DIY Portable Solar Panel Generator Trailer

Check out the Step by Step YouTube video we did for this project here.

In this project we build a Solar Generator or in other words a portable bank of batteries and solar panels to provide us with 115 volts of power anywhere (like you have in your home) on our property!

We used the following supplies to build this. We used scrap lumber and wires from our homestead and an old garden tractor and we purchased the panels, inverter and batteries on Amazon (links below).

The items below can be customized for example if you want more power you could purchase a larger inverter. If you want longer lasting batteries you could buy higher amp hour batteries, etc:

1. Garden Trailer
2. 2x6 lumber, 5/8 plywood for cover, 2x4 lumber for mounting

3. Solar Panels: https://amzn.to/2NG7RD7

4. Solar Y Branch Connectors: https://amzn.to/2O1sZCB

5. Solar Extension Cables: https://amzn.to/2O2pgVl

6. Solar Panel Mounting Z Brackets: https://amzn.to/2qI917U

7. Batteries: (These are not the batteries I used-- these are big 100AH batteries. The batteries I used were 40AH smaller but I couldn't find those on amazon. I had them left over from an electric scooter. The link below are more expensive and larger- but they worked great on our tiny house project. https://amzn.to/34RZ3Q9

8. Solar Charge Controller: https://amzn.to/32IvQ92

9. Battery Cables (4): https://amzn.to/2Cvk47f

10. Power Inverter: https://amzn.to/34WWfBv

11. Weatherproof outlet cover
12. 15 amp outlet
13. 15 amp cord end
14. 12 gauge romex wiring
15. 12 volt LED light (https://amzn.to/32FuNXc this is similar to what we used)
16. FlexSeal:https://amzn.to/36Ulvdq
17. Construction Screws 1 to 2 inches
18. Spray Paint
19. 2 Inch Foam Board Insulation

The goal of this step is to build an enclosure to house the batteries and inverter and electrical components.

For this step you have multiple options. We are not skilled in welding and metal work or we would have used metal to enclose our batteries and inverter. Instead we used lumber. Ideally pressure treated lumber and plywood should be used- we did not use all pressure treated lumber (but in a later step we use some FlexSeal to waterproof these parts).

Using 2x6 lumber we built a frame around the metal walls of our garden trailer. We did this to make it stronger (the trailer walls are light duty) and to have something substantial to mount the battery cover and panels to. We used construction screws and mounted the 2x6s directly to the metal walls of the trailer and we connected them to each other, essentially forming a large box.

Next we used a piece of plywood and two hinges as a cover. This hinged cover will provide access to the batteries within.

Next we flipped the panels over to access the back of them. We used 6 solar panel Z mounting brackets on the back of the 2 panels. We then attached these brackets to 2x4 lumber spanning across both panels. The goal here was to make 2 panels into one solid piece. Using additional lumber we connected the cross span to each other, essentially creating a large frame which the panels are mounted on.

We then add the second set of hinges to this frame and mount these hinges to the existing hinged battery cover. This creates 2 hinged components - #1 the battery cover and #2 the solar panels.

Now that the panels can be hinged up or down to any angle, we need a bracket to support the panels at a specific angle. You can google Solar Panel Angle Calculator to find a specific angle based on your geo location and the time of year. For simplicity we used about a 45 degree angle.

We positioned the panels at about 45 degrees and then cut some 2x4 lumber to height. Using some smaller hinges we attached the two 2x4s to the panel frame. We also added across beam so that both 2x4s move together.

With this in place we can lay the panels flat on the trailer for transport and then hinge them up to 45 degrees to collect the maximum amount of sun rays while charging.

Next we cut some 2 inch pink foam insulation to size for the bottom of the battery box, the sides of the battery box and a top cover (not pictured).

We have freezing cold Wisconsin winters here and the goal of the insulation is to try to keep the batteries as warm as possible. We also plan to store the trailer in our heated garage when not in use.

We are using a 12 volt system and wiring the batteries in parallel. This means each positive is wired to the other positive terminals and all negatives are wired together creating one large 12 volt battery. Some systems are 48 volts in that case you could wire in series, positive to negative to positive to negative etc and that would turn the system into a 48 volt battery bank as an example. But for our project we are using a 12 volts battery bank.

The system is comprised of four main components:

1. The battery bank

2. The solar panels

3. The solar charge controller

4. The 1600 watt inverter

The battery bank feeds into the inverter. The inverter converts the 12 volts into 115 volts. Everything else is central to the solar charge controller. As seen in the wiring sequence image, the battery bank wires (positive and negative) get connected to the two center screws of the solar charge controller. The controller is neatly labeled. It's important to connect the batteries first and the panels second.

Next the solar panel wires (positive and negative) get connected to the first two screw terminals on the charge controller. In our case we also purchased some Y Branch Connectors: which uses water proof connectors and combines each set of wires from each panel down to one positive and one negative wire which feeds into the charge controller.

Optionally, the charge controller also has a 3rd "load" set of screws. This is to power any 12 volt devices. There is a push button on the controller on/off for any load applied here. In our case we used this to power a 12 volt LED light on the outside of our trailer. We plan to use this to provide light for any night projects. Unlike the 115 volts from the inverter, this power comes directly from the battery bank by way of the charge controller.

With everything wired the charge controller LED screen turns on. We can see the current charge of the batteries and we can toggle on and off settings. We left the default settings. One main function of the charge controller is to ensure that the batteries are not over charged. By default when the batteries reach a full charge, the controller disables power to the batteries to protect them from overcharging.

We also powered on the inverter and plugged in a 115 volt standard house hold lamp as a test, it fired right up and worked great!.

Next we used some Flex Seal to seal up all of the lumber and help ensure a long lasting, weather tight seal. We also spray painted the wheel hubs and the entire trailer to make it look nicer.

With the paint dry, we added an LED light and external outlet. While we could lift the battery conver and connect an extension cord directly to the power inverter, we wanted a more convenient access point, so we mounted an external water proof outlet to the outside of the trailer. We wire a plug to the inside of this and plugged it into the inverter. Now we can plugin into the trailer without opening the battery cover.

We also added a 12 volt LED light wired to the LOAD screws of the charge controller. With this in places we have a nice light to brighten up any night time projects.

My wife Jen loves her Cricut machine and has made some pretty impressive vinyl stickers and signs, so we made a few for our solar trailer! If you want to learn more about Cricut Signs check out Jen's YouTube channel.

We made one sign for the name of our homestead and affixed it to the rear of the trailer. And we made a cool power/voltage icon sign for each side of the trailer.

As a final step we tested the solar trailer over the course of 2 weeks. We powered up our wall tent and later our dog kennel for several days.

Our dog kennel has a 115 volt ceiling fan and four 115 volt lights as well as a radio and large exhaust fan. The solar trailer had no problem powering all of this. After some regular use and some decent sun, after 3 days we the batteries increased 1/2 volt! Not only did we power everything we needed we also gained some voltage!

Check out the Step by Step YouTube video we did for this project here.