Solar system fuse

[JPMaly]

Installing solar system. 2 100 watt panels go power controller that powers both the house and chassis batteries. House has 2 100 ah batteries and the chassis has one battery, looks like group size 27, probably 100 ah. What size fuse do I need for both lines? Manual states both operating and short circuit is 37.5 amp. Max fuse is 50 amp. As you can tell, both me and my post are confused.

[Dutch Star Don]

I used a good quality resettable circuit breaker like the one listed below. One on the (+) side of the solar wiring and one between the controller and batteries. The large fuses are hard to handle and deal with.

https://www.amazon.com/Tocas-Surface...s%2C242&sr=8-3

[twinboat]

You fuse to protect the wiring.

Fuse size depends on what size wires you are using. Of course you need to wire it for more then the total solar output.

Keep the fuses near the batteries because they can melt the wire in seconds if shorted.

Fusing between 2 panels and the controllers isn't critical. The fuse will need to be rated higher then the solar output and never blow anyway. A switch will come in handy though.

With 2 100 watt panels, you can use a 20 amp fuse on each line to the batteries. Your panels will only make about 16 amps on a perfect day.

[JPMaly]

Thanks for the replies. I used 4 gauge wire. Could I use a larger amp breaker now, say 40 or 50 amp, and add more panels later?

[twinboat]

If your wired for 50 amps, yes you can.

[JPMaly]

Thanks!

[153stars]

Ampacity chart.
https://www.cerrowire.com/products/r...pacity-charts/
Depends on wire type wire used. In your case I would keep rated to suggested input /rating of charger until upgrading higher rated unit. We have used special nickel plated fine strand high temp 10ga wire at work than can carry 70amps .


https://www.cerrowire.com/products/r...pacity-charts/