Array Disconnect Switching Question-Mixed Arrays

Question

I have three different arrays on the roof with three different controllers that are in parallel to the battery bank. (It all works great.)

I do not have any array to controller switching. My three controllers don't seem to mind if the battery is disconnected, but I still want to have switching.

I can't figure out if it makes any difference if I combine the array to controller positives (or negatives) to one switch or if I need three switches.

With one, the three array pos wires would go to the switch and three wires output from the switch, one to each controller. One controller is PWM and two are MPPT but different models.

When all is running, the MPPTs have 30 or more volts to their arrays, but the PWM passes battery voltage at "12v" levels. Each MPPT could have a different voltage from the other's to its own array at any given time. I can't figure out if the correct three voltages will each reach its proper array if I use the one switch.

The three neg array wires would each still be going to its own controller, so does that still make three independent circuits for three different voltages?

Thanks.

wa8yxm · Answer

Simplest is 3 switches. but with 3 arrays and 3 controllers (one per array) the lovely thing about a DC system is .. They will work it out automatically.

bfl13 · Answer

So does that mean I can use one switch as described? (Reply not clear to me on that, sorry)

I am thinking of how the RV frame shares the "ground" (neg side) for both 120v and 12v, so my one switch could do three different voltages without messing them up. But I don't know.

time2roll · Answer

Single switch would require combining the arrays connections to the controllers. Are they combined now?

Otherwise I would be getting three switches. Maybe a single throw triple pole switch if you want one lever to pull.

bfl13 · Answer

time2roll wrote:Single switch would require combining the arrays connections to the controllers.  Are they combined now?Otherwise I would be getting three switches.  Maybe a single throw triple pole switch if you want one lever to pull.Each array has a pos wire and a neg wire that go directly to the array's own controller's array terminals.  One switch would combine the three pos wires, but the three neg wires would remain separate.The controllers are in parallel on the battery side so they add their amps (with the same controller Vabs settings), with the same "12v" on the three sets of those wire pairs.Yes, I would like to be able to turn off all solar with one "throw" instead of three "throws", but I don't know enough about the circuitry here.    If it matters, the panels are not "grounded" and the controllers are not "grounded", so that leaves the three neg array to controller wires independent.I have not checked whether the  controllers are all neg or pos "grounded" for which side they "control", but not sure that matters when the controllers are not grounded.  The battery bank is neg grounded to frame.

drewe · Answer

If the controllers (or at least two of them) isolate the panel negative from the battery negative, the single switch should in theory work. If the controllers do not isolate the panel negative from the battery negative/ground, it will not work. I would go with three separate switches if possible, as switches are not all that expensive all things considered and there's no question that it will work and it gives you a little more flexibility should that need come up.

(A suitable fuse that can be pulled is also a possible disconnect option.)

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Array Disconnect Switching Question-Mixed Arrays

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