Grounding Electrode System Requirements For PV System

[Eli1211]

I have read article 690.47. It is still unclear to me if the grounding electrode system part of my install is code compliant. My company does a lot of residential pv systems. The Solar GC mounts the panels on the roof, drops a line down to the inverter and then we take it from there. Where I am most installs go like this, from the inverter(s), to a A/C combiner panel, from the A/C combiner panel to a disconnect, from the disconnect to a dual meter socket enclosure that houses the pv meter and house meter w/one riser going up for the utility connection. These installs vary in their design at times, but you get the idea. We have always pounded two ground rods, hit the pv system service disconnect and called it a day as far as the GES is concerned for the A/C side of the installation. My team and I have passed many inspections this way. I have been told explicitly by at least a handful of inspectors that this is sufficient. I have one inspector at the moment requiring us to also bond to the homes GES, if they do not have one he is requiring us to install one, and bond to it. I would appreciate any clarity any of you can offer here. Is this one inspector correct and everyone else wrong, is everyone else correct and he is wrong or are we dealing with a gray area. Thanks everyone.

 

[ggunn]

I have read article 690.47. It is still unclear to me if the grounding electrode system part of my install is code compliant. My company does a lot of residential pv systems. The Solar GC mounts the panels on the roof, drops a line down to the inverter and then we take it from there. Where I am most installs go like this, from the inverter(s), to a A/C combiner panel, from the A/C combiner panel to a disconnect, from the disconnect to a dual meter socket enclosure that houses the pv meter and house meter w/one riser going up for the utility connection. These installs vary in their design at times, but you get the idea. We have always pounded two ground rods, hit the pv system service disconnect and called it a day as far as the GES is concerned for the A/C side of the installation. My team and I have passed many inspections this way. I have been told explicitly by at least a handful of inspectors that this is sufficient. I have one inspector at the moment requiring us to also bond to the homes GES, if they do not have one he is requiring us to install one, and bond to it. I would appreciate any clarity any of you can offer here. Is this one inspector correct and everyone else wrong, is everyone else correct and he is wrong or are we dealing with a gray area. Thanks everyone.

Grounding is by its very nature a gray area.

 

[rojay]

Without knowing what code cycle the AHJ is enforcing, I would say since the 2017 code cycle 690.47 was more clear in stating that the PV array equipment grounding conductors need to be connected to the grounding electrode system of the building supporting the array. The specifics of how this connection is to be made are definitely a gray area.

 

[Barney B]

What in Article 690 overrules the requirement in 250.58 for all of the separate services, feeders, and branch circuits supplying a building to be connected to the same grounding electrode(s)? I am not a solar guy, and I do not understand the issue here.

 

[wwhitney]

Is this one inspector correct and everyone else wrong,

Yes. The house can't have two different, disconnected GESs, one for the existing service, and one for the PV. So if you add ground rods, you have to tie them into the existing GES. But you also don't need to add ground rods, you can just use the existing GES.

 

[jaggedben]

Yes. The house can't have two different, disconnected GESs, one for the existing service, and one for the PV. So if you add ground rods, you have to tie them into the existing GES. But you also don't need to add ground rods, you can just use the existing GES.

In my experience solar will trigger the AHJ to make you upgrade the existing GES to current code if it does not already comply. So whether the existing GES is sufficient depends on its details. But with that caveat, you are entirely correct.

 

[Eli1211]

Thanks for the feedback everyone.

 

[Fred B]

My understanding is that, at one time it was more prevalent, there was an issue of DC side vs AC side grounding and interconnection between the 2 at the inverter, and bonding, seperate grounds etc. The newer equipment and codes seems to have gotten past some of that. 2017 was better, not sure of 2020, or what if any improvements will be in 2023.

 

[ggunn]

My understanding is that, at one time it was more prevalent, there was an issue of DC side vs AC side grounding and interconnection between the 2 at the inverter, and bonding, seperate grounds etc. The newer equipment and codes seems to have gotten past some of that. 2017 was better, not sure of 2020, or what if any improvements will be in 2023.

Part of the reason for that was transformer interfaced vs. transformerless inverters.

 

[pv_n00b]

Grounding is by its very nature a gray area.

I thought grounding is a green area, grounded is a grey area. Sorry, could not resist.

 

[pv_n00b]

My understanding is that, at one time it was more prevalent, there was an issue of DC side vs AC side grounding and interconnection between the 2 at the inverter, and bonding, seperate grounds etc. The newer equipment and codes seems to have gotten past some of that. 2017 was better, not sure of 2020, or what if any improvements will be in 2023.

DC array grounding all changed with the advent of non-isolated inverters. With ungrounded, sorry, "functionally grounded", PV arrays there is no call for a GEC from the DC ground to a grounding electrode system.