I wanted a way to keep my battery happy when the trailer was in storage for a while. With a few 24/7 draws (very small amperage) on the battery between a monitoring system and a TPMS booster (I will rewire this to switched power in a later project), there was a very slight drain on the batteries.

The build out was very easy. I wanted a frame that was set to the ideal angle to capture the sun for where we live. I also wanted to ensure that it didn’t go flying away. Lately, we’ve been getting 30-40mph wind gusts, so I wanted to anchor it well.

I built a frame out of some scrap metal I had laying around from another project. When I built the frame I made a little “tray” for 2 bricks that we had left over from a backyard project. Between the weight of the frame and the bricks, this sucker isn’t going anywhere. I didn’t do much for security on the panel, as I’m not worried about theft where it is stored. If that changes in the future, I’ll weld a D-Ring to the frame and chain it to the frame of the trailer.

I used the Z-Amp port on the side of the trailer (which was directly connected to the trailer, bypassing the solar controller already installed in the RV for the roof-top solar.

Below are the items that I used in the build:

Renogy 100 Watt 12v Monocrystalline Solar Panel

Renogy “New Edition” Voyager 20a PWM Waterproof Solar Charge Controller

Renogy Adjustable Solar Panel Tilt Mount

ZAmp adapter to MC4 with a 10′ Cord $35 from OffThe GridRVs

I initially used a different charge controller that was about half the price. I learned a valuable lesson the hard way with that one. The controller was sending over 15v to my batteries for who knows how long while it was in storage. Thankfully, the batteries were isolated and didn’t fry any of my equipment with the over-voltage. When I realized what was going on, both batteries were toast. I now have a monitoring system installed that alerts me to over voltage; you want about a maximum of 14.4v going to lead acid batteries. So far, this controller hasn’t gone over 14.4.

The install was very straight forward. I cut the Z-Amp connectors off the cord about 18″ from the end and wired them to the solar-in on the controller. I then connected the remaining 8.5′ of cord to the “battery out” portion of the controller. The long end of the cord plugs into the Z-Amp port on the side of my trailer and the MC4 connectors plug directly into the solar panel with no extra fuss. The entire system is waterproof (including the controller!).

I’ve run it this way for several months now (the controller failure was discovered around January 2021), and my batteries have been very happy. As things warm up out here and the path of the sun changes in the sky, I’m getting more and more charge into my batteries. With our trailer in covered storage, the roof top solar panels weren’t able to do their job. This has been a good solution for that, and when we go boon docking in the winter we’ll have plenty of power without needing to run the generators.

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