Solar Power Charge Controller Safety

Hi All,

I have had a small PV system for my camper for about 2 years now. The panel is a Kyocera 125W, with wiring connecting it, via Anderson connectors to wires secured by screws to the input terminals, + and -, of a charge controller, then wires secured by screws to the output terminals, + and -, to connectors that I would secure to the + and - terminals of my batteries. I have 2 Trojan T105 batteries, 6v each, connected in series to make 12v. The charge controller was manufactured by the outfit here in Scottsdale where I bought the panel from.

This system has worked fine for my camping for the last 2 years, and I've been quite happy with it.

However, this past weekend, I was out camping with my wife and dogs in a remote part of Arizona, and I did what I usually do. When I first get there, I bring out the solar panel, which is connected together with wires and all to the charge controller, and connect the output wires from the charge controller to my battery terminals. I then went inside the camper and turned on the power disconnect switch to my camper. As soon as I did this, I noticed a loud feedback noise coming out of my camper's stereo speakers. After a couple of minutes of looking for the cause, I went back outside, and noticed a burning smell. When I looked down, I saw that my charge controller was shooting out a jet of sparks! As quickly as possible, I first disconnected the solar panel from the charge controller via the Anderson connectors, which are sort of like quick connect connectors. I then popped off the top of my battery box, and disconnected the wires from my batteries that were coming in from the charge controller. That stopped everything, ie., the sparks, etc., but my charge controller had partially melted.

The charge controller was rated for 22 Amps, I think. I also noticed, when I first hooked up to the batteries, that since they were already full from the trip up, the Battery Capacity Meter was already showing FLOAT, just prior to all this occuring.

Needless to say, although I was fortunate nothing actually happened, ie., my batteries and solar panel itself were undamaged and we continued the camping trip overnight on battery power, I was also scared of what could have happened, ie., my camper becoming a death trap for us and our dogs. I was very lucky that I just happened to step out and be able to address the situation when it first started occuring. MY MAIN CONCERN is to take steps that this type of thing won't happen again. I never thought about something like this happening before.

To that end, I have a couple of questions.

1.) Does this sound like something where the charge controller itself failed? It was not a brand name charge controller. It was one they custom made themselves. I KNOW I didn't hook things up backwards, ie., positive wire to negative terminal, etc., as I leave the whole thing connected together except for connecting to the batteries. I simply connect or disconnect the wires coming out of the charge controller, which are color coded, to the battery terminals.
2.) Could anything else have contributed to this? For example, this system is not permanently affixed to my camper. I have a long string of wire, part of it going from the solar panel to the charge controller, and part of it going from the charge controller to my batteries. I string this out when I set up camp, enabling me, in the summer, to park my camper in the shade, then string out the solar panel so it is lying in the sun. When I'm done, I simpy disconnect from the batteries, wind up all the wire, and put the solar panel, charge controller, wires and all, back inside my camper for stowage. I was wondering if the winding and unwinding of the wire, over the last couple of years, might have led to any part of the wires becoming severed to the point of causing an electric arc. Although if that happened, I don't know why I had enough power to light up the Battery Capacity Meter properly.
3.) I am looking to prevent this situation from recurring in the future, by buying a BRAND NAME controller, such as the Outback MX 60. This might be overkill, as it appears that the MX 60 is rated for far more than the amperage put out by my panel, but wanted to have that extra buffer of safety, even if I have to pay quite a bit more for it. Would this be a good idea?
4.) Any other suggestions for safety?

My main concern is safety, and to not have this situation occur again.

Many thanks in advance for any advice!

Best Regards,



  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Solar Power Charge Controller Safety

    First, ALL electronics devices will fail, just a matter of when. Now to limit the damage, I would get a good controller, but not over-kill unless you plan to get more solar panels. Once you get the new controller, install TWO fuses. One between the panel and charger and the other between the charger and battery. This will prevent the firework display you just had.
  • mike95490mike95490 Solar Expert Posts: 8,063 ✭✭✭✭✭
    Re: Solar Power Charge Controller Safety
    n3qik wrote: »
    Once you get the new controller, install TWO fuses. One between the panel and charger and the other between the charger and battery. This will prevent the firework display you just had.

    Maybe it will prevent it, maybe not. Electronics can fail, and go bad, and emit sparks, without causing a short. Also, a single PV panel may not even have enough power to blow a fuse, unless the fuse is right at the panel's limit. And the resistance introduced by the low current fuse itself, will reduce your solar output by a small amount, and is guaranteed to blow open in a year or so of use. (fuses used right at their limit, weaken and blow prematurely)

    Best to let someone in the Solar Electric industry look at the mess, or describe it here, with some photos possibly (in web resolution, not 6 megapix)
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    gen: ,

  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Solar Power Charge Controller Safety

    I was thinking of the current from the battery into the controller was the source of the sparks. Same for the one at the panel, as the battery is suppling the current.
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