Single String Combiner Box for Fuse, Breaker, Lightning???

[WattAboutThat]

I am installing Two (2) EG4 18kPV Inverters.
I am going to put Three (3) Strings to each inverter.
One string to each MPPT (MPPT 1,3,4)
Not using MPPT 2 (which is paralleled internally to MPPT 1).
Each string will have TEN (10) Canadian Solar all black 385W panels in Series, each panel is
43.9V and
11.32A.

I am not paralleling any strings.

I would like to have a combiner box
(even though not combining, just for preventive safety) at the solar array to protect from lightning and to have a breaker before it travels to the inverters.

So I am looking for
a single string combiner box,
that will have fuse, breaker, and lightning protection for each string, then send down the wires to inverter (which has an internal breaker).

So I am not sure if it would still be referred to as a combiner box.

I dont mind if it is a larger box that can have 6 strings in one box going in and 6 strings going out, I am mainly looking to have protection for the system, before it reaches the inverter(s).

I have searched with little luck.

My best bet so far is to get a Two String In, One String Out Combiner and just not use the extra string input. This would then require 6 of these.

I am requesting advice, ideas, where to purchase something for this purpose.

Thank you for your assistance.

 

[Adam De Lay]

These would take some reconfiguring because they’re actually designed to be combiner boxes, but might work for what your looking for.

PV Combiner Boxes – Watts247 Wholesale

watts247.com

 

[Zwy]

Built my own even though I have a 4 to 2 combiner from Ian at Watts247.

Vevor box and IMO disconnect, used chase nipples and Meyers hub between IMO and box, like this video:

You want a disconnect that is accessible, the Vevor is lockable and needs a "key" to open it.



Inside the box, just source some DIN rail, then breakers and surge protectors on the DIN.

 

[timselectric]

Just add breakers and arrestor.


Tulabu Waterproof Breaker Box Distribution Protection Box, IP66 PC/ABS Alloy Plastic Distribution Protection Box with Clear Cover and DIN Rail, for Indoor and Outdoor(12 Way) https://a.co/d/gg99mxi

 

[WattAboutThat]

So I think, for this build (since it is my first),
I will likely go with Four (4) of the 4 to 2 boxes from watts247.

Even though i will only use 2 strings in 2 of the boxes and one string in 2 of the boxes.

I may reduce that to Three boxes, but not sure if the Arrays will be in one row or two.

I am reasonably confident I could build my own in a future build, but my brain is becoming overwhelmed with things to consider and compare. And this is the easier solution for now.

Thanks to everyone for all of the great advice.

This forum is invaluable!!!

I intend to offer more once I have more experience.

 

[solarhombre]

Built my own even though I have a 4 to 2 combiner from Ian at Watts247.

Vevor box and IMO disconnect, used chase nipples and Meyers hub between IMO and box, like this video:

You want a disconnect that is accessible, the Vevor is lockable and needs a "key" to open it.

View attachment 150181

Inside the box, just source some DIN rail, then breakers and surge protectors on the DIN.


View attachment 150182

I am about to do something similar and was wondering if i can insert 2 wires into the breaker inputs as you do here. Would that pass an inspection or would they complain about double tapping?

Asking because I have purchased a dinkle assembly (Dinkle Assembly Kit DK6N Red/Black 10 Gang with Jumpers DIN Rail Terminal Blocks, 8-20 AWG, 50 Amp, 600 Volt https://a.co/d/ewpdiEf) and was planning on using 1 wire input and 2 blocks connected with a jumper, with the 2 output wires going 1 to the breaker and 1 to the SPD.

Another option I am considering is using a twin 10AWG ferrule, but unsure about crimping solid wire. This would definitely take less space in the box.

