basic solar diagram

I used this manual reset circuit breaker between modules and controller. I used a slow blow fuse of 25A between controller and batteries.

I used these 20 amp fuses at the PV panels because:
1. They were free.
2. See 1 above.
I don't think they are needed.

deprived wrote:
I found this chart.

http://assets.bluesea.com/files/resources/newsletter/images/DC_wire_selection_chartlg.jpg


If I am reading this correctly (and it's likely I'm not) the run from the controller to the battery should be a 100amp fuse. Am I getting this?

That sounds reasonable to me.

Realistically, if the wire is only for the solar charging, you could equally well use a smaller fuse if you wanted to, though there's no particular reason to want to do so. The fuse should, of course, be larger than the maximum charge current produced by the solar setup. What you don't want is a fuse larger than the safe current carrying ability of the wiring.

I found this chart.

http://assets.bluesea.com/files/resources/newsletter/images/DC_wire_selection_chartlg.jpg


If I am reading this correctly (and it's likely I'm not) the run from the controller to the battery should be a 100amp fuse. Am I getting this?

pianotuna wrote:
and should be sized for the gauge of wire that is being used.

Yeah - that's the part I'm asking about.

Personally I would not fuse between the panels and the controller. I would have a dc rated switch instead.

The fuse from the controller to the battery bank should be as near to the batteries as possible and should be sized for the gauge of wire that is being used.

I've made a few small changes to my plan - the battery sets are about two feet from each other and will be connected by 4awg wire.

I'm not sure what size fuses, though. I have 3 100w panels (but I'll probably add a 4th) that are connected with 10awg. The run is fairly short - about 6 feet. The controller, a 40 amp Renogy, is connected to the batteries with 4awg wire. The run is maybe 30 inches.

All connections are crimped, soldered and wrapped because I love using my torch. I so rarely get to play with it.

So I'm thinking 30amp fuse on the panels and 40amp fuse on the batteries. Does that sound right?

Thanks. Sometimes the rules are made-up stuff.

If a circuit has a 15a rating and you have 25 amp supply then yes that is the reason for a fuse.
Chance of actual fault is probably zero. Most likely any fault would be an open circuit and solve the issue before it even exists.
I don't make the rules. Is what it is.

smkettner wrote:
Although a failed panel (shorted?) would absorb Isc from a pair.

That's the reason for fuses?