4S3P Configuration- Combiner Box or Fuses?

[PaulLad]

I've got 3 strings of 4-100 watt panels in series. Not sure I understand when fuses are ok and when a combiner box is needed instead. Any insight is appreciated.

 

[sunshine_eggo]

I've got 3 strings of 4-100 watt panels in series. Not sure I understand when fuses are ok and when a combiner box is needed instead. Any insight is appreciated.

4S3P

It's preference. Either one works if specs are met. The requirement is that 3 or more strings must have each string with over current protection (OCP), i.e., fuses or breakers, and no component specs are exceeded.

The super easy mode would be 3 into 1 MC4 connectors with a single MC4 fuse on each (+) string.

Since each string likely only produces about 6A max, one 10A MC4 fuse on each string would work. MC4 connectors are rated for 30A, and your array is certainly less than 20A, so that works too.

 

[PaulLad]

Thanks. I thought at minimum I would need a fuse on each panel. You just saved me quite a bit of money.

 

[sunshine_eggo]

Thanks. I thought at minimum I would need a fuse on each panel. You just saved me quite a bit of money.

You're still probably looking at $40-60 of connectors and fuses, but their "mounting" is dramatically easier.

 

[PaulLad]

You're still probably looking at $40-60 of connectors and fuses, but their "mounting" is dramatically easier.

So just a 3 way mc4 combiner and 3 fuses. $50. That's a lot better than the $120 I expected.

 

[sunshine_eggo]

https://www.amazon.com/BougeRV-Connectors-Branch-Parallel-Adapter/dp/B08FLGCYPD

$16

https://www.amazon.com/ZOOKOTO-Solar-Panel-Connector-Waterproof/dp/B0825H3KDM (5 pack, only need 3)
$19