 

[ksmithaz1]

Everybody likes to oversize the small wires and undersize the really big ones. I also built my own surge box, which I am re-engineering because I have to move it outside with the 18K inverters . . . ran out of space on my rock board wall. The MC-4's will go away, and I'll run it in from 3/4 flex with a drip loop at the bottom. I'm running 12awg THHN, so 16A or less sustained current in flex conduit to j-boxes on the roof with MC-4's. The roof conduit is 1/2" to the final box, then 3/4 down to this. I built it to support 6 strings, I will start with 4.

 

[solarhombre]

Would you be able to take a pic showing the dinkle connectors between breaker and SPD in more detail? TIA.

I think i also have the same box (Vevor NEMA 4 12x12?) and seeing how you arranged everything resolved all my doubts. Thanks!

 

[ksmithaz1]

This is a 16x16x6 Steel IP66 rated cabinet. I bought another to replace the one with the MC4's at the top that was inside, I had to re-engineer the entire setup when I got the 18K's. I stole the plate / breakers out of the original, and just mounted it in the new box. I bought DIN rail and put two rows down along with some 20A DIN bus connectors. The feed back to the Inverters will be into the bottom of the 2R2B bus blocks between the breaker and the surge protector. I'm really kind of pissed I got 2 white and 4 red surge protectors, I'm probably a little too anal about looks, but this is all #12 THHN stranded wiring. I could not get a ferule on the end, so it's just tucked in stranded.
You'll note 15A breakers. I'm kind of cautious about de-rating service. The panels are rated at 10.5ish amps, reality is they likely won't actually get that high even, so 15A is good for 12A continuous, and if something slowly creeps to danger I'd rather it just shut on down. This will also be my shutoff. Breakers are cheap, and fine as a switch if you are not turning it on/off very much.
In the lower pic you can see the box on the wall fed from the boxes on the roof. I also dropped a new ground rod, in the corner. My circa 70's house is apparently using the feed cable conduit pipe as groundt and while not awful, I prefer an 8' rod. Was not as hard to drive as I thought it was going to be. I'll tie the grounds together and keep the G/N bond in the main (150A) panel. Might drop another on the other side of the panel, haven't decided yet soil here seems pretty decent for ground unlike the NC sand hills I've grounded in the past. Any way will bring a ground up inside, and I still have to knock a 3/4 pipe thru the wall. Inverters are on the other side.

 

[solarhombre]

This is a 16x16x6 Steel IP66 rated cabinet. I bought another to replace the one with the MC4's at the top that was inside, I had to re-engineer the entire setup when I got the 18K's. I stole the plate / breakers out of the original, and just mounted it in the new box. I bought DIN rail and put two rows down along with some 20A DIN bus connectors. The feed back to the Inverters will be into the bottom of the 2R2B bus blocks between the breaker and the surge protector. I'm really kind of pissed I got 2 white and 4 red surge protectors, I'm probably a little too anal about looks, but this is all #12 THHN stranded wiring. I could not get a ferule on the end, so it's just tucked in stranded.
You'll note 15A breakers. I'm kind of cautious about de-rating service. The panels are rated at 10.5ish amps, reality is they likely won't actually get that high even, so 15A is good for 12A continuous, and if something slowly creeps to danger I'd rather it just shut on down. This will also be my shutoff. Breakers are cheap, and fine as a switch if you are not turning it on/off very much.
In the lower pic you can see the box on the wall fed from the boxes on the roof. I also dropped a new ground rod, in the corner. My circa 70's house is apparently using the feed cable conduit pipe as groundt and while not awful, I prefer an 8' rod. Was not as hard to drive as I thought it was going to be. I'll tie the grounds together and keep the G/N bond in the main (150A) panel. Might drop another on the other side of the panel, haven't decided yet soil here seems pretty decent for ground unlike the NC sand hills I've grounded in the past. Any way will bring a ground up inside, and I still have to knock a 3/4 pipe thru the wall. Inverters are on the other side.

View attachment 154406


View attachment 154407

It looks great!

Seeing the actual space those breakers+SPDs take, I will get a 16"x16" box and return the 12x12.

