What size fuse is prudent in this situation?
Or, are fuses even required?
2 systems on a single house roof feeding 2 meters.
2 strings to one inverter feed one meter and 1 string to another inv. and meter.
All three strings go to a single combiner box on roof. The first 2 strings are combined, while of course the third remains separate. They proceed to a single conduit (even though separate systems) down from there to two dc discos, one for each system. The first two strings are combined into a #10. The remaining uncombined circuit is #12.
Source circuit: 5.62 A Isc
(@156% = 8.78A)
Max series fuse rating from spec sheet : 10 A. That sucks.
1@10 A fuses on each of three strings. (grounded system, so single fuse on positive conductors only)
Now, were it three strings combined to one combined output circuit, clearly fuses are required. But here?
I would love to just put in some higher Amp fuses. Not really for over current protection, but to complete circuit and be done.
This is assuming fuses were not needed. Otherwise I do not know how I may exceed panel rating of 10A........
Say 15 or 20 or even some 12's i have left over.....kinda like a solid metal slug.
In general, I have been finding that after several years in operation, and using the smallest allowable fuse size in a rooftop comb. box, it results in nuisance burn outs and troublesome replacements of fuses.
In all cases the fuses were sized above 156% Isc.
(In one case 12 A fuses were appropriate (about 7 or so A Isc) but burned out so i replaced with 15A as wiring and max series fuse rating allows 15A.)
Or, are fuses even required?
2 systems on a single house roof feeding 2 meters.
2 strings to one inverter feed one meter and 1 string to another inv. and meter.
All three strings go to a single combiner box on roof. The first 2 strings are combined, while of course the third remains separate. They proceed to a single conduit (even though separate systems) down from there to two dc discos, one for each system. The first two strings are combined into a #10. The remaining uncombined circuit is #12.
Source circuit: 5.62 A Isc
(@156% = 8.78A)
Max series fuse rating from spec sheet : 10 A. That sucks.
1@10 A fuses on each of three strings. (grounded system, so single fuse on positive conductors only)
Now, were it three strings combined to one combined output circuit, clearly fuses are required. But here?
I would love to just put in some higher Amp fuses. Not really for over current protection, but to complete circuit and be done.
This is assuming fuses were not needed. Otherwise I do not know how I may exceed panel rating of 10A........
Say 15 or 20 or even some 12's i have left over.....kinda like a solid metal slug.
In general, I have been finding that after several years in operation, and using the smallest allowable fuse size in a rooftop comb. box, it results in nuisance burn outs and troublesome replacements of fuses.
In all cases the fuses were sized above 156% Isc.
(In one case 12 A fuses were appropriate (about 7 or so A Isc) but burned out so i replaced with 15A as wiring and max series fuse rating allows 15A.)