Installing the system is fairly straightforward for anyone familiar with rudimentary electrical and mechanical work, and instructions are provided with new charge controllers or are easily found online by those venturing into this for the first time. See below for wiring diagrams. I will point out some common pitfalls with RV Solar installations so you can avoid those. And I’ll talk a little about how to monitor your system’s performance once it’s operational.
How to Connect the System
Below are two diagrams showing the wiring runs for typical RV solar systems. Both diagrams show panels wired in parallel in a nominal 12v system (meaning each panel’s voltage is no higher than 21v or so). As mentioned earlier, higher voltage panels may be wired in the same manner as long as a charge controller is used that is capable of reducing the voltage back down to nominal 12v for output to the batteries. If you are wiring in more panels than that shown in the diagram wire them into the junction box the same as those shown. The first diagram shows 12v batteries wired in parallel. The second diagram shows 6v batteries wired in series.
Above: RV Solar System with 12v Nominal Panels Wired in Parallel and 12v Batteries Wired in Parallel
Below: RV Solar System with 12v Nominal Panels Wired in Parallel and 6v Batteries Wired in Series
Rules of Thumb:
- Mount panels where they will not be shaded, not even partially shaded, by such things as a/c units, roof vents, rooftop satellite systems or antennas, etc. Raise your vent lids and any other movable objects on the roof and consider how their shadows will travel across the roof before deciding where and how to mount your panels. Even a partially shaded solar panel can have drastically reduced output.
- Mount your charge controller as close to the battery bank as possible without it being in the same compartment as the batteries, especially if that compartment is sealed. You want that wire run to be as short as possible to minimize voltage drop. But batteries produce explosive and corrosive gas that can explode if there is a spark, and the corrosive nature of the gas can damage the controller over time. So don’t mount the controller in the battery compartment.
- Before wiring your system together, cover your solar panels so they are not producing electricity. This will prevent inadvertently shorting your system out and possibly damaging components.
- Read the instructions that come with your charge controller. I can’t speak for all, but the instructions that came with my Morningstar controller were great. It’s one of the few instruction manuals I’ve kept after installation was complete, and I often refer back to it for information regarding my system.
- Strongly consider buying a permanent meter to attach to your system for system monitoring purposes.
Regarding the last item, some charge controllers come with their own meters installed. Some offer that as an optional item at additional expense. Some are better than others, some more functional than others. As I mentioned in RV Solar Part 2, I have a separate meter on my system, a Trimetric 2020, predecessor to the 2025. This allows me to see how many amps are going into the system, what the current battery voltage is, how many amps I’ve used since the last full charge, etc., and allows me to see how much power individual appliances use. It’s a great little device. Without it, I’d just be guessing how well the system was performing. My charge controller has three LED lights that give me some information, but it is very limited. There is an optional meter offered with that charge controller, but I opted for the Trimetric instead, so can’t really comment on the other’s functionality.
Thanks for Reading
Thanks for reading my blatherings on RV Solar. It’s something I knew little about before deciding to build my own system. The process of learning about solar and eventually putting together my own system was something I found very enjoyable. And I especially love being able to camp out in the middle of nowhere without a care in the world with regard to electricity usage.
And as I said in the beginning, I’m certainly no expert, but I do have enough experience to pretend to be one in an online blog.
Below are links mentioned throughout this series that you may find helpful in gathering more information on this subject. Good luck with your system.
Handy Bob Solar
U.S. Solar Insolation Map
The 12-volt Side of Life, Part I
The 12-volt Side of Life, Part II
Northern Arizona Wind & Sun’s Battery Information Page
The Battery Council International’s Lead Acid Battery Page
Trojan’s advice on flooded lead-acid battery maintenance
Physical Battery Size by Group Number from batterystuff.com
Voltage Drop Calculator
20-foot, 4 gauge Jumper Cables
To Fuse or Not to Fuse?
Morningstar’s Pulse Width Modification (PWM) Document
Blue Sky Energy’s Explanation of How MPPT Works
How to connect your batteries correctly and efficiently