If you would like to build a 8.64 kWh Solar Panel Rover, then this is the instructable for you! Operating descriptions will also be included in this instructable as well as brief assemblage directions. Originally this solar panel rover was made to bring electricity to Pomona College's Organic Farm which did not have access to the grid. Now the rover is used to power a large variety of outdoor events on the campus.
The rover features three solar panels, for a total of 570 W (each panel is 190 W), that are wired in parallel that are connected to a power controller that then charges six interstate batteries. The batteries are wired in parallel and are wired to a 1000W, 12V inverter with two electrical outlets. Between the batteries and the inverter is a fuse.
This Solar Panel Rover includes:
NOTE: If any part of this instructable is incomplete or you have suggestions please provide comments!
Step 1: Mounting the Solar Panels
You want to make sure that you purchase the panels and the trailer together because the panels are the largest component of the solar rover and it is imperative that the panels fit on the trailer.
In order to decide what angle you would like to fixate your panels, the following website provides suggestions depending on your location in the world. It mostly depends on your latitude:
The panels were purchased as a module and were screwed onto a metal frame and then wired in parallel to have 200 W optimum (24 V*8A) per panel. Between the charge controller and the panels is a disconnect that has a switch accessible for turning the rover on and off.
This disconnect is flipped "on" (connected) second when the rover system is turned on, and first when the rover system is being shut down. This is to prevent any potential overloading in the system.
Step 2: Charge Controller
The Outback systems generally come with a pretty detailed manual installation, in this solar panel rover the charge controller was mounted to apiece of ply wood and wiring connections followed a manual that can be accessed here:
The mounting on plywood directions start on page 12 and are specific for mounting photovoltaic arrays. It will tell you exactly where to mount the positive and negative wires of the battery and solar panel. Be sure to do this on a cloudy day or with the solar panels covered up so that you are not at risk of electrocution when performing the installation.
The above pictures show the charging status of the charge controller.
TROUBLESHOOT: Be sure to check the resistance between all the wires to ensure that they are connected and functioning. Especially when the solar rover has spent a considerable amount of time in the outdoors corrosion can begin to occur at exposed areas and the charge controller will show a presence of voltage but not enough current to charge the interstate batteries.
Step 3: Interstate Batteries
Six interstate batteries are mounted behind the solar panels and within the triangular space that the metal frame creates. They are connected in series with car battery cables that have soldered gauges at either end. The cables at the end of the batteries is then threaded through the back of the ply wood panel and connected to the charge controller. These cables can also corrode over time so ensure that there is complete coverage of metal wires and that connections are tight. An ohmmeter can be used to check the resistance of the wires.
In this particular set up there are six interstate batteries, each is 12V and 120A such that they have the capacity of 8.64 kWh. They are wired in parallel. If the batteries were completely dead the 200W panel (this system has 3) would take 15 hours to charge the batteries at full capacity.
There is a DC disconnect between the battery and inverter that is turned on first (connected) when the solar rover system is turned on and turned off (disconnected) second when the solar rover is turned off.
Step 4: Inverter
This system has a 1000 W inverter, although it could probably have a larger inverter. It has two 120V outlets that any device can be connected to, make sure you don't go over the 1000W because then the fuse could blow in the inverter.
Also in order to prevent damage to the inverter on the battery side a Go Power inverter/battery fuse was purchased. Its installation is pretty straightforward as all the electricity is wired through battery cables.
Step 5: Theft Proofing the Rover
The Solar Rover has several expensive components and sometimes will be used for evening events that extend past the bedtime of the solar rover keeper. Therefore tamper proof screws and bike chains can be used to fortify the solar panels and the trailer. Unfortunately a way other than the strapping down of the batteries has not been created (will be trying to install square tubing over the batteries in place of strap).
McMaster Carr Tamper Proof: