Interconnected power production pv disconnect neutral size bonding

[Jpflex]

When getting into pv solar systems, apparently the service grounded conductor neutral is jumped from either the grounded conductor buss at the service panel or the neutral lug at the main meter to bond the pv system disconnect?

How do you size this grounded jumper conductor terminating and bonding to the pv system disconnect?

Is this smaller neutral jumper sized to the largest conductors from ac /dc converter terminating to the supply back feed breaker on the load side of service panel buss? Or based the size per the largest ungrounded conductors supplying the service 250.102c?

Where can I find this in code? Thanks

 

[don_resqcapt19]

What code cycle applies to your installation?

 

[jaggedben]

When getting into pv solar systems, apparently the service grounded conductor neutral is jumped from either the grounded conductor buss at the service panel or the neutral lug at the main meter to bond the pv system disconnect?

For a load side connection that's incorrect; you bond the disco with an EGC.
For a supply side connection it's best to think of it as being the same as a separate service disconnect. So, something like what you say, but just bring the neutral to the disco with the other conductors like normal.

You may find some old discussion or out-of-date/rouge AHJs who don't see PV systems this way but the code has mostly settled around this since 2020.

How do you size this grounded jumper conductor terminating and bonding to the pv system disconnect?

For a supply side connection: Per the circuit current requirement or table 250.102, whichever is larger. With grid-tied PV systems (without backup loads) that's likely to be Table 250.102.

Is this smaller neutral jumper sized to the largest conductors from ac /dc converter terminating to the supply back feed breaker on the load side of service panel buss? Or based the size per the largest ungrounded conductors supplying the service 250.102c?

The latter. The purpose is the same as with any other service disconnect; to carry fault current back to the utility and trip a breaker. Forget that energy from the PV system may be flowing back to the utility, that's power limited. The major safety issue is still fault current from the utility.

Where can I find this in code? Thanks

250.24(C) and/or 250.25. And 705.11, sort of. Again that's all for supply side connections. For load side interconnections none of this applies.

 

[Jpflex]

What code cycle applies to your installation?

This was the exact instructions from a video from Mike holt. I will have to find the video and snap a picture. I’m using the 2023 NEC handbook

 

[Jpflex]

What code cycle applies to your installation?

I forgot to mention that this is not a question for a project I am currently on. Instead, I am reviewing NEC articles covering PV systems and interconnected power production sources because I will be starting a new job on Monday.

My former occupation as an industrial electrician at a mine site closed down due to loss of investor funds. Instead of working with huge 3 phase motors and crushers I will now be working on large 1,500 volt DC inverters.

 

[Jpflex]

For a load side connection that's incorrect; you bond the disco with an EGC.
For a supply side connection it's best to think of it as being the same as a separate service disconnect. So, something like what you say, but just bring the neutral to the disco with the other conductors like normal.

You may find some old discussion or out-of-date/rouge AHJs who don't see PV systems this way but the code has mostly settled around this since 2020.


For a supply side connection: Per the circuit current requirement or table 250.102, whichever is larger. With grid-tied PV systems (without backup loads) that's likely to be Table 250.102.


The latter. The purpose is the same as with any other service disconnect; to carry fault current back to the utility and trip a breaker. Forget that energy from the PV system may be flowing back to the utility, that's power limited. The major safety issue is still fault current from the utility.


250.24(C) and/or 250.25. And 705.11, sort of. Again that's all for supply side connections. For load side interconnections none of this applies.

Here’s the video with the diagram regarding this, you can clearly see that the pv disconnect is bonded with the service grounded (neutral) conductor.

You said that this would be within code if connection is on supply side. I think this means that the pv converter output would need to be connected to the near the main meter.

I also think you are saying that if the pv output is connected to a non service distribution panel, the pv becomes bonded with EGC?

See Mike holts picture / video

 

[ggunn]

You may find some old discussion or out-of-date/rouge AHJs who don't see PV systems this way but the code has mostly settled around this since 2020.

It is still a good idea to check with the AHJ over your installation to get their views on grounding, etc. for a supply (line) side interconnection. One that I deal with frequently still wants the neutral and ground separated in the PV AC disco and an EGC run from the inverter(s) back to the service, even though they have adopted the 2023 NEC. Go figure.

 

[jaggedben]

Here’s the video with the diagram regarding this, you can clearly see that the pv disconnect is bonded with the service grounded (neutral) conductor.

You said that this would be within code if connection is on supply side. I think this means that the pv converter output would need to be connected to the near the main meter.



See Mike holts picture / video

Lol I wonder what Bill Brooks said after they cut off the video. Did he agree or disagree with Mike that those were service conductors.

In my opinion Mike is incorrect and you can't go wrong treating a PV supply side disconnect as a service disconnect in every way. But the video is evidence that, as ggunn says, still not everyone sees it that way.

The most important thing is to have an effective ground fault path back to the grounded conductor of the service.

I also think you are saying that if the pv output is connected to a non service distribution panel, the pv becomes bonded with EGC?

Correct. Or rather, it could be a service panel that has distribution, the key is that is connected on the load side of the service disconnect. Just like any other circuit on the load side of the service disconnect. Unless you are.dealong wit some obsolete inverter fron 10 or more years ago.

I think the more you can stop yourself from seeing the outputs of grid-tied inverters as being any different from other alternating current circuits you've learned about, the better off you'll be.