AC coupling

[carlosnindy]

I currently have a 10000w Solaredge inverter with 11.4kw panels and a 6000w Growatt inverter with 5.9 kw of panels that are both grid tied. The Growatt back feeds a sub panel that is tied into the main panel and the Solaredge is backed directly into the main panel. I currently do not have any battery backup.

I am thinking of modifying the system to allow for battery backup using AC coupling into either a Sol Arc 15k or EG4 18k. I would replace the Growatt inverter with the new inverter and then feed the Solaredge inverter into the gen port on the new inverter.

My question is would I have to create a new sub panel that has my grid lugs and tie in the new inverter grid connection do a whole home backup and have the load port connected to my old main panel? If I understand things correctly I can’t have the grid and load connections of the new inverter tied into the same panel.

 

[1201]

Are you trying to use batteries for grid down situations? Or just to capture and use more of your production?

 

[carlosnindy]

Are you trying to use batteries for grid down situations? Or just to capture and use more of your production?

I would like to use batteries of grid down and eventually for when my new metering expires.

 

[1201]

I would like to use batteries of grid down and eