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Old 14-03-2017, 13:24   #1
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Break Pos or Neg on Solar Panel wire to controller

I would like to have my solar panels able to be turned off to the controller for any number of reasons. One main one is that my controller wants no V in when connecting/disconnecting to the battery. It is PITA to get to the little screws connecting the wires to the controller, so just wanting to do that means unconnecting the panels from the controller.

Having a switch/breaker would be much better. I purchase the blue seas breaker
https://www.bluesea.com/products/cat...ers/285-Series

Was planning on putting this on the POS wire from the panel to the controller. Then an electrical person at the yard said to break the NEG? I know about electron flow etc., but doesn't it make more sense to break the POS in this case.

Thanks
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Old 14-03-2017, 13:34   #2
rom
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Re: Break Pos or Neg on Solar Panel wire to controller

Quote:
Originally Posted by jbinbi View Post
I would like to have my solar panels able to be turned off to the controller for any number of reasons. One main one is that my controller wants no V in when connecting/disconnecting to the battery. It is PITA to get to the little screws connecting the wires to the controller, so just wanting to do that means unconnecting the panels from the controller.

Having a switch/breaker would be much better. I purchase the blue seas breaker
https://www.bluesea.com/products/cat...ers/285-Series

Was planning on putting this on the POS wire from the panel to the controller. Then an electrical person at the yard said to break the NEG? I know about electron flow etc., but doesn't it make more sense to break the POS in this case.

Thanks
And he didn't say what difference does it make ? too bad that would have been interesting ...

I think it is common use to have a double pole switch so you can totally isolate the panel in case of thunder. That's how I did it.
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Old 14-03-2017, 13:36   #3
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Re: Break Pos or Neg on Solar Panel wire to controller

thanks. didn't care to put in a dp switch, was just looking for convenience. He did not say why, and I didn't care to discuss with him.
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Old 14-03-2017, 14:02   #4
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Re: Break Pos or Neg on Solar Panel wire to controller

rom, which brand did you use?
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Old 14-03-2017, 14:12   #5
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Re: Break Pos or Neg on Solar Panel wire to controller

fwiw, I put this between my panels and controller

Modular DC Disconnects [SI16-DBL-2] : Industrial Control Direct

enclosed models available if you prefer....
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Old 14-03-2017, 14:24   #6
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Re: Break Pos or Neg on Solar Panel wire to controller

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rom, which brand did you use?
I use something that has no name and was not meant for that use I just made sure it had the required specs, which in my case is 100+ Volts and 80+ amps. I shall change it to something more conventional.

Dotdun just gave you an excellent example of what to use !
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Old 14-03-2017, 14:39   #7
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Re: Break Pos or Neg on Solar Panel wire to controller

Thanks. Didn't see the post, was searching myself. Found maybe just a din rail breaker like this

https://www.amazon.com/uxcell-6000A-...+rail+breakers

285 w panel, 40V OC, so maybe 8A Isc. This should be OK I would think, and it's $10...
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Old 14-03-2017, 14:51   #8
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Re: Break Pos or Neg on Solar Panel wire to controller

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Originally Posted by jbinbi View Post
Thanks. Didn't see the post, was searching myself. Found maybe just a din rail breaker like this

https://www.amazon.com/uxcell-6000A-...+rail+breakers

285 w panel, 40V OC, so maybe 8A Isc. This should be OK I would think, and it's $10...
You do not need a breaker, you need a switch. I am not sure a breaker is as good a switch as ... a switch
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Old 14-03-2017, 15:02   #9
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Break Pos or Neg on Solar Panel wire to controller

I used fuses, they open up to disconnect, actually I used a combiner box that has a lightning arrestor and fuses.
I believe the flow of electricity is from negative to positive, if so the Brits had it right with their old cars
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Old 14-03-2017, 15:21   #10
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Re: Break Pos or Neg on Solar Panel wire to controller

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Originally Posted by jbinbi View Post
Thanks. Didn't see the post, was searching myself. Found maybe just a din rail breaker like this

https://www.amazon.com/uxcell-6000A-...+rail+breakers

285 w panel, 40V OC, so maybe 8A Isc. This should be OK I would think, and it's $10...
It doesn't say it's rated for DC.
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Old 14-03-2017, 22:39   #11
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Re: Break Pos or Neg on Solar Panel wire to controller

Your best option is to cover the panels. Or work at night... I don't think you want to break that connection from panel to controller while they are producing.
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Old 14-03-2017, 23:11   #12
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Re: Break Pos or Neg on Solar Panel wire to controller

I believe with solar panels you can safely just short them to stop output?
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Old 15-03-2017, 05:57   #13
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Re: Break Pos or Neg on Solar Panel wire to controller

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Your best option is to cover the panels. Or work at night... I don't think you want to break that connection from panel to controller while they are producing.
What would you expect ? I do break the connection from time to time when working on my electrical system. Never heard of that being wrong... From my understanding panels can be open or short circuit in full sun no problem.
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Old 15-03-2017, 06:27   #14
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Re: Break Pos or Neg on Solar Panel wire to controller

well of course you break the connection when they are producing. when they ship to you or they have not been installed, they are producing and the 2 leads are open.

I think in my case an AC breaker is OK. I am not using it as a breaker, but rather a switch. breakers work by heat, the internal strip gets too hot when too much current is pulled the metal expands, tripping a spring to shut the breaker. If a 120V 15A breaker can handle about 1500 watts, and my solar panel is putting out 40V @ 7A, this should be fine. So I am not relying on it to actually trip by itself, just me shutting it off. But if I can find a DC din rail breaker, it would be better...
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Old 15-03-2017, 06:37   #15
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Re: Break Pos or Neg on Solar Panel wire to controller

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well of course you break the connection when they are producing. when they ship to you or they have not been installed, they are producing and the 2 leads are open.

I think in my case an AC breaker is OK. I am not using it as a breaker, but rather a switch. breakers work by heat, the internal strip gets too hot when too much current is pulled the metal expands, tripping a spring to shut the breaker. If a 120V 15A breaker can handle about 1500 watts, and my solar panel is putting out 40V @ 7A, this should be fine. So I am not relying on it to actually trip by itself, just me shutting it off. But if I can find a DC din rail breaker, it would be better...
DC arcs more than AC, the contacts in a switch/breaker get burnt far easier/quicker interrupting DC than AC, hence the typically lower DC rating on dual purpose devices. Long term use of a device not made for DC *could* cause high joints across the contacts.

I would use a device that is rated for your system. YMMV
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