Grounding for Off-grid + Grid back up+battery bank+generator back up+ grid transfer switch.

[pgoldston]

Just like the title says can I get a best practices grounding for a system with multiple parallel inverts Off-grid + Grid back up+battery bank+generator back up+ grid transfer switch.

I have searched and read the last several days. I information for pretty much on off grid systems but not anything on parallel inverters with grid back up.

From what I understand, should only be 1 bonded location, from there everything else should be linked at a common bus bar.

So Ac power comes into a main breaker disconnect box, that box has a bonded ground/ neutral to grounding rods linked together.

If each component has its own path back to the main busbar/rod then no ground fault or loops should arise.

Is this correct?

L1 L2 G N goes out to respective inverters, each panel unbonded but panel should be ground back to the green ground wire.

Battery pack 51.2v 2000ah combined rating, after bms pos and negative run to a breaker, a ground wire comes from breaker to the main panel grounding bus bar. Pos neg terminals go to inverter bus bars for the inverters to pull from.

Inverter ac out would go to main house distribution panel. L1 L2 G N restive locations and linking the G back to the bus bar. This panel and any subsequent sub panels would not be bonded.

PV panels all get linked together panel to panel with a ground wire. This does not get its ground rod, instead would go to the main ground rod or to grounding bus bar.

Transfer switch would just be a full by pass, since the main panel is bonded should be no other changes?

 

[Samsonite801]

Just like the title says can I get a best practices grounding for a system with multiple parallel inverts Off-grid + Grid back up+battery bank+generator back up+ grid transfer switch.

I have searched and read the last several days. I information for pretty much on off grid systems but not anything on parallel inverters with grid back up.

From what I understand, should only be 1 bonded location, from there everything else should be linked at a common bus bar.

So Ac power comes into a main breaker disconnect box, that box has a bonded ground/ neutral to grounding rods linked together.

If each component has its own path back to the main busbar/rod then no ground fault or loops should arise.

Is this correct?

L1 L2 G N goes out to respective inverters, each panel unbonded but panel should be ground back to the green ground wire.

Battery pack 51.2v 2000ah combined rating, after bms pos and negative run to a breaker, a ground wire comes from breaker to the main panel grounding bus bar. Pos neg terminals go to inverter bus bars for the inverters to pull from.

Inverter ac out would go to main house distribution panel. L1 L2 G N restive locations and linking the G back to the bus bar. This panel and any subsequent sub panels would not be bonded.

PV panels all get linked together panel to panel with a ground wire. This does not get its ground rod, instead would go to the main ground rod or to grounding bus bar.

Transfer switch would just be a full by pass, since the main panel is bonded should be no other changes?

Need to know more about the inverters in question. Many of them have a built-in N-G bond relay which closes when the inverter is on (opens in grid bypass mode)... Multiple inverters may have N-G bonding (with or without relay) possibility on any of them. Many models of inverter can have an N-G bond screw that can be removed to disable N-G bonding possibility. Some inverters, the N-G bond relay behavior can change with a simple firmware update.

 

[pgoldston]

It is the SRNE HYP series Inverters. I have looked through the website, fired emails and read several manuals and the only thing about the AC ground it mentions is to keep it as short as possible.

 

[Zwy]

It is the SRNE HYP series Inverters. I have looked through the website, fired emails and read several manuals and the only thing about the AC ground it mentions is to keep it as short as possible.

Measure for continuity between N and G with no wires attached to the unit.

If there is continuity, then the inverter most likely has an internal bonding relay that will bond N and G under inverter power. If so, you have a few options such as disconnecting the N/G bonding relay or using a 3 pole neutral switching transfer switch where N from backup grid power will not play into this. You will need a main panel ahead of the inverter and a panel after the inverters.

If no continuity, then I would bond in the electrical panel after the inverters

 

[pgoldston]

Measure for continuity between N and G with no wires attached to the unit.

If there is continuity, then the inverter most likely has an internal bonding relay that will bond N and G under inverter power. If so, you have a few options such as disconnecting the N/G bonding relay or using a 3 pole neutral switching transfer switch where N from backup grid power will not play into this. You will need a main panel ahead of the inverter and a panel after the inverters.

If no continuity, then I would bond in the electrical panel after the inverters

Most of that makes sense. I was able to make contact concerning the inverter. I was told that it does not have relay but does have a neutral point for grounding is the exact words used. Dont know if anything is lost in translation but I will complete the above test and see what happens.

Couple of items just to confirm, testing with no wires attached -- This means NOTHING and the box is dead?

3 pole transfer switch - I am guessing this is the relay/ bond is disconnected that it would switch the a panel bond? As for pain ahead and after, both being bonded? Can they be bonded to the same grounding rod?

If there is no continuity on the test, is there any particular reason to bond the neutral/ground after the inverter versus prior?

I greatly appreciate the help

 

[Zwy]

Most of that makes sense. I was able to make contact concerning the inverter. I was told that it does not have relay but does have a neutral point for grounding is the exact words used. Dont know if anything is lost in translation but I will complete the above test and see what happens.

Couple of items just to confirm, testing with no wires attached -- This means NOTHING and the box is dead?

Nothing connected, just like it came out of the shipping box, so yes, it will not be powered up. Most of these use a normally closed relay and only switch when the unit is under grid power.

3 pole transfer switch - I am guessing this is the relay/ bond is disconnected that it would switch the a panel bond?

If the unit bonds under inverter power, the 3 pole would allow any N-G bond ahead of the unit to be bypassed so there would be only one bonding location.

As for pain ahead and after, both being bonded? Can they be bonded to the same grounding rod?

Only one N-G bond. First thing to determine is if the unit bonds N-G or not. If it doesn't, you can rely on the N-G bond ahead of the inverter at the main entrance panel from grid. However, you will also mention a generator, so that can play into the bonding location.

If there is no continuity on the test, is there any particular reason to bond the neutral/ground after the inverter versus prior?

It makes it easier if you have a non bonded generator. No matter where power comes from, the N-G bond will always be at the same location and only one bond. You also mention a transfer switch. It might be best if you post up a rough diagram so members can see what you are planning.

You did not mention whether this will be inspected or not, that also can determine where N-G bond will need to be.

I greatly appreciate the help

Have you reviewed the information by Filter Guy in the Resources section? Click the download button top right corner and also look at Part 2. https://diysolarforum.com/resources/grounding-made-simpler-part-1-ac-houshold-grounding.157/