RV Solar 101 – Part 9, Installation and Monitoring

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.

12v Batteries, Everything Wired in Parallel
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
12v Panels in Parallel with 6v Batteries 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
Sun Electronics
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



  1. doug w says:

    Hello ChromolyWally,

    I must tell you how much I enjoyed your article on solar. I have been researching this topic since last winter and like you, have learned a bunch. For me, the research is a very enjoyable pastime and it was interesting to see the number of opinions and theories once you have weeded out all the chafe. It took me about 3 times through handybob’s blog (yikes!), living the 12V life, etc to start to “get it” but I have learned more about batteries and charging than I ever realized was possible. This made all the “kits” seem like a waste of time (and a lot less fun!) for a self-proclaimed do-it-yourselfer. Your article is so well presented and I especially like the way you explained all the inefficiencies and design considerations. Very simple, accurate and straightforward. Can I assume you opted for the Tristar (say over the Prostar) for the ability to control set point voltage? I have started sourcing gear and the only questions I am left dealing with are minor items like wire lug types and fuse/breaker choices. Once again, excellent write up – I only wish I had found this near the beginning of my research cycle.


    • gibsito says:

      Hi Doug – glad you enjoyed the write-up. I sense that you are as enthusiastic about this as I am. It definitely is a fun project and something that continues to hold my interest years after the initial research. As far as my choice of controller, yes, the ability to control set point was a requirement for me. The 45-amp Tristar is definitely overkill for my relatively small system though. Sometimes I think I should have gone smaller with the controller. It’s not likely I will ever add more panels since what I have now meets my needs quite well. Oh well, it’s an excellent product and I certainly don’t regret buying it for that reason. Regarding Handybob’s blog, I think I went through it that many times as well. There’s great information there – but you have to dig for it. Enjoy putting your system together and watching all that “free” electricity flow to your batteries. I never get tired of watching that. :)

      Best of luck,

  2. Gil Schwab says:

    Thks for the info…I am installing a small system to keep my battery charged for min use with 55 watt solar panel, mppt charger, and 12 v deep cycle battery and 400 watt inverter. I am flying into Mexico and have to keep my check in baggage to minimum…question, will i need fuses and disconnects for panel, inverter and battery for such a small system??…I am installing voltmeters for both panel and battery..using # 10 wire…
    Thks Gil

  3. gibsito says:

    Hi Gil – I don’t think you’ll really need a fuse on the panel circuit since you just have a single panel, but a kill switch on the panel circuit and another on the battery circuit is a good idea as well as a fuse on the battery side of the charge controller. As far as the inverter – most of those are already fused as far as I know. The #10 wire should be fine for a 55 watt system, unless you’re talking about a half mile of it. :-)

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