Sol-Ark 12K Parallel Stacking setup.

A.J.

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Apr 2, 2021
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Hello, I've been reading discussions on this forum for a while, but this is my first time posting here. I'm planning a ground mount 16.2kW system:
  1. 36 450W Bifacial Znshinesolar panels (4 strings of 9 panels in series) - specs attached
  2. 2 Sol-Ark 12Ks parallel stacked (as shown in the attached wire diagram from the 12K Manual)
  3. Manual Bypass Transfer Switch - Siemens General Duty Double Throw 200 Amp 240-Volt 2-Pole Non-Fusible Safety Switch
  4. ReadyRack ground mount racking with ground screw foundation
  5. Ground mount about 150' west of the house.
  6. PV wire, direct burial rated in 3/4" Schedule 80 PVC conduit with 2 current carrying 10 AWG conductors + 1 ground conductor (6 AWG bare copper or will 10 AWG do?) in each conduit. Thinking one conduit per string. Can all DC wires and ground conductors be in one large (2") conduit? Does each string need its own ground conductor going back to the house, or will one ground conductor bonded to all the panel frames and racking do?
  7. 150' long trench 18" deep
  8. 2 IMO 25A DC disconnects (each IMO can handle two incoming DC strings)
  9. 4 Square D QO200TR 60A AC disconnects for the 2 outputs of the Sol-Ark 63A Grid and Load breakers (x2)
  10. 1 Square D D324NRB 200A Fused Disconnect. Instead, should I use a 200A knife blade disconnect with two 60A breakers to feed the Sol-Ark like an electrician friend suggested?
  11. 30kW EG4 battery bank but it is not UL listed, so initially this will be just grid-tied w/o battery backup.
Before I apply for the permit, I'm hoping the collective intelligence/wisdom on this forum can help me with some of the questions above. My AHJ wants a single line wire diagram so attached is my take at boiling down the Sol-Ark Wire Diagram to my project. I'd appreciate your thoughts on whether this will even fly with the AHJ.

Thank you in advance for your advice and guidance.
 

Attachments

  • Sol-Ark 12K Parallel Stacking Wire Diagram.pdf
    664.6 KB · Views: 104
  • 450 Watt Bifacial Datasheet Znshine.pdf
    8.5 MB · Views: 40
  • Solar Ground Mount Schematic & Layout.pdf
    129.4 KB · Views: 53

FilterGuy

What, me worry?
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Can all DC wires and ground conductors be in one large (2") conduit? Does each string need its own ground conductor going back to the house, or will one ground conductor bonded to all the panel frames and racking do?
One conduit should be sufficient, but there will be 4 current carrying conductors so the wires will have to be over-sized to account for the derating.
(it may turn out they have to be over-sized for voltage drop anyway).


One Equipment Grounding conductor should be sufficient. However, if the equipment grounding conductor goes back to your house, it will effectively create a 2nd earth grounding point (one at the house and one at the ground mount). If the code/inspector will let you get away with it I would not run the Equipment grounding conductor to the house. Instead, I would ground the frames to the racking system and make sure the racking system is properly tied to earth ground.

If the code (or inspector) requires the frames to be tied to the house grounding system, I would take the conductor directly to the Grounding electrode of the house. (The line diagram shows it going into the breaker box. This is OK, but I would rather see it go to the grounding electrode if possible). This will help prevent any issues that could be caused by large voltage differentials between the two separate earth ground points.
 

A.J.

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Apr 2, 2021
Messages
9
Thank you, FilterGuy. Originally, I was planning to have a driven 8' ground rod at the ground mount rack, but then I read that it would cause voltage differentials between it and the house ground rod, thus the current design to not have a ground rod at the ground mount. If it were up to me, I'd ground the frames to the racking system and make sure the racking system is properly tied to earth ground. That would eliminate running grounding conductors back to the house. I just don't know if that aligns with the NEC though.
 

