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Combiner box

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Traviss224

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Jun 25, 2022
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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.

Thanks for the helpPXL_20220703_221221581.jpgPXL_20220711_225241803~2.jpgPXL_20220706_012606647.jpg
 
You haven’t mentioned what the equipment is that you are feeding with the panels. Is this a grid tie, hybrid or off grid system? What is the 50amp breaker for? Have you considered that you need fusing between the 3 series strings? If it was me and I had the room for the extra wire. I would probably home run each of the series strings to a combiner box close to the controller so I wouldn’t have so many connections on the roof to maintain.
 
I may recommend inside since it’s plastic. At least shaded somehow if not.

I can’t tell the quality of the box from the pic. I’m not a fan of plastics being in the sun year after year unless it is rated for it. It can crack and fall apart. I built a cable box for my RV roof out of a plastic project box. I think it will have a five year life based off how it’s holding up. I will paint it soon and it may hold out.

Perhaps this box is tough enough to hold up.
 
Bobert said:
You haven’t mentioned what the equipment is that you are feeding with the panels. Is this a grid tie, hybrid or off grid system? What is the 50amp breaker for? Have you considered that you need fusing between the 3 series strings? If it was me and I had the room for the extra wire. I would probably home run each of the series strings to a combiner box close to the controller so I wouldn’t have so many connections on the roof to maintain.
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It is an off grid system. I haven't considered fusing, as I thought that's what the combiner box is for. So basically fuse them and run 6 wires (3+ and 3-) to the combiner box in my shed?
 
With the combiner box having 10 amp fuses in it per line, is this not enough or should I also add an inline fuse between panels and combiner box?
 
Traviss224 said:
With the combiner box having 10 amp fuses in it per line, is this not enough or should I also add an inline fuse between panels and combiner box?
Click to expand...
One single properly rated overcurrent protection device per your three lines is all you need. So if the OCD is rated for the voltage, than only in line or in the combiner box, not both.

I remember the inline fuses and holders costing $10 to $15 each with the in the combiner fuse holder and fuses being more expensive. No harm in doing both, just expensive.
 
I thought these things were being phased out due to the newer chargers with high VOC and watt input.
 
Traviss224 you shoulda gone with the EG4s. I just preordered 2 6500ex's. Did not like my MPP, transformer sound annoys the heck out of me. Will be listing it for sale soon enough.
 
Lol too late now.. at least it shouldn't annoy me since it will be in the shed. Someone had recommended this one to me.. maybe Ian but I'm not 100%..
 
Traviss224 said:
Lol too late now.. at least it shouldn't annoy me since it will be in the shed. Someone had recommended this one to me.. maybe Ian but I'm not 100%..
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Yeah a shed is not good for equipment that is not made for outdoors. I'm hoping they warm up the house some.
 
nc73 said:
Yeah a shed is not good for equipment that is not made for outdoors. I'm hoping they warm up the house some.
Click to expand...
What do you mean, I plan on a solar shed? As long as the shed is built well, doesn't leak it should be fine.
 
nc73 said:
Yeah inverters put out good heat :) A shed is never airtight, and you don't want it airtight. If you don't mind dusting out the inverter on a reg basis, no problem. I like it where I can keep an eye on them. Stuff ain't cheap.
Click to expand...

Lots of folks build the sheds tight and insulate them..including the shipping container ones. Then they drop a split in them for the summer. It's the dam batteries that worry me. If you're rural...put a alarm system on it and monitor it for crack heads.
 
One of the other reason is I can keep it cooler in the house than in the shed. Not sure what temps folks are seeing with no AC.
 
nc73 said:
One of the other reason is I can keep it cooler in the house than in the shed. Not sure what temps folks are seeing with no AC.
Click to expand...
It got to about 108F this summer here in Texas outside...so yea I'd have to AC wherever they are. I'd really like to get a old shipping container and spray foam it inside then put a small split in it. I'm think of putting a damper in the container or shed wall and pipe that back to the house so in the winter I can pull warm air into the house and just circulate over and over with a small inline fan. Not sure if that would even be worth it but it's a idea.
 
Last edited:
chrisski said:
One single properly rated overcurrent protection device per your three lines is all you need. So if the OCD is rated for the voltage, than only in line or in the combiner box, not both.

I remember the inline fuses and holders costing $10 to $15 each with the in the combiner fuse holder and fuses being more expensive. No harm in doing both, just expensive.
Click to expand...
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.
 
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