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I have bought a 12 V, 80 W solar panel and before I start using it I want to install circuit breakers between the solar panel and the charge controller, the charge controller and the battery, and the battery and the inverter to protect all the components involved.

With the research that I have done I should be buying two 10 A DC circuit breakers, one for solar panel to charge controller and the other from charge controller to battery, and a 30 A between the battery and the inverter.

What I'm confused about is if I should be buying 12 V circuit breakers as I have seen some circuit breakers with a max voltage of 250 VDC. Will this do, or should the circuit breakers only be 12 V as this is a 12 V system?

Also, should I be buying 1-pole or 2-pole circuit breakers? Since it is a 12 V, 80 W solar panel I think 1 pole should be fine but I'm not sure.

If anyone could point me in the right direction it would be much appreciated.

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    \$\begingroup\$ Draw a schematic and indicate where the breakers should be. Explain what nominal and full-load currents are expected and explain what part of your system's infrastructure (including modules) requires overload current protection. Link all device data sheets please. \$\endgroup\$
    – Andy aka
    Commented Oct 21, 2022 at 9:04
  • \$\begingroup\$ Circuit breakers are rated according to AC/DC current. The voltage rating really just tells you what they can safely handle in terms of insulation so a higher voltage rating than you need isn't a problem. \$\endgroup\$
    – Finbarr
    Commented Oct 21, 2022 at 11:09
  • \$\begingroup\$ It's important to note the breakers' DC voltage rating as this is usually far lower than their AC rating. At 12V this is unlikely to matter but it's a good general point to note. \$\endgroup\$
    – Russell McMahon
    Commented Oct 21, 2022 at 11:24
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    \$\begingroup\$ I can see you have specified DC breakers in your question, but I do want to emphasize that point - your breakers must be rated for use with DC to be used safely here. Many AC breakers rely on the zero-crossing in the waveform to help extinguish the arc when they trip - but DC has no such waveform. AC rated breakers might fail to break the circuit speedily (or at all) when used in a DC circuit. \$\endgroup\$
    – brhans
    Commented Oct 21, 2022 at 13:14
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    \$\begingroup\$ We can answer this question if you supplly the imput asked for by various people. Otherwise its too open ended to be able to help you usefully. \$\endgroup\$
    – Russell McMahon
    Commented Jan 1, 2023 at 3:15

2 Answers 2

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You may consider using in-line fuses.

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  • \$\begingroup\$ It is possible that the solar panel might not need protection. They are inherently current limited and as long the wiring can handle the short circuit current, there should be no problem. But the OP should supply a schematic and parts identification as requested. They may have sufficient internal protection, and circuit breakers might just be needed for disconnect switches. \$\endgroup\$
    – PStechPaul
    Commented Jan 16, 2023 at 3:32
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Shorting a solar panel does it no harm, and the normal operating current in full sun is perhaps 90% of the short circuit current. Wire and circuitry that can handle the normal current should thus be able to handle anything the panel delivers. A circuit breaker, unless perfectly sized to the panel, will either never trip or trip needlessly. So you don't normally put a circuit breaker on a solar panel.

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