller and Midnight solar baby box
Victron Solar controller and Midnight solar baby box

The #2 wire was also too thick for the controller so I used some jumper wires with shrink wrapped butt connectors. The breaker box wiring was time consuming. And the equipment was installed in a small space.

Equipment install in great water tank cabinet
Equipment install in fresh water tank cabinet

To connect the wires to the batteries, I had to snake the wire past the front of the water tank to the floor under the refrigerator where I drilled another hole to accommodate the black and red wires. These joined the others in the battery compartment. I used thicker wire because of the distance between the controller and the batteries. Normally #4 wire is used to connect the controller to the batteries but the DC current drop over the distance is less using thicker wire

Wires to and from the solar controller
Wires to and from the solar controller

The wiring of the breaker box and solar controller to the batteries was relatively straightforward. I just had to reason out the diagram. I had a 15 amp and 40 amp breaker. The 15 amp went on the panel side since my panels are rated at about 5 amps each. The 40 is on the 30 amp solar controller side. Northern Arizona Sun and Wind recommended these two breaker sizes for the smaller RV system.

Solar controller and breaker box wiring
Solar controller and breaker box wiring

Our first time camping with solar was in a lovely federal campground at Shadow Mountain Lake near Granby, Colorado. What a luxury to have power to charge the batteries without using the generator.

RV using solar panels wit no hookups
RV using solar panels with no hookups
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