I had an issue with a EG4 inverter and tech support was an insistent that there was multiple ground neutral bonds in the system. Fully off grid system with no generator. It wasn’t the issue but it seems like these inverters are sensitive to it.
Is the inverter internally bonded, not that I’m aware of or what I’ve measured. And so I can’t figure out what it’s measuring between N/G to have a potential issue.
Maybe someone can explain?
Jay
Thanks all for your thoughts here. It seems that the general consensus so far is that the N-G should be bonded in the solar main disconnecting means when doing a supply side connection (even if it is not technically a separate service). When talking with Midnite Power, we made it very clear that we were talking about a N-G bond in the inverter combiner / solar main disconnect, and not the backed up loads panel. And being that NY is still on 2017 code (only going to 2020 next year), with the ambiguity in the code I am probably okay to undo the N-G connection in the main solar disconnect.
In this case specifically, we are backing up only a small subset of loads in the house. The reason for the two inverters is because there is about 24kw of solar. There is also a manual transfer switch to normally be able to power the loads off the inverters, but to be able to switch to powering the loads off the main panel in case of service needed on the inverters. The neutrals in this system are all connected together, and I am not sure if that could cause issues. It is probably difficult to explain all the details in words, so I am copying part of the three line diagram here. The second picture is the conductor and conduit schedule.
Tom, I get it that the error sounds like it is on the DC side based on the words, but when I talked to Midnite about it they were pretty clear about it being due to multiple N-G bonds and they did not mention that it could have anything to do with the DC side.
Jason, that is a good idea as well to check the loads that got moved over to see if there are any other inadvertent N-G bonds on the premises. This also similar to what Midnite suggested, which was to lift the N-G bond in the main panel and then see if they are still bonded somewhere else. It seems like it can be a slow process to track that down with power cut to the house, but that might be what I have to try if removing the N-G bond in the solar main disconnect does not help.
So, my main questions to anyone who has an opinion here are two fold: 1. Do you bond the N-G in general in the main solar disconnect for a supply side connection? 2. Specifically with the Midnite AIO inverters, has anyone else had issues with this "CA-DC link Overvoltage error" due to having a second N-G bond in the house? (one in the main service panel, and one in the solar main disconnect if it is a supply side connection). Or have you seen this error and found that it was caused by something else?
Cheers, Dave
On Thu, Oct 23, 2025 at 5:25 PM Jason Szumlanski via RE-wrenches < [email protected]> wrote: I agree. It is not a separate service. It is a "tap" of the existing service (I use that term loosely here). The additional service disconnect for the supply side interconnection should have L1, L2, and N connected ahead of the premises main disconnect with no EGC. There should be a N-G bonding jumper in the PV service disconnect. Then there should be no N-G bonds downstream of both the premises main disconnect and the PV service disconnect.
Basically, it's the same as two main disconnects running from a meter enclosure. Each of the service disconnects has a N-G bond required.
Some AHJs (the crazy ones) require an EGC between the enclosure where the supply side connection is made and the PV service disconnect. This creates a parallel fault path, and should not be allowed, in my humble opinion.
Now it sounds like you might be doing a partial home backup. The issue there is that sometimes the loads or enclosures you moved over the backup load panel have inadvertent N-G bonds. Sometimes it's as simple as someone who got creative and used a ground as a neutral in a switch box. I say simple, but that can be hard to track down. When Midnite said to remove it from the inverter distribution panel, they were probably talking about the protected loads panel.
I think more information is needed.
Jason Szumlanski Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956 Florida Certified Electrical Contractor EC13013208 On Thu, Oct 23, 2025 at 11:03 AM Tyrone Houck via RE-wrenches < [email protected]> wrote: My interpretation, and the way it was explained to me by both Ryan Mayfield and Kyle Bolger(several years ago at this point, popular opinion may have changed since). Is that it is not a seperate service. It is however required to have a ground-neutral bond( though in my opinion pointless and redundant as there is a bond in the enclosure where the tap is made). If it gives you any issue, ensure as close to equal potential to the grounding electrode as possible(and make sure your neutral is appropriately sized). I personally don't see the point but it is an NEC requirement
On Thu, Oct 23, 2025, 6:08 AM Dave Tedeyan via RE-wrenches < [email protected]> wrote: Hi All,
For years I have understood that when doing a supply side connection, you are supposed to bond the neutral to ground in the solar service disconnect. I have a Midnite AIO system with two inverters (set up as a supply side connection) that recently was getting a CA-DC link Overvoltage error. When talking to Midnite, their first response was to make sure that there was only one N-G bond in the whole system. When I mentioned that the solar is a separate service and thus there is a N-G bond in both the main panel and the inverter distribution panel, they said to remove it from the inverter distribution panel. I want to make the system work right, but I also am hesitant to do something against how I have understood the NEC to be for a long time. I am curious if you all have thoughts on this or run into a similar situation.
Cheers, Dave
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