FilterGuy

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Thank you, FilterGuy. Originally, I was planning to have a driven 8' ground rod at the ground mount rack, but then I read that it would cause voltage differentials between it and the house ground rod, thus the current design to not have a ground rod at the ground mount. If it were up to me, I'd ground the frames to the racking system and make sure the racking system is properly tied to earth ground. That would eliminate running grounding conductors back to the house.
Yes, you should definitely avoid tieing the grounding system to two separate earth grounds. However, ground mount systems make this difficult. The metal rack and 'screw anchors' will create a connection between the earth ground and the panel frames (even if it is not a good connection, it is still going to be there). That means that if you bring a frame ground wire back to the house and tie it into the grounding system, there will be two separate earth grounds on the same grounding system. That is why I prefer to properly ground the mounting rack and let it be the only ground to the panel frames. This keeps the two earth-ground points separate. However, I have heard of cases where the code inspectors require the ground mount frames be tied to the house ground and cases where the inspector does not require it.

If you do have to bring a wire back to the house tie it to the grounding system as close to the grounding electrode(s) as possible.

I just don't know if that aligns with the NEC though.
The grounding requirements in the NEC are complicated to begin with. They get more confusing with solar. Ground-mount solar is the most confusing because it brings in the specter of a 'separate structure'. I have slogged through the NEC a couple of times and have never convinced myself that I understand the exact requirements for this particular case. Normally I would just go by what inspectors say but because it is so confusing, you never know how a particular jurisdiction or even a particular inspector will interpret the requirements. At the end of the day, it is the inspectors that determine what you have to do.... not the NEC. If you have a good relationship with the local inspectors, you can ask them what they will require.
 

FilterGuy

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I have slogged through the NEC a couple of times and have never convinced myself that I understand the exact requirements for this particular case.
Just to be [un]clear: There used to be a requirement to tie the frames to a grounding electrode at the ground mount *and* tie it back to the grounding system in the house (This was a bad requirement). However, I *think* this has changed and gives the designer some options:
1) It is still allowed to bring the ground wire back to the house. When the ground wire is connected back to the house, it is allowed but not required to have a grounding electrode at the panel mount.
2) I *think* (But not 100% sure) it is also allowed to properly ground the mounting rack and not bring the ground wire back to the house. (This is my preferred solution because it keeps the two separate earth ground points separated.)

BTW: This brings up a couple of other reasons for so much confusion.
- The requirements have been changing in each release of the code so just as you think you have it figured out.... it changes.
- When there are options in the code, some people read one method as 'the' requirement and other people read the other method as 'the requirement'
 

Gubbool

Sol-Ark & HAB’s
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Montana
Hello, I've been reading discussions on this forum for a while, but this is my first time posting here. I'm planning a ground mount …
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.
 

SolarPrep

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I second the recommendations by FilterGuy. With the distance involved, I'd want to ground that racking where it is installed. I'm looking at a smaller version of your project (about half sized) and the same issue is coming up. By an interesting coincidence, the utility is burying all the lines near us, and has a really good program for updating meter assemblies, so I hope to take advantage of that opportunity to make changes.

I'd bury a bigger pipe than 3/4 just for future-proofing. Just out of curiosity, why schedule 80? Is that required?

Nice project. Good luck!
 

robby

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I would ask Sol-Ark about those 9 Panels in Series. Your pushing 445V which is really close to the upper limit of the MPPT at 450. If I was spending this kind of money I would definetly make sure the system has battery Backup from the start. I like the EG4 but to pass inspection your better off going with the Fortress eVault Max with only 18.5KWh of power. It will cost the same as the 30KWh of EG4s but you will now have a fully certified Grid tied system with Backup.
 

ArthurEld

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  1. 30kW EG4 battery bank but it is not UL listed, so initially this will be just grid-tied w/o battery backup.
Before I apply for the permit, I'm hoping the collective intelligence/wisdom on this forum can help me with some of the questions above. My AHJ wants a single line wire diagram so attached is my take at boiling down the Sol-Ark Wire Diagram to my project. I'd appreciate your thoughts on whether this will even fly with the AHJ.

