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Vintage465's avatar
Nov 06, 2019

Circuit Breaker on Solar

I'm putting in some circuit breakers on my solar upgrade. Question is...on the breaker one side is Battery and one side is Auxiliary. My thought would be that the "input" or solar side would go on the "battery" post side of the breaker and the Auxiliary would then be hooked up to the side that goes to the battery. Now this is backward to the actual, "this is the battery and this is battery post". My thought is the power or higher amount is coming from the solar and it seems to me like that should get the "battery" post on the breaker. What are your thoughts?
  • I don't recall any polarity indication on my 80A DC CB. However the solar controller is the charge source and hence connect it to the battery terminal on your CB.
  • I did not realize a DC breaker had polarity. AC breaker does not care.
    I use a fuse from controller to battery just to protect the wire.
  • CA Traveler wrote:
    Not sure what you are asking. CBs are normally rated for amps. DC however is much more subject to contact arcing than AC. Panel wires typically connect to the solar controller input and the controller output connects to the battery. The controller may require a disconnect on both input and output.

    I used a 240V dual switch (typical AC switch for A/Cs) on my solar panel wires which carry 9A at 90V+. I used a 80A DC CB for the battery side.


    What I'm asking is this: All Circuit breaker have a "line" or "in" and and a "load" or "out". In any normal use of a circuit breaker the "line" or "in" post would be from the battery. On the circuit breaker the input post says "Battery". The "load" side says "Aux" and that is what goes out to what ever it is that puts load on the breaker. In a solar application....I see the Solar as the "Line" and the battery as the "Load". So I'd be running the solar into the "battery" side of the breaker and then out the Aux side of the breaker to the battery, as I see the battery as putting the load on the circuit.....
  • Not sure what you are asking. CBs are normally rated for amps. DC however is much more subject to contact arcing than AC. Panel wires typically connect to the solar controller input and the controller output connects to the battery. The controller may require a disconnect on both input and output.

    I used a 240V dual switch (typical AC switch for A/Cs) on my solar panel wires which carry 9A at 90V+. I used a 80A DC CB for the battery side.

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