In my case I want to run 10 AWG THHN/THWN-2 from the garage where my off-grid inverters are to the south wall where the grid-tied inverter is. I will use the box to select which inverter(s) get the PV inputs, but it will normally be the grid-tied one except for outages, and maybe full sun days. I don't anticipate to be switching the breakers on and off often, and I'm still going back and forth on whether I should add SPDs in the garage and outside for the off-grid inverters since they won't be getting PV input that often.

The Dinkle terminal blocks are rated for 2 conductors with the same cross-section, but I might get DK4N and just double them up with a jumper instead as you did. It looks better and maybe safer too.

Thanks a lot for posting the pics and details of what you are doing.

 

[ksmithaz1]

You'll probably want to bump to the bigger dinkle if you use #10. May make the space a little tight. I wanted to make sure I had an easy ground bus to get to.

 

[SniperX]

This is a 16x16x6 Steel IP66 rated cabinet. I bought another to replace the one with the MC4's at the top that was inside, I had to re-engineer the entire setup when I got the 18K's. I stole the plate / breakers out of the original, and just mounted it in the new box. I bought DIN rail and put two rows down along with some 20A DIN bus connectors. The feed back to the Inverters will be into the bottom of the 2R2B bus blocks between the breaker and the surge protector. I'm really kind of pissed I got 2 white and 4 red surge protectors, I'm probably a little too anal about looks, but this is all #12 THHN stranded wiring. I could not get a ferule on the end, so it's just tucked in stranded.
You'll note 15A breakers. I'm kind of cautious about de-rating service. The panels are rated at 10.5ish amps, reality is they likely won't actually get that high even, so 15A is good for 12A continuous, and if something slowly creeps to danger I'd rather it just shut on down. This will also be my shutoff. Breakers are cheap, and fine as a switch if you are not turning it on/off very much.
In the lower pic you can see the box on the wall fed from the boxes on the roof. I also dropped a new ground rod, in the corner. My circa 70's house is apparently using the feed cable conduit pipe as groundt and while not awful, I prefer an 8' rod. Was not as hard to drive as I thought it was going to be. I'll tie the grounds together and keep the G/N bond in the main (150A) panel. Might drop another on the other side of the panel, haven't decided yet soil here seems pretty decent for ground unlike the NC sand hills I've grounded in the past. Any way will bring a ground up inside, and I still have to knock a 3/4 pipe thru the wall. Inverters are on the other side.

View attachment 154406


View attachment 154407

I really like your clean-looking setup. My OCD appreciates the work you put into it. Do you mind sharing a link where you purchased the box and the breakers? I need to do something like this. So, you just flip all the breakers or do you have an external cut-off switch as well?

 

[Hedges]

I would like to have a combiner box
(even though not combining, just for preventive safety) at the solar array to protect from lightning and to have a breaker before it travels to the inverters.


that will have fuse, breaker, and lightning protection for each string, then send down the wires to inverter (which has an internal breaker).

I think lightning protection at PV array may cause more harm than good.

If nearby lightning induces current in wires of PV array, they get clamped to ground at the combiner box. All good there.

If lightning induces current in home run wires from array to inverter, the end of wires at combiner box get clamped to ground, while end at inverters swing wildly, causing over-voltage damage.

If lightning hits the ground nearby, current spreads out in all directions. When it reaches array if triggers lightning "protection" to reach copper wires, which are much lower resistance than earth, and flows through the wires into your inverters, causing damage.

I think lightning protection should be at inverter PV input, not at the array.

 

[timselectric]

I think lightning protection should be at inverter PV input, not at the array.

I like both. But inverter is priority, if only one or the other.

 

[SniperX]

Built my own even though I have a 4 to 2 combiner from Ian at Watts247.

Vevor box and IMO disconnect, used chase nipples and Meyers hub between IMO and box, like this video:

You want a disconnect that is accessible, the Vevor is lockable and needs a "key" to open it.

