Introduction
Harnessing the power of the sun is the most popular way boondockers recharge their RV batteries. Because the sun is free, it’s common for boondockers expand their battery banks to 2, 4, or even 8 batteries. This tutorial will explain the process, in layman’s terms, of adding solar panels to your RV, how to connect them together, wire them into a solar charge controller and battery monitor, and then wire them into the battery bank.
How Many Solar Panels Should I Buy?
It depends on how many batteries are in your RV…
- If you have a single 12 volt battery, we recommend getting 300 watts of solar panels ( 3 x 100 watt panels, or 2 x 150 watt panels, etc.)
- If you have two 12 volt batteries, or two 6 volt batteries, we recommend getting 600 watts of solar panels
- If you want four 12 volt batteries, or four 6 volt batteries, we recommend getting 1,200 watts of solar panels.
Note: these are minimum suggestions, you are free and encouraged to add more solar panels if you believe your electrical needs will be greater.
Should I Install More Batteries at the Same Time I Install Solar Panels?
You don’t have to. It may be easier to add solar panels first, then later expand your battery bank. Your solar charge controller, which we’ll be installing during this process, will protect your batteries from being overcharged by too many panels.
Should I Buy Rigid Solar Panels or Flexible Panels?
Most boondockers buy rigid, glass solar panels. These panels tend to last longer because they remain elevated above the roof by about an half-inch, just enough to let cool air to pass below. Meanwhile, flexible panels are usually sit right on the roof itself, and will get very hot and thereby degrade the solar cells in the panel. Moreover, flexible panels tend to get dirtier because the panel tends to form small pools of water after a rain which evaporate and leave behind mineral deposits. Rigid glass panels tend to remain flat and minimize water pooling.
Flexible panels are more advantageous for RVs with curved roofs, such as tear drop trailers. Flexible panels also withstand falling objects, though it’s rare to have objects falling on your RV roof.
What Solar Panels Should I Buy?
I recommend getting rigid, glass, 18 volt solar panels, rated for 100 watts up to 150 watts. The panels themselves will come with mounting brackets designed to fix to your RV’s roof, and may or may not come with mounting hardware. Here are three brands I recommend off of Amazon…
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You will also need to buy wire and connectors to connect these panels to each other, and utlimately into the solar charge controller.
- Get 10 gauge wire in both red and black (for positive and negative)
- Get at least four feet of wire for each panel
- Get an additional twelve feet of wire to run down into the solar charge controller.
- Get Dicor caulking (for the screw holes)
- Get Eterna bond tape (to tape wires down to the roof)
What is a Solar Charge Controller?
A solar charge controller is a battery controller that is designed to be used with solar panels. It makes sure that your batteries do not get overcharged, and it also makes sure your batteries do not lose their power when the sun disappears at night. A good solar charge controller will monitor the state of charge in your batteries and feed more power to them when they’re low, and curtail power when they reach full charge.
My recommended solar charge controllers (linked to Amazon.com)
- Victron (the best, but most expensive)
- Sea Blue
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What Is a Battery Monitor?
A battery monitor is a small device that monitors a battery’s state of charge.
Mounting the Panels to the Roof
- You are going to need to get up on the roof, and try to locate where the crossbeams are. You want to mount the panels as securely as possible because when you drive your RV at up to 70 MPH, those panels can get sucked up into the wind if they’re not well secured.
- You will need to know if those crossbeams are made of wood or aluminum. Use either wood screws or sheet metal screws.
- Make sure to use heavy screws long enough to reach through the roof and into the crossbeams.
- Once you have the panels mounted securely, spread Dicor caulking around the screw holes to seal them off from water.
Wiring the Panels Together
Mounting the Solar Charge Controller and Battery Monitor
The best place to mount your solar charge controller and battery monitor is within 12-24 inches from your battery bank. Find a wall or support beam, and mount them there.
Wiring Your Solar Panels to the Solar Charge Controller
Wiring Your Solar Panels to the Batteries
Wiring Your Batteries to the Battery Monitor