Fuses for parallel solar array

[wrybread]

I'm helping a friend set up a solar array of 3 260-watt panels. I think they're 36 volt open circuit but I haven't seen them yet.

I'm going to wire them in parallel to give him the option of partial shading, and because his Tracer charge controller is 100 volts max.

I'm planning on using this branch connector, which gives room for another panel if he gets one:

Amazon.com

I'm planning to use these inline fuses on the branch connector:

https://www.amazon.com/Renogy-30-Waterproof-Line-Holder/dp/B00YG2IAQ4/

I'm wondering, do I need a total of 6 fuses (one on each positive and one on each negative) or is it enough just to put fuses on the positive lines?

Thanks for any help, and let me know if you have happen to have any suggestions for any of the above.

 

[timselectric]

Only need to fuse the positive.

 

[rmaddy]

You just need one set for the positive wires. The size of the fuse should be the same as the "Series fuse rating" found in the specs for the panels.

 

[timselectric]

Good catch
A 30 amp fuse is like not even having a fuse.

 

[Jack Rabbit Off Grid]

So are Panels like batteries that in my case 48.5v + 48.5v = 97v but my amps stay 11.42? My panels say maximum series fuse 25 amps. I’m going to wire mine 2s3p. Wouldn’t a 15amp fuse be better in my case?

 

[timselectric]

So are Panels like batteries that in my case 48.5v + 48.5v = 97v but my amps stay 11.42? My panels say maximum series fuse 25 amps. I’m going to wire mine 2s3p. Wouldn’t a 15amp fuse be better in my case?

Yes, 15A is what I would use.
25 is too high in my opinion.

 

[Jack Rabbit Off Grid]

Yes, 15A is what I would use.
25 is too high in my opinion.

Thank you.

 

[gnoeld]

Where would you place them? Close to where panels combine, the battery or in the middle?
Just one fuse or one for each panel?

 

[Rednecktek]

Where would you place them? Close to where panels combine, the battery or in the middle?

I've always seen them connect to the panel's Pos wire so it can protect the whole wire. If you did it near the end it wouldn't do the wire any good.

Granted, combiner boxes fuse the panels and those tend to be closer to the panel arrays as well.

Just one fuse or one for each panel?

In parallel you'd use one for each panel or each string of panels in his 2s3p configuration above.

 

[timselectric]

I would put the fuse at the branch connector.
One on each parallel string or panel positive.
The purpose of this fuse is to protect the string or panel from catching fire, if it develops a short.
If a short occurs, the amount of power from the other strings or panels is more than a single string or panel can handle.

 

[gnoeld]

Would the fuse go one for each panel or where they combine on the single wire?

 

[timselectric]

Each parallel string or panel.
Basically, every positive at the branch connector. (Except for the main wire, going to the SCC)

 

[gnoeld]

Each parallel string or panel.
Basically, every positive at the branch connector. (Except for the main wire, going to the SCC)

Thanks for clarification