Thank you in advance for your advice and guidance.
I started with 100Ah of UL listed AMG for my Sol-Ark 12K. It won't last very long but it allows me to use my Solar when the sun is shining and it gives me some uninterruptible power.
My 1000Ah of non UL LFP will only be used if the grid goes down for a long time.
 

FilterGuy

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Your pushing 445V which is really close to the upper limit of the MPPT at 450.
Definitely need to account for cold temp voltage rise..... unless the panels will never be below 25degC

 

SolarPrep

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I would ask Sol-Ark about those 9 Panels in Series. Your pushing 445V which is really close to the upper limit of the MPPT at 450. If I was spending this kind of money I would definetly make sure the system has battery Backup from the start. I like the EG4 but to pass inspection your better off going with the Fortress eVault Max with only 18.5KWh of power. It will cost the same as the 30KWh of EG4s but you will now have a fully certified Grid tied system with Backup.
robby: i was reading the 2020 NEC, and it does not appear that batteries fall under the UL requirement. I then read on the UL site, and of course they can certify batteries, but that is at the discretion of the manufacturer. Then contacted the State Fire Marshall and lead inspector for solar. They told me they only look at UL for batteries if the project specifically calls for it. I had also read a document that stated that the UL process for testing inverters did not cover the battery charging portion of the inverters.

All of this seems to fly in the face of assumptions. And many of those are flying around too. Our AHJ is not clear as to this issue, but numerous installers have told me they have never been questioned about the batteries. Maybe because there still is not a lot of them being installed, at least around here. But, if applying for a grid tie arrangement, our local utility would likely require UL. There is a specific line item on the application asking about whether or not batteries will be involved. There could be many explanations for why.

You comment does have merit, and I'd agree that the Fortress battery could be a better choice.

I wish they would standardize this kind of thing.
 

robby

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robby: i was reading the 2020 NEC, and it does not appear that batteries fall under the UL requirement. I then read on the UL site, and of course they can certify batteries, but that is at the discretion of the manufacturer. Then contacted the State Fire Marshall and lead inspector for solar. They told me they only look at UL for batteries if the project specifically calls for it. I had also read a document that stated that the UL process for testing inverters did not cover the battery charging portion of the inverters.

All of this seems to fly in the face of assumptions. And many of those are flying around too. Our AHJ is not clear as to this issue, but numerous installers have told me they have never been questioned about the batteries. Maybe because there still is not a lot of them being installed, at least around here. But, if applying for a grid tie arrangement, our local utility would likely require UL. There is a specific line item on the application asking about whether or not batteries will be involved. There could be many explanations for why.

You comment does have merit, and I'd agree that the Fortress battery could be a better choice.

I wish they would standardize this kind of thing.
That does sound very confusing.
I suspect that they are still in a transition mode from Lead Acid and AGM batteries which would not be an issue. I think this is all going to be standardized very soon because of the LG fires and Teslas power walls ability to cause really big fires. If you can't get something definitive in writing I would play it safe. That's is a lot of money to spend on batteries only to hear it cannot pass inspection.

The other option is to just get a single eFlex or some other cheaper UL certified battery and then get your system certified.
 
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robby

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I started with 100Ah of UL listed AMG for my Sol-Ark 12K. It won't last very long but it allows me to use my Solar when the sun is shining and it gives me some uninterruptible power.
My 1000Ah of non UL LFP will only be used if the grid goes down for a long time.

1000Ah :p OMG.
Are they on a separate circuit and you have to manually switch over to them?
What is the SOC that you leave them at? Why not use them all at once on the Sol-Ark?
 

