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Neutral and Ground bars in Panel for Off-Grid Sol-Ark System

DIYSolarShed

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Hello all,

I am nearly complete in my install of a Sol-Ark 12K + solar panels + a Fortress 18.5 battery.

I had a local electrician here helping with the install, but there was one question that he was not 100% certain about (and I don't want to just guess... ).

Basically, what is the correct configuration for the off-grid load center in terms of a combined vs split neutral and ground bar inside the load center? This is a Square D QO 100A panel: https://www.homedepot.com/p/Square-...-Center-with-Cover-Door-QO816L100DS/100170999

Youtube says to split neutral and ground in a subpanel, but this is not really a subpanel (unless the Sol-Ark is considered the "main" panel??).

Just to confirm, there is zero grid tie, zero utility meter on this setup. The ground is being accomplished with an 8ft copper-clad rod.

Thanks in advance!
 
Just talked to Sol-Ark. They suggested linking neutral and ground *inside* the Sol-Ark and keeping them separate in the load center (mainly for aesthetics/flexibility).

Does that sound right to everyone here?
 
Just talked to Sol-Ark. They suggested linking neutral and ground *inside* the Sol-Ark and keeping them separate in the load center (mainly for aesthetics/flexibility).

Does that sound right to everyone here?
Just got done installing my Sol-Ark. Sounds like you are on the right track.

Essentially if you are off the grid, the sol-ark is a separately derived system, which means the neutral is essentially created inside of the unit. The two live conductors and neutrals are essentially like a bird on a power line. They may be live, but since they don't connect to the ground, a ground fault would just make the ground live.

In the event of a ground fault, we must pass sufficient current back to the source (Neutral), in order to trip the breaker.

Without the neutral-ground bond, there is no path back to the source (Neutral).

If you are in a home that already has electrical service, the utility company / builder has already installed this neutral-ground bond, so in this case you would run seperate neutral & ground wires to the sol-ark and utilize the existing bond, there can only be one neutral-ground bond..

Since you are starting from scratch, essentially, you need to create this neutral-ground bond. There can only be one of these in a system. I repeat this but go into the why shortly. Sol-ark appears to be suggesting that this bond be in the inverter, but it in theory could be in the load center, so long as the loadcenter is rated as "Service Equipment". The load center in the link is not rated as such, but this is OK.

By bonding the neutral and earth in your sol-ark, you essentially are making the sol-ark the "service equipment" because it has the main bonding jumper and service disconnecting means, and is rated as such.

Your service disconnect, or as it might be easier to understand, "Main Breaker" is the "Load" breaker inside of the sol-ark. Now so long as your load center is within 50 feet or line of sight, the disconnecting means of your load center (Panel) is the "Load" breaker in the sol-ark. You do not need a main breaker in your load center because of this.

Explaining more on the "Only one Neutral-ground bond":

Let's imagine a system that for some reason had a neutral-ground bond in both the sol-ark and in the load center. Now there is the potential for both the green grounding conductor and the white grounded conductor to carry not only fault current, but also your regular neutral loads. Let's say for some reason, an electrician needs to work on the system live. For some reason if they broke the green wire between the loadcenter and the sol-ark, there is a chance that those exposed metal parts become live, because they were previously used to carry neutral current. This would be a huge safety issue.
 
I would bond neutral and ground at this "main" load center, probably a green screw through the neutral bar to enclosure. Ground rod and all other grounds would go there.

That way, if inverter is swapped, or generator connected instead, ground is still there.

That's a small panel. I would have used at least a 125A, 12 space 24 circuit.
I have two 8-space, one 6-space, just for oddball stuff. I had to put dual breakers in the 6 space so I could fit a 50A breaker for my welder.
One of the others came as as generator transfer switch, and I replaced the 100A an 30A in it with 70A and 70A, use it so my house either goes to the inverter or to main panel fed by grid.
 
I would bond neutral and ground at this "main" load center, probably a green screw through the neutral bar to enclosure. Ground rod and all other grounds would go there.

That way, if inverter is swapped, or generator connected instead, ground is still there.

That's a small panel. I would have used at least a 125A, 12 space 24 circuit.
I have two 8-space, one 6-space, just for oddball stuff. I had to put dual breakers in the 6 space so I could fit a 50A breaker for my welder.
One of the others came as as generator transfer switch, and I replaced the 100A an 30A in it with 70A and 70A, use it so my house either goes to the inverter or to main panel fed by grid.
The load center he linked to is NOT rated as service equipment, therefore cannot house the neutral-ground bond.

I agree the loadcenter should be a bit bigger, but he didn't explain his loads and what he is trying to power, so we can't assume it's like my setup where we currently have 5 RV's plugged in and a shop with welders, grinders, saws and a drill press. It might just be to power a couple of lights.
 
This is only powering four circuits, and will “never” be expanded. 1x circuit for for a de-rated EV car charger, and 3x circuits for my garage/shop/freezer. That’s why I got the fairly small load center.

I am fine bonding inside the Sol-Ark, unless there is a major reason to avoid that?

Thanks again for the replies!
 
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The load center he linked to is NOT rated as service equipment, therefore cannot house the neutral-ground bond.

I agree the loadcenter should be a bit bigger, but he didn't explain his loads and what he is trying to power, so we can't assume it's like my setup where we currently have 5 RV's plugged in and a shop with welders, grinders, saws and a drill press. It might just be to power a couple of lights.


Perhaps because it is only rated 10kA short circuit current?

Ground bar is an optional accessory. Can't tell from documents if a ground bonding screw (and corresponding hole in enclosure) is provided.
Ignoring "rated", I don't see any actual physics/engineering/safety issue with the ground bond occurring in the box, with power source being an inverter or generator.

Bonding externally such as at the inverter, just means a fault current goes by ground wire back to the inverter where it joins neutral, rather than going to neutral in this box and then following the (larger) neutral wire back to inverter.

I am fine bonding inside the Sol-Ark, unless there is a major reason to avoid that?

No major reason. I just question everything, especially "Authorities" (although maybe not to their face if they are the ones "Having Jurisdiction")
 
Actually, what are you guys seeing on the original load center I posted where it is “not” rated for service? Is that because it doesn’t have a separate shutoff position for a main breaker?
 
Is that because it doesn’t have a separate shutoff position for a main breaker?
yes. The "main" breaker would be found at the service panel that is supplying that sub panel. That is also the pannel I installed for my "critical loads"

inverters1.jpg


That was in process, I was working on getting all the wireing moved over to the sub panel and had it powered by the same brakers that I would eventually use to power the inverters.
 
I haven't found a statement either that it is or isn't rated.

It has no main breaker. But it could be backfed.
The generator switch I bought, based on the 3R version of that box, had a 100A and a 30A breaker (interlocked) which were secured against popping off.
Most branch circuit breakers are rated 10kA interrupting, vs. 22kA for main breaker. I do have some branch-style breakers intended for service connection and rated 22kA (a 100A, 3-pole breaker)

Just for my learning, is this load center rated for the neutral bond?


That one is. But I can't find where it says so.

No main breaker is a normal thing. Sometimes one box has service entrance, meter, main breaker. Then the load panel has no breaker. But maybe in that case it would be normal to tie neutral and ground together in the box with main breaker.

My place is wired that way, convenient for something like a "line side tap" for PV but without limits on size. I have a 200A "main" breaker in the panel in addition to a 200A "main" at the meter, so I can connect another 100A or 200A tap between them, not limited to 40A like a true line-side tap between meter and main.
 
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