DC or AC resettable breaker from panels to charger?

[MrMudstud]

My research indicates to use a fuse/breaker between the solars panels and charge controller. I was planning to run my panels in series, but now I think I want to run them in parallel because of possible more energy if any part of the panel has any shade. I was also thinking of using a resettable breaker to use as a switch if I wanted to isolate them if the need arises.

My questions are:
1. Do I need a DC or AC fuse/breaker?
2. What size fuse/breraker do I need, in parallel I think a 20 or 25 amp would work?

I have 2 panels of 270 watts a piece for a total of 540, and each panel is:
The Vmpp is 31.5 volt,
Impp is 8.58 amps,
Voc 38.5 volt,
Isc 9.17 amps.

Thank You in advance for your assistance, I really appreciate it.

 

[SolarRat]

25-30 amps should do, MUST be made for DC.

Debatable, but you might want a double pole vs single pole between the panels and CC.

 

[ghostwriter66]

My research indicates to use a fuse/breaker between the solars panels and charge controller. I was planning to run my panels in series, but now I think I want to run them in parallel because of possible more energy if any part of the panel has any shade. I was also thinking of using a resettable breaker to use as a switch if I wanted to isolate them if the need arises.

My questions are:
1. Do I need a DC or AC fuse/breaker?
2. What size fuse/breraker do I need, in parallel I think a 20 or 25 amp would work?

I have 2 panels of 270 watts a piece for a total of 540, and each panel is:
The Vmpp is 31.5 volt,
Impp is 8.58 amps,
Voc 38.5 volt,
Isc 9.17 amps.

Thank You in advance for your assistance, I really appreciate it.

Whats the max your SCC can handle ?? you want to max out the voltage before worrying about maximum amp or parallel

 

[SolarRat]

Whats the max your SCC can handle ?? you want to max out the voltage before worrying about maximum amp or parallel

Not if partial shading is a concern.

 

[JoeHam]

And oddly enough Square D makes two lines of breakers.

The QO series is rated for both DC and AC (only ones I know of).

Their Homeline series is AC only.

 

[Dzl]

My research indicates to use a fuse/breaker between the solars panels and charge controller. I was planning to run my panels in series, but now I think I want to run them in parallel because of possible more energy if any part of the panel has any shade. I was also thinking of using a resettable breaker to use as a switch if I wanted to isolate them if the need arises.

I think you are on the right track so far.

1. Do I need a DC or AC fuse/breaker?

Everything in your solar system will be DC up to the output side of your inverter.

2. What size fuse/breraker do I need, in parallel I think a 20 or 25 amp would work?

I have 2 panels of 270 watts a piece for a total of 540, and each panel is:
The Vmpp is 31.5 volt,
Impp is 8.58 amps,
Voc 38.5 volt,
Isc 9.17 amps.

I'm not the most qualified to answer this question, but I'll share what I've learned (and someone please correct me if I've mistated something).
Circuit protection between solar panels and the charge controller is a bit trickier than other connections because of the minimal ideal current (Impp) and the max current (Isc). In your case the Impp is roughly 17A and the Isc is roughly 18A. Normally to be effective against a short the breaker would need to be higher than 17A but lower than 18A, finding a 17.5A breaker is unrealistic and if you could find it nuisance trips would probably be an issue. For this reason some people choose not to fuse between PV array and SCC. But there are still reasons you may want to do so.

Here is one article that explains this in better detail.

Now, as I understand it, there is no downside to choosing a breaker larger than the Isc (short circuit current), like the 20 or 25 amp breaker you had in mind, it just won't offer any short circuit protection because a short in your solar wiring won't exceed the Isc. A breaker can be used as a switch to isolate your system from your PV array, and even if short circuit protection isn't a concern, lightning protection might be. I can't give any advice on that, I'm not informed or qualified to talk about lightning, but maybe someone else can.