Question about wiring my inverter to an existing home sub panel.

[Valorton]

Hello and thanks for your time.

I have a 200A main panel that powers the AC/FAU, Water Heater, Garage Doors and has a 240V/100A breaker that goes to a Sub Panel inside my house. The sub panel powers everything else in the house. It is connected/wired with two hot lines, neutral and a ground. The main panel is G/N bonded, the sub panel has G/N wires that are separated (not bonded).

I am running two EG4 6000XP in parallel and wired to a combiner box with two hot wires, a neutral and ground wire connection for each. It powers an outlet I installed next to it. The inverters have the N/G bond turned ON and the combiner box has the G/N wires separated. The inverters are on PV and battery only and have no grid connection with the main.

I want to run inverter power from the combiner box to the Sub panel inside. (see diagram) I have room to install a breaker in the sub panel that I can connect to my inverters combiner box, then turn off the sub panel breaker that connects it to the main.

Two questions...

1. Is this feasible?

2. If it is... how should I handle the G/N wires from the inverter since the ground and neutral will still be connected to the main panel even with the breaker off.

 

[BentleyJ]

The inverters have the N/G bond turned ON and the combiner box has the G/N wires separated.

The attached diagram says N/G is OFF?? as it should be for your proposed wiring diagram.

I want to run inverter power from the combiner box to the Sub panel inside. (see diagram) I have room to install a breaker in the sub panel that I can connect to my
inverters combiner box, then turn off the sub panel breaker that connects it to the main.

1. Is this feasible?

Yes, the new 100A, 2 pole breaker in the subpanel should have an interlock plate installed so the main and inverter backfeed breaker are never on at the same time.

2. If it is... how should I handle the G/N wires from the inverter since the ground and neutral will still be connected to the main panel even with the breaker off.

The answer is in the question. The N/G bond is active all the time regardless of the breaker positions or source of power, utility or inverter, so you don't need to to do anything as long as all the neutrals and grounds are each connected all the way back to the main panel.

 

[TM48]

Be sure to include an interlock to the main and back fed inverter breakers. The 6000xp is an off grid only inverter.

 

[Recovering EE]

You're doing what I did, except I'm only using a single 6000XP.

I added a two-pole transfer switch (L1 and L2 switched only) between the main e-panel and the sub, branching off to the 6000XP. I tied the 6000XP Neutral and Ground to the main house panel's N and G (conveniently within the transfer switch box), and they both go back to the main, and also on to the sub.. I've got the 6000XP N-G bond disabled.

 

[hwy17]

You can use the main panel's NG bond as your bond even when the main panel to subpanel breaker is off. Just wire L1/L2/N/G from the inverter's load side to the subpanel.

Ideally, interlock the backfeed breaker with the subpanel main breaker, for safety.

Additionally, you can run L1/L2 from the main panel to the inverter if you want to add passthrough while going around your existing feeder.

See my diagram here, it will work with or without the main panel to inverter grid supply connected:

Simplified Reacharound Subpanel to CLP conversion diagram

This is my now simplified and non controversial diagram attempt for a typical circuit idea for the conversion of an existing subpanel, with existing 4 wire feeder, into a CLP without touching the feeder. It requires that the subpanel has a main breaker or backfeed breaker such that the primary...

diysolarforum.com

 

[Valorton]

You can use the main panel's NG bond as your bond even when the main panel to subpanel breaker is off. Just wire L1/L2/N/G from the inverter's load side to the subpanel.

Ideally, interlock the backfeed breaker with the subpanel main breaker, for safety.

Additionally, you can run L1/L2 from the main panel to the inverter if you want to add passthrough while going around your existing feeder.

See my diagram here, it will work with or without the main panel to inverter grid supply connected:

Simplified Reacharound Subpanel to CLP conversion diagram

This is my now simplified and non controversial diagram attempt for a typical circuit idea for the conversion of an existing subpanel, with existing 4 wire feeder, into a CLP without touching the feeder. It requires that the subpanel has a main breaker or backfeed breaker such that the primary...

diysolarforum.com

Thanks for your reply. I was also wondering, if my grid power goes out and I continue to power my house with my inverter, is there any chance I would be sending power back to the grid on the neutral wire because it's connected to the main panel? Power that could get someone hurt?

 

[DIYrich]

Thanks for your reply. I was also wondering, if my grid power goes out and I continue to power my house with my inverter, is there any chance I would be sending power back to the grid on the neutral wire because it's connected to the main panel? Power that could get someone hurt?

power on the neutral wire should sink to ground.

 

[hwy17]

Thanks for your reply. I was also wondering, if my grid power goes out and I continue to power my house with my inverter, is there any chance I would be sending power back to the grid on the neutral wire because it's connected to the main panel? Power that could get someone hurt?

If you stacked multiple fault conditions on your side and the utility's anything's possible, but it's the same safety profile as a backup generator which usually also use the neutral.

 

[Recovering EE]

Thanks for your reply. I was also wondering, if my grid power goes out and I continue to power my house with my inverter, is there any chance I would be sending power back to the grid on the neutral wire because it's connected to the main panel? Power that could get someone hurt?

Assuming that at the main e-panel there's a solid N-G bond, and G has a solid connection to a Ground rod, no.