View attachment 150181

Inside the box, just source some DIN rail, then breakers and surge protectors on the DIN.


View attachment 150182

I have been thinking about your post all night and this morning, I wondered if I could take an 8-2 combiner box I bought from Ian and split it? I did not know what I was buying at the time, and really only need three 4-2 (need two 4-2 for one charge controller and one 4-2 for a 2nd charge controller) but I bought 2 8-2's. Seems a waste to put that big box up and only use 2 strings in each one. Maybe I could buy the type of box you got, pull some of those fuses, etc. that won't be used out of the combiner boxes I have, and make new ones?

 

[NordicNerd]

This is a 16x16x6 Steel IP66 rated cabinet. I bought another to replace the one with the MC4's at the top that was inside, I had to re-engineer the entire setup when I got the 18K's. I stole the plate / breakers out of the original, and just mounted it in the new box. I bought DIN rail and put two rows down along with some 20A DIN bus connectors. The feed back to the Inverters will be into the bottom of the 2R2B bus blocks between the breaker and the surge protector. I'm really kind of pissed I got 2 white and 4 red surge protectors, I'm probably a little too anal about looks, but this is all #12 THHN stranded wiring. I could not get a ferule on the end, so it's just tucked in stranded.
You'll note 15A breakers. I'm kind of cautious about de-rating service. The panels are rated at 10.5ish amps, reality is they likely won't actually get that high even, so 15A is good for 12A continuous, and if something slowly creeps to danger I'd rather it just shut on down. This will also be my shutoff. Breakers are cheap, and fine as a switch if you are not turning it on/off very much.
In the lower pic you can see the box on the wall fed from the boxes on the roof. I also dropped a new ground rod, in the corner. My circa 70's house is apparently using the feed cable conduit pipe as groundt and while not awful, I prefer an 8' rod. Was not as hard to drive as I thought it was going to be. I'll tie the grounds together and keep the G/N bond in the main (150A) panel. Might drop another on the other side of the panel, haven't decided yet soil here seems pretty decent for ground unlike the NC sand hills I've grounded in the past. Any way will bring a ground up inside, and I still have to knock a 3/4 pipe thru the wall. Inverters are on the other side.

View attachment 154406


View attachment 154407

Nice set up. As a newbie, I have a question regarding the grounding in your combiner box. I see a grounding bus bar, but no grounding in or out of the box. so my questions are:
1. is this just a bonded system to the panel box?
2. Is there something I am not seeing where you run the ground to a plate/rod?

I suppose for the lightning arrestors in the box, you need a reference point which is the box?

Thanks all.

 

[Zwy]

I have been thinking about your post all night and this morning, I wondered if I could take an 8-2 combiner box I bought from Ian and split it? I did not know what I was buying at the time, and really only need three 4-2 (need two 4-2 for one charge controller and one 4-2 for a 2nd charge controller) but I bought 2 8-2's. Seems a waste to put that big box up and only use 2 strings in each one. Maybe I could buy the type of box you got, pull some of those fuses, etc. that won't be used out of the combiner boxes I have, and make new ones?

You could, won't bother anything. I've taken 4 to 1 combiners and made them into 4 separate strings in the box. I wanted the components and it was cheaper than sourcing items to build something.

 

[solarhombre]

Nice set up. As a newbie, I have a question regarding the grounding in your combiner box. I see a grounding bus bar, but no grounding in or out of the box. so my questions are:
1. is this just a bonded system to the panel box?
2. Is there something I am not seeing where you run the ground to a plate/rod?

I suppose for the lightning arrestors in the box, you need a reference point which is the box?

Thanks all.

He said he installed a new grounding rod because his house seems to be using the conduit as ground, and that he will tie both the main 150A panel ground and this new one so there's a single N-G bond. I assume he'll bring in one ground wire and connect it to the bus bar where all the SPDs and the box itself join.