Sub Panel Looses Ground when PV is ON

[TechnoKing]

Hi All! First time post on the forum, but long time lurker. I learned quite a bit from this forum while building my system.
I am doing safety checks on my system before i move critical loads to my sub panel. I am having an issue where my sub panel looses its ground under the following conditions:

- When I kill my AC breaker that sends AC IN to my EG4 3000EVH-48 (simulating a power outage?)
- When I turn ON my DC isolator for my PV array

Signature solar instructed me to fix this issue by sending the EG4s ground to my main ground that runs into my panel. I tested this yesterday and it did not help (I didnt think it would).

I have detailed this issue with a video here on Reddit:
Video Of Issue

Here is all the specs & pics on my build including images with the front covers off:
Specs, Pics, and Info

Note: There is an error in my diagram, my battery is 48v NOT 24v. There are 0 errors on inverter

If any more info is needed please let me know! This is my final check before I move my Lab and my critical loads (water pump + filtration system) to my sub panel

 

[SignatureSolarJess]

Hi All! First time post on the forum, but long time lurker. I learned quite a bit from this forum while building my system.
I am doing safety checks on my system before i move critical loads to my sub panel. I am having an issue where my sub panel looses its ground under the following conditions:

- When I kill my AC breaker that sends AC IN to my EG4 3000EVH-48 (simulating a power outage?)
- When I turn ON my DC isolator for my PV array

Signature solar instructed me to fix this issue by sending the EG4s ground to my main ground that runs into my panel. I tested this yesterday and it did not help (I didnt think it would).

I have detailed this issue with a video here on Reddit:
Video Of Issue

Here is all the specs & pics on my build including images with the front covers off:
Specs, Pics, and Info

Note: There is an error in my diagram, my battery is 48v NOT 24v. There are 0 errors on inverter

If any more info is needed please let me know! This is my final check before I move my Lab and my critical loads (water pump + filtration system) to my sub panel

Hi @TechnoKing I have our tech team working on this again as we speak. If you'd like to email me at engagement@signaturesolar.com with your full name, I'd love to get you back in touch with our team to get this sorted today.

 

[pvgirl]

How are you determining loss of ground? What are we talking about as ground, the equipment grounding conductor, or the grounded conductor aka neutral?

EDIT: I can't tell from the pics how is the ground from the subpanel connected to the houses ground system?

 

[TechnoKing]

How are you determining loss of ground? What are we talking about as ground, the equipment grounding conductor, or the grounded conductor aka neutral?

EDIT: I can't tell from the pics how is the ground from the subpanel connected to the houses ground system?

Thanks for the Reply! Here are my responses that may help:
- I am determining loss of ground by the grounding light on the power strip being illuminated when PV is OFF and OFF when PV is ON

- The sub panel is grounded to my main panel's grounding bar. This is done via the AC IN coming from my 30A breaker. The video i took shows how this is wired up as i have the face plate off my main panel.

 

[TechnoKing]

Hi @TechnoKing I have our tech team working on this again as we speak. If you'd like to email me at engagement@signaturesolar.com with your full name, I'd love to get you back in touch with our team to get this sorted today.

I have been working with Tristan on this issue. I dont have a ticket number but I did ping him with a link to this post and another updated video last evening.

 

[SignatureSolarJess]

I have been working with Tristan on this issue. I dont have a ticket number but I did ping him with a link to this post and another updated video last evening.

Understood. I'd like to get a couple of other techs to help out and get this sorted for you. If you'd like to reach out, I can pull that ticket number with your name, email or phone number.

 

[ChrisG]

How are you determining loss of ground? What are we talking about as ground, the equipment grounding conductor, or the grounded conductor aka neutral?

EDIT: I can't tell from the pics how is the ground from the subpanel connected to the houses ground system?

based on the pics, I think, it looks like he’s using the inverter to pass through ground. See a green wire on AC IN and a green to the lug on the bottom of inverter going to AC out wires into sub panel. Maybe when he’s in inverting mode the neutral is not bonded to G.

 

[pvgirl]

This seems to be a common issue with these inverters: https://diysolarforum.com/threads/eg4-3000ehv-neutral-bond-grounding.51544/

I would measure the voltage between neutral and ground when the PV is on, it should be close to zero, if it is not there is an issue with inverter not passing thru the neutral when on PV.

 

[TechnoKing]

This seems to be a common issue with these inverters: https://diysolarforum.com/threads/eg4-3000ehv-neutral-bond-grounding.51544/

I would measure the voltage between neutral and ground when the PV is on, it should be close to zero, if it is not there is an issue with inverter not passing thru the neutral when on PV.

This was great advice! I did the test you requested and found a very interesting thing while doing so:
- Under PV my inverter hums a bit. When i put my voltmeter between the ground and neutral when PV was ON the humming went away AND the ground light flipped on my power strip coming from the sub panel! As soon as i took the voltmeter off, the humming came back and the ground light fell off.

Isn't this technically making a downstream ground neutral bond and a big no no?

Voltage between ground and the neutral was 0 when the PV was ON
Voltage between the ground and neutral was 81 (weird number) when the PV was OFF

Also it should be mentioned this inverter has updated firmware and was shipped Q1 of this year. This should have the fixes in place to fix the ground neutral bond issue.

 

[TechnoKing]

based on the pics, I think, it looks like he’s using the inverter to pass through ground. See a green wire on AC IN and a green to the lug on the bottom of inverter going to AC out wires into sub panel. Maybe when he’s in inverting mode the neutral is not bonded to G.

This looks like my issue. If you see the comment below my grounding light comes on on my power strip once i manually bridge the neutral on the AC out with the ground on the AC in