Sol-Ark 12K Parallel Stacking setup.

robby

Photon Vampire
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May 1, 2021
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1,593
In the attached, I updated the wiring diagram to include a bank of 6 EG4 batteries (48V, 100ah each) in parallel in the metal EG4 battery rack with the integrated busbars. Each EG4 has a 125A breaker built-in. I plan to run 4/0 wire connecting the busbars to the two parallel stacked Sol-Ark 12Ks (via multi-tap connectors). Each SA 12Ks has a 250A battery breaker.
Your setup is similar to mine except I only have one 12K unit.
Questions:

1) Is a DC disconnect required between the battery rack and the SAs? If so, what size disconnect and type (fuse vs. breaker) would you suggest? Any suggested brands/links would be appreciated.
I use a 250A breaker. I am cant remember the brand but I think it's the same as the Schneider DC breaker.
Link: 250A DC Breaker
2) Does the battery rack need a ground wire? The batteries are screwed into the rack, so I believe they would be considered grounded to the rack.
I would ground it.
Sol-Ark manual says to "install a subpanel for backup loads if you have Arc-Fault / GFI breakers, NOT a multi-circuit transfer switch. Can someone help me understand, why that is so? I do have AFCI breakers in the main breaker panel. Is that a problem if I keep the current design (see attached)?
Call Sol-Ark, I have not used an Arc-Fault breaker.
Are there any issues with the diagram that the permit office might take issue with?
Ask @FilterGuy or @Dzl they might be able to help you there.
 

Shimmy

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Feb 22, 2022
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Are there any issues with the diagram that the permit office might take issue with?
Curious if you had any issues; I know I am late to the party, but here is what I see:
  1. You do not show a DC grounding connection on the 48V negative bus. I think (but not certain) that is required.
  2. Your grid input feeds (tap conductors to disconnect) appear to be undersized; they would need to be #4 here (depending on length).
  3. Your inverter grid input disconnects should be fused or circuit breaker.
  4. Should state how many poles your PV DC disconnect is. I assume they are 4-pole.
  5. If your inverters do not have a built-in DC circuit breakers you would need external.
Where I live, you would need to show additional information, but that is a local issue.

The statement from SolArk about GFI is alluding to the fact that you could end up with circulating neutral current that would trip a main GFI-- typicall only an issue for 480V services 800A and up. GFI is to protect equipment, GFCI is to protect people-- two different things. AFCI doesn't matter in this situation.
 

A.J.

New Member
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Apr 2, 2021
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I updated the wiring diagram - see attached. I got the permit. I'm now in the slow process of DIY installation. Done installing the ground mount in the backyard about 150 feet away from the house. Next phase is to install the equipment on a 3/4" 4' x 8' plywood secured to the basement wall. Last phase will be digging an 18" deep trench between the house and the ground mount and run the 10 AWG wires for the 4 strings in 4 separate 3/4" pvc conduits to the 2 Sol-Arks via two 4-pole IMO 25 amp DC disconnect (each IMO handles 2 strings). The DC disconnects will be near the inverter on the basement wall. I'm not comfortable handling the wiring to the meter panel, so plan is have an electrician wire the AC portion of the project, before requesting AHJ inspection.

About your notes:
  1. You do not show a DC grounding connection on the 48V negative bus. I think (but not certain) that is required. See revised schematic attached.
  2. Your grid input feeds (tap conductors to disconnect) appear to be undersized; they would need to be #4 here (depending on length). 6 AWG wire is the max the Sol-Ark can accept on the AC side. But there is a manual transfer switch between the meter and the inverters. I'm using 4/0 SER wire between the meter and the transfer switch. Then 6 AWG wire between the transfer switch and the inverters.
  3. Your inverter grid input disconnects should be fused or circuit breaker. Using Square D 60 amp AC disconnect (breaker style) for inverter grid inputs ($18 each at Home Depot). Would prefer to use 63 amp AC disconnects (since each inverter can take up to 63 amps), but those seem to all be very expensive. Sure would like to know if there are any UL listed 63 amp AC disconnects under $100.
  4. Should state how many poles your PV DC disconnect is. I assume they are 4-pole. Yes, they're 4-pole and can receive 2 strings each.
  5. If your inverters do not have a built-in DC circuit breakers you would need external. They do - specs attached.
 

Attachments

  • Wiring Diagram Solar Ground Mount - R.pdf
    214 KB · Views: 11
  • 021 Sol-Ark 12K-P Inverter Specification Sheet.pdf
    263.9 KB · Views: 8

Biasjo

Renewable energy user - North Carolina
Joined
Dec 19, 2021
Messages
477
Good work. Let us know how this is coming along… I have a similar setup coming on a truck. Mine will be off-grid, backed with a 14kW gen, and inspection-less.
Only way to go. Mine runs as a permanent “backup” without all the inspections.

