Solar Trailer

A while back, I saw a number of commercially-built solar trailers going up for auction. They looked great, but were also EXPENSIVE! I had a number of parts around, and wondered if I could build something similar for a whole lot less money!

Here’s my take on an inexpensive DIY Solar Trailer!

To start with, I had 6 used 250 watt solar panels and an old utility trailer. Those would be the heart of the project. Beyond that, I would need some metal and a way to mount the panels to the trailer in such a way that they could rotate. For any NEW materials for the project, I wanted to use easily accessible “off-the-shelf” parts.

Three solar panels in a row is just shy of ten feet long. That’s a standard length for certain building materials, including black gas pipe. I purchased one piece of 1.25″ gas pipe from the big box store and a number of 1.5″ exhaust clamps. The panels would mount to the pipe with the exhaust clamps, and then the entire assembly would rotate on bearings on either end. It could rotate vertical for transporting the trailer, or out to an appropriate angle for soaking up the sun.

Here’s my first test of rotating the panels

So much of the physical work on the trailer was just measuring, cutting, and welding of metal. There was also plenty of drilling holes! More than anything, it was really just an assembly project. Here’s an overview of the steps to get done the basics of the trailer.

Before going any further on the project, I really wanted to make sure that it was road-worthy. None of my work on this would matter if I couldn’t safely and legally transport it on public roads. I took the trailer out for a spin to see how it would tow. I wanted to make sure that there weren’t any issues with vibration, wind, or other unexpected problems. While I was out, I took it a local landscaping company to use their drive-on scale. At this point, the trailer was in the neighborhood of 1,000lbs. That’s good, as I still needed to add the other three solar panels, a battery, and other equipment!

One thing that I wasn’t completely happy with was the mechanism for locking the solar panel rotation at a certain angle. In the first spot I did this on the trailer, it was just a last minute thing to lock the panels down. With a little more thought, it could certainly be improved.

Next, I needed some sort of an enclosure to house and protect the battery and electronics. I really wanted something appropriate and weatherproof, but more than anything, I wanted something CHEAP! The enclosure would need to be either a durable and nonconductive material like plastic OR some sort of metal which would be grounded. In the end, what seemed to best fit the bill was an aluminum pickup truck bed toolbox. There are many of them available, they are designed to be weatherproof, and they are usually made from aluminum, which is light and durable.

I hunted through Craigslist and Facebook Marketplace and found a full-size box for sale for $50. The only downsides were that there were no keys, and I later found out the gas lifts on it were shot. Amazingly, the entire box fit inside our Chevy Volt WITH the hatch completely closed! (#FitsinaVolt)

I really liked the look of the truck box cross-wise in the trailer. Unfortunately, I had already welded down the location of the solar panels, and they would have hit on the box. Also, adding the battery and everything else to the FRONT of the trailer would have made the tongue heavier than appropriate for towing. Instead, I ran the box the length of the trailer. The size of the box was PERFECT for the solar panels to exactly miss while rotating into any position. After the lid of the box kept flopping down on me a few times, I spent $10 for new gas shocks and installed them to hold up the lid.

Inside the truck bed toolbox, I installed the battery, inverter, and other important parts. We’ll come back later with more details on that.

The second wing of solar was built the same as the first, except that this time I used 2 inch pipe instead of 1.25 inch pipe. The first wing looked like it had a little bit of a sag in it when rotated flat. I figured that a larger diameter pipe would improve stiffness.

I also improved the rotation lock mechanism a little more by simply drilling a hole through the 3″ c-channel upright for the pin to go through instead of welding on the 3/4″ square tube.

Next, I repainted the trailer frame and reinstalled the wood planking.

The Maiden Voyage of the trailer would be out to a Sustainability Fair at the local Nature Center. I was still working on the trailer the evening before, and wished I would have had a little more time, but everything was together, produced power, and was road-worthy for the event.

I towed the trailer to the event with no issues at all. After setting up, I spent the day talking to the crowd and demonstrating how the solar could produce power. It was VERY hot and humid, and I’m glad I brought an electric pedestal fan as a sample device to power! I also charged the Chevy Volt (at 8A/120V) for a few hours. When I arrived, I had 1 electric mile left, and when I was ready to get, the meter said 11. Gaining 10 miles of range while just in a parking lot isn’t bad!

Here’s a playlist of all the videos I’ve shot about the project:

I plan to continue to improve the solar trailer and take it out to as many events as I can in the future.