Solar Panel Circuit Breakers

[Larry S]

I'm using 4 solar panels in series with an Isc of 5.7 amps. Is it a "problem" to use a 20 A breaker?

 

[BiduleOhm]

No, in series the current stay the same and the voltages are cumulative.

In parallel it's the opposite; currents are cumulative and voltage stay the same.

 

[tictag]

Personally, I wouldn't bother fusing it, just make sure your PV cable is rated for Isc.

Isc is the MAXIMUM current that could ever flow in the cable, even if were shorted. Why fuse it? I could fart more than 5.7A.

Isolator switch, yes, and if this is what your using the breaker for then OK.

Edit: Added isolator switch clarification.

 

[Sgt Raven]

No, in series the current stay the same and the voltages are cumulative.

In parallel it's the opposite; currents are cumulative and voltage stay the same.

Which is different from resistance for a speaker circuit.
Two 8 ohm speakers in Series is a 16 oh load to the amp.
Two 8 ohm speakers in Parallel is a 4 ohm load to the amp. You can carry this out, too. 3 at 8 ohms is 2.67 ohms, 4 at 8 ohms is 2 ohms.

 

[Sgt Raven]

Which is different from resistance for a speaker circuit.
Two 8 ohm speakers in Series is a 16 oh load to the amp.
Two 8 ohm speakers in Parallel is a 4 ohm load to the amp. You can carry this out, too. 3 at 8 ohms is 2.67 ohms, 4 at 8 ohms is 2 ohms.

OFFS, Will... I was watching this video Will made. At the 4:44 mark he has twisted the leads of two large resistors together and using them to dischagre a cell in a battery.. By doing that he has cut the resistance in half. He should have put them in series.. Even Will makes mistakes... LOL..

 

[BiduleOhm]

I don't think it was a mistake. He probably wanted to discharge the cell quicker and to do that you need a higher current, so a lower resistance.

 

[Sgt Raven]

I don't think it was a mistake. He probably wanted to discharge the cell quicker and to do that you need a higher current, so a lower resistance.

Like I've said in other threads. I've been out of the electronics/electrical theory game for a long time. I was thinking more resistance would use more power, faster. Most of the stuff I've done in the last 40 years was either hooking things, like radios or lights up, or finding a fault in an existing circuit. I've probably forgotten 87% of what I learned in school, from lack of use.

 

[Sgt Raven]

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But then you have State regulators and the Power Companies that lobby them and you end up with a law. 1. your solar must be grid tied and 2. you can't use your solar power when the grid is down. That is what happened in Florida after Hurricane Irma. I remember reading about it back then and went and found a link about it.

https://interestingengineering.com/...ng-solar-power-in-aftermath-of-hurricane-irma