I’m not saying use Plastic wire nuts and make it “Good enough “ Just a lot easier without someone who doesn’t know the first thing about Solar making mandates to your system.
Our Local inspectors really do not know what to do with Solar.
 

onokai

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Apr 9, 2022
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Nor-Cal
I would use larger 1 inch or 1.5 inch conduit for easier pulls.(you can us the cheaper thinner ducting (DB duct) in 20 footers as long as its schedule 80 or 40 that comes up out of ground. I used 1.5 inch for an 80 foot run. I have the mouse and vac system to suck the string thru as well. Check on wire size with that long run on voltage drops as you will need to size up some.
I would also drop in a spare 3/4 inch conduit as i have to hand dig one in 1 year later when I added optimizers and needed a data cable run back to inverter area. Spare is always good.
 

Shimmy

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Feb 22, 2022
Messages
118
  1. You do not show a DC grounding connection on the 48V negative bus. I think (but not certain) that is required. See revised schematic attached.
  2. Your grid input feeds (tap conductors to disconnect) appear to be undersized; they would need to be #4 here (depending on length). 6 AWG wire is the max the Sol-Ark can accept on the AC side. But there is a manual transfer switch between the meter and the inverters. I'm using 4/0 SER wire between the meter and the transfer switch. Then 6 AWG wire between the transfer switch and the inverters.
  3. Your inverter grid input disconnects should be fused or circuit breaker. Using Square D 60 amp AC disconnect (breaker style) for inverter grid inputs ($18 each at Home Depot). Would prefer to use 63 amp AC disconnects (since each inverter can take up to 63 amps), but those seem to all be very expensive. Sure would like to know if there are any UL listed 63 amp AC disconnects under $100.
  4. Should state how many poles your PV DC disconnect is. I assume they are 4-pole. Yes, they're 4-pole and can receive 2 strings each.
  5. If your inverters do not have a built-in DC circuit breakers you would need external. They do - specs attached.
The Sol-Ark sheet you attached is a little short on technical information, but I don't see reference to a 48VDC disconnect internal to it. Personally I would want one disconnect for each inverter. If you are using two-pole disconnects then you don't need to ground the -48V bus, but that is outside my expertise.

The $18 disconnect you have is not fused; it is just an air conditioner disconnect. That would be a dangerous device to use on several levels-- first your wiring is only protected at 200A by the service disconnect, and second there can be exposed parts in it that are live. (I remember these being the "pull plug" style device, but maybe they are fancier now-- that was a few decades ago.)
 

onokai

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Nor-Cal
Sol Arc has a built in array power disconect on the side-newer version (mine is a almost 1.5 years old and is on bottom)
They out put (50 amp) is on a breaker on unit as well
I have two disconnects on my ground mount array one for each string before heading underground to sol arc.
In my case I'm going from the Sol Arc to a 100 amp subpanel (into a 50 amp breaker ) in a outbuilding which then goes a long ways back to my main 200 amp panel on house. It a bit awkward but does work well.
 
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RV10flyer

Solar Addict
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Mar 8, 2021
Messages
274
Sol-Ark instruction state not to ground 48V bat neg or pv neg circuits.

150' will give you approx 2.25% voltage drop.
 

waffles730

New Member
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May 20, 2021
Messages
3
run the 10 AWG wires for the 4 strings in 4 separate 3/4" pvc conduits
Hi, I see the question a few times in this thread about putting all PV conductors in the same conduit vs separate conduits but not much discussion on why do to it one way or the other. Why did you decide on 4 separate conduits? I am starting to plan a very similar project that is about a year out and will need to plan running conduit through the slab of a yet to be built addition, so I need to plan what is run through there. Thanks!
 

Shimmy

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Feb 22, 2022
Messages
118
Hi, I see the question a few times in this thread about putting all PV conductors in the same conduit vs separate conduits but not much discussion on why do to it one way or the other. Why did you decide on 4 separate conduits? I am starting to plan a very similar project that is about a year out and will need to plan running conduit through the slab of a yet to be built addition, so I need to plan what is run through there. Thanks!
Two conduits, one for each inverter, would have likely been a better choice, as would up-sizing the wire to #8 AWG to reduce voltage drop.

Electrical code is you need to de-rate when you get over 3 current carrying conductors in a conduit; 4-6 conductors you only get 80% of the ampacity and 7-8 you get 70%. However, pulling just two conductors in a conduit often results in more binding than 3 or 4, and if your wire sizing is dictated by voltage drop anyway you might as well reduce the number of conduits.
 
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