ArthurEld

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1000Ah :p OMG.
Four 280Ah 48V batteries
Are they on a separate circuit and you have to manually switch over to them?
I disconnect the AMGs then connect the LFP
What is the SOC that you leave them at? Why not use them all at once on the Sol-Ark?
I charge them to 3.4V during hurricane season. otherwise I leave them at 3.3V
There is no reason to keep them connected. And they will last forever disconnected.
 

robby

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Four 280Ah 48V batteries

I disconnect the AMGs then connect the LFP

I charge them to 3.4V during hurricane season. otherwise I leave them at 3.3V
There is no reason to keep them connected. And they will last forever disconnected.
Oh I thought when you said non UL LFP that you meant some DIY or Lower priced batteries like the Gyll. That was why I was worried about the SOC, I was wondering if you were leaving LFP batteries at 100% permanently.
Now I get the picture. Yeah those AGM batteries will have no problems being left on standby.
 

A.J.

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Apr 2, 2021
Messages
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I second the recommendations by FilterGuy. With the distance involved, I'd want to ground that racking where it is installed. I'm looking at a smaller version of your project (about half sized) and the same issue is coming up. By an interesting coincidence, the utility is burying all the lines near us, and has a really good program for updating meter assemblies, so I hope to take advantage of that opportunity to make changes.

I'd bury a bigger pipe than 3/4 just for future-proofing. Just out of curiosity, why schedule 80? Is that required?

Nice project. Good luck!
I meant to say Schedule 40 PVC, not Schedule 80. It would be easier and cheaper to run all 8 current carrying 10 AWG PV wires (plus a ground wire if AHJ requires it) in one 1.5" PVC conduit versus running 4 separate 3/4" PVC conduits with a pair of 10 AWG PV wires. I have 4 strings. Any issues running all the DC wires in one 1.5" conduit?
 

A.J.

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Apr 2, 2021
Messages
9
I would ask Sol-Ark about those 9 Panels in Series. Your pushing 445V which is really close to the upper limit of the MPPT at 450. If I was spending this kind of money I would definetly make sure the system has battery Backup from the start. I like the EG4 but to pass inspection your better off going with the Fortress eVault Max with only 18.5KWh of power. It will cost the same as the 30KWh of EG4s but you will now have a fully certified Grid tied system with Backup.
Yes, I talked to Sol-Ark about the panel BSTC specs and they ran it through their calculator at the worst case temps for my zip code (22405) and it passed. Granted, at worst case it was cutting it a bit close, but it still was within their MPPT specs. I wonder if there is a voltage-limiter device that could be used to cap the voltage...

I will think about getting a UL listed battery bank.
 

robby

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Yes, I talked to Sol-Ark about the panel BSTC specs and they ran it through their calculator at the worst case temps for my zip code (22405) and it passed. Granted, at worst case it was cutting it a bit close, but it still was within their MPPT specs. I wonder if there is a voltage-limiter device that could be used to cap the voltage...

I will think about getting a UL listed battery bank.
If they say it's fine then I would go with it. The only thing I would do is have the conversation again via email so you have proof. When I was thinking of using SMA I had some very positive phone conversations with one of their sales people about doing a Micro Grid and got a verbal list of what equipment would be needed.
I actually purchased an Inverter and was on my way to getting a Sunny Island when I revisited the subject again with him Via email and asked for the list again in writing. He said he was not certain about it and would have to get back to me.
I ended up having to get back to him and then two days later he wrote me back stating that I could not do it without adding more equipment than he had stated before. I ended up returning the Sunny Boy and went with the Sol-Ark.
 

medfly101

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Dec 12, 2021
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I have a 12k solark and it works fine but i should of just went with 2 of them off the get go. I have my array running around 460 vdc to 490vdc, 2 strings of 11 qcell 420w panels in series. Im in Pittsburgh, Pa so its not a solar paradise. If you know where to get a voltage limiter, let me know. I looked and could not find what i was looking for.. I would love to be able to oversize my array alittle more and not worry. BTW the solark warns you at 520vdc w/ an alarm. 550vdc is limit.
 

A.J.

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Apr 2, 2021
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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.

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.
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.

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)?

Are there any issues with the diagram that the permit office might take issue with?
 

Attachments

  • Wiring Diagram 16kW Parallel Stack + 30kW Battery Bank_R.pdf
    214 KB · Views: 32
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