Combiner box

[SpongeboB Sinewave]

A for the output of the combiner, a disconnect DC circuit breaker should be added, sized to protect that wire as well as being able to turn off the solar for servicing the equipment.

You do not want to have to unscrew a live wire every time you disconnect the PV. Maybe you knew this but I have seen where people actually disconnect the wires from their batteries and PV to change or service equipment. Very dangerous.

boB

 

[chrisski]

Technically you do not need a breaker for over current protection at all unless you are over paneling your controller. The solar panels are power limited and cannot over power the controller in a proper setup and will serve no protection purpose. (For starters the breaker is usual placed in the wrong place to protect wiring or the panels) But this is generally a technicality since a breaker is the most practical and cost effective way to turn off your solar array in order to service the controller. However If you have more than 2 series strings connected in parallel the combined output of 2 of the strings can overheat a shorted solar panel in the remaining string and potentially cause a fire. Therefore best practice is to fuse each series string just before they are combined together if you have mor than 2 strings. This is the main reason panels have a fuse rating so you don’t have to guess the proper size.

Since the OP has 3 sets of panels in parallel shouls he use some overcurrent protection on each string assuming max series fusing is exceeded?

 

[Phil.g00]

Your surge arrestors seem to be going to negative and not earth?

 

[Traviss224]

Your surge arrestors seem to be going to negative and not earth?

I'm not sure what you mean

 

[Phil.g00]

I'm not sure what you mean

I think the photo is a bit misleading, it looks like the negative is going into the Earth, but looking closely it isn't.

 

[Traviss224]

It was just an illustration of the panel Hook up

 

[Phil.g00]

 

[Old_Skewler]

Couple questions:

1. Should I put my combiner box on the roof with my panels or should it be in the shed with controller/ batteries? I'm assuming with the panels.

2. From my panels to my shed will be 25-30 foot of run. What wire size do I need?

3. From shed to my service hookup at the house will be about 10 feet. What size of wire do I need going there?

I'm running a growatt 6kw split phase system. I believe it needs a 50amp double pole breaker. Here are my solar panels. I'm running 6 in series, 3 rows in parallel. I think it's wrote at 6s3p. Please correct me if I'm wrong.

Did you finalize your install? I ask because I have a very similar condition (6S2P) arrays in the roof, shed about 30 feet away from the the roof. Slightly higher rated PV panels.

I am trying to decide whether to combine PV arrays at the roof (combiner box X MC4 splitters) or at the shed.

Could you share where your install stands as of now?

 

[Traviss224]

I have completed the install. I will try to post some pictures of it. I ran each of my series to my combiner box. I mounted My combiner box under my eave on the outside of where I put my AIO. My combiner box has fuses in it. I didn't put any additional fuses or anything. The run from panels to my combiner box is approximately 30'. From combiner box to my AIO control is approximately 6'. I'm not sure how much power total I am producing, as I was told my growatt doesn't show that, only what it is using. I have seen about 1.5 kw of power being used on the growatt. Feel free to PM me and I will be glad to help out in any way.

 

[Old_Skewler]

I have completed the install. I will try to post some pictures of it.

Glad to hear all went well. I have a very similar setup, actually I had the same GroWatt split-phase inverter but had to replace it with a Schneider.

Asides from that, similar PV array and shed layout.

Yes, If you could post or send me photos of the setup I would appreciate it. My goal is to close on the design this winter and install the PV gear early next spring.

 

[chrisski]

I am trying to decide whether to combine PV arrays at the roof (combiner box X MC4 splitters) or at the shed.

I recommend in the shed if the math works with the voltage loss. Makes troubleshooting so much easier not having to go to the roof

 

[SpongeboB Sinewave]

A breaker or fuse in the combiner that is typically put next to the PV array should have almost 0% chance of tripping.

IF a breaker or fuse DOES trip, then you have a bad connection or a shorted panel and are destined to go onto the roof anyway to fix the problem.

One of the big reasons to use a combiner, besides the over-current is so that you only have to bring down one pair of wires rather than a pair for every string or panel.

boB