How to size DC breaker 4x 100 watt panels to 40amp SCC?

[Smeeg]

4 x 100 watt panels in series going to 40amp SCC I understand I don’t really need a fuse or breaker but I want a way to disconnect the panels from the SCC near the SCC. Was planning on using a two pole dc breaker but don’t understand how to size it? Also in the future I plan to add more panels (24v battery bank, using 10awg PV wire)

HSQ 100 watt panel
VOC= 21.6v
VMP=17.9v
lmp=5.72A
lSC=6.24A

EPEVER MPPT Solar Charge Controller 40A 150V Tracer4215BN max PV input: 24v 1040W​

 

[Rednecktek]

The math is usually Amps * 1.25 so about 7a for your string, although good luck finding a breaker below about 10a or so. If you are going to be paralleling in more panels you can go for a 15a now and be ahead of the game.

 

[Smeeg]

The math is usually Amps * 1.25 so about 7a for your string, although good luck finding a breaker below about 10a or so. If you are going to be paralleling in more panels you can go for a 15a now and be ahead of the game.

A 10amp & 40amp are the same price what’s the downside of oversizing? I’m not actually protecting the wires then? I was thinking about using a 10amp inline fuse holder near the panels(to protect the wires) then using a 40amp breaker near the SCC used as a disconnect?

 

[Supervstech]

A 10amp & 40amp are the same price what’s the downside of oversizing? I’m not actually protecting the wires then? I was thinking about using a 10amp inline fuse holder near the panels(to protect the wires) then using a 40amp breaker near the SCC used as a disconnect?

If you install a 40A breaker, the wire needs to be #8… unless it’s a motor load circuit, then it could be #12… but #10 would be a happy medium…

 

[Smeeg]

If you install a 40A breaker, the wire needs to be #8… unless it’s a motor load circuit, then it could be #12… but #10 would be a happy medium…

The wire chart I’m reading says #10 wire is rated for 30amps so maybe I should use a 25amp breaker?

 

[ungrounded]

The wire chart I’m reading says #10 wire is rated for 30amps so maybe I should use a 25amp breaker?

You can use anything up to and including the 30amp. #10 wire is rated 30 amp.