Solar Controller Wiring

[SpeakEasy]

First let me begin by saying I am a weekend warrior. Dangerous to myself and my things because I'm always charging into projects without always completely knowing what I'm doing. I have always been that way, and I probably always will be. Such is life.

I have a Morningstar Sunsaver controller, and I am discovering that I've apparently wired it incorrectly. So - I would appreciate some help with answers to a couple of questions.

First - there is a "load" side of the controller. Am I correct in thinking that it has no function in a typical RV installation? My understanding is that the line from the solar panel comes in to the controller and the line out from the controller goes to the battery. Then all "load" comes directly from the battery. Am I correct? The "Load" side of the controller is unused?

Now - my bigger issue. When I was setting this up originally I was looking for the easiest way to make the connection from the controller to the battery without having to put more holes in the trailer. The controller is inside the trailer, and, of course, the battery is outside, on the A-frame of the tongue like most trailers. I knew that the lines from the battery already came through the trailer somewhere, and ended up at the circuit/fuse box for the whole electrical system. So, I reasoned that I could just tap in to the + line there, and that I could attach the - line to the negative bus bar. But then, in an effort to make my life even easier, I thought, "Why not just attach the + line to the + bus bar, on an unused, empty circuit, install a fuse, and I'm good to go.

Are you following me?

This actually did work. Apparently. The only bug was that my main disconnect switch no longer cut off the power. I wasn't really sure why, nor was I concerned enough about it to think about why. Again - everything else was working. Apparently. The indicator lights on the controller all behaved the way the manual said they should. My electrical systems all worked as they should.

Fast forward to now, when I'm winterizing. I want to disconnect the electrical system from the battery. Remember - my disconnect switch wasn't working? Well, I finally figured out why. I think. I think what's happening is with the + line coming from the controller to the + bus bar, I'm powering my whole trailer from the solar panel - above and beyond what's being supplied by the battery. Does this make sense? Am I allowing the battery charging line to function as a "Load" line for the whole trailer? And if so, am I causing damage to my electronics?

Thanks for helping me out. And please be kind in your responses. I already know I'm an idiot.

-Speak

[MrWizard]

Your existing wiring is fine for one panel
Including the back feed you did
The problem is the fact that the disconnect is basically inoperable and unusable
The wiring thing is mainly about voltage drop during charging
Since you are going to pull new wire
I would use wire large enough for any upgrade you might be considering for the future, like adding another panel or two

[SpeakEasy]

CA Traveler wrote:
You might want to run a wiring calculator to be sure you have adequate wiring for your equipment. Your setup charges and may be very adequate or perhaps improved.

The typical load output from a controller can supply power to other equipment when there is more power available than needed for charging or house loads. One poster was considering using a 12V hot water heater coil for "free" hot water.

I only have a 100-watt panel. Do you still think I should do these calculations? If so, can you give me some further instructions or point me in a direction to find out how this is to be done?

Thanks,
-Speak

[CA_Traveler]

You might want to run a wiring calculator to be sure you have adequate wiring for your equipment. Your setup charges and may be very adequate or perhaps improved.

The typical load output from a controller can supply power to other equipment when there is more power available than needed for charging or house loads. One poster was considering using a 12V hot water heater coil for "free" hot water.

[CA_Traveler]

My solar controller is wired to the charger/inverter which is wired to the batteries. The main consideration is that the wires are adequate in size which mine are. Disconnect switches are a consideration. I have switches on the controller panel input and the battery output. I also have a disconnect switch on the negative battery post. All switches are off while in storage.

[SpeakEasy]

I have the panel disconnected from the controller now, and I will re-wire it the conventional way.

When you say the preference is to have it "directly" connected to the battery, OK, I get that. But the way I've had it, it has been connected to the battery. (It's been connected to everything else too.) It has been charging the battery.

I was careful about the connection sequence so as not to go against the sequence that was detailed in the manual.

-Speak

[MrWizard]

speakeasy
yep.. you have it figured out
and as you have found out
some shortcuts cause problems, down the road

you need to rewire
or disconnect the solar panels from the controller and take the batteries inside for storage

there are good reasons for wiring the controller directly to the batteries

be mindful that most controllers must be connected to the batteries before connecting the panels

and the panels need to be disconnected from the controller before disconnecting the batteries from the controller

otherwise the controller will be damaged

my best guess, for your controller still working is because the TT wiring devices, presented a load, to use the current/amps from the controller
normally voltage spikes would kill the controller, disconnecting the batteries while the panels are connected and supplying power

[time2roll]

Yup you have it figured out. This why it is usually recommended to go from controller direct on the battery so the solar can maintain the battery even when the switch is opened for storage. The other issue is that controllers prefer to have a battery connected at all times. Apparently no issues with Sunsaver.

Do you expect the solar to maintain the battery in winter? I would not trust it the way you have it wired. You would have to leave the switch on. And with a few days or weeks of no solar the RV could flatten the battery.

And right there generally is no use for the load side of a controller with an RV. You could invent a use but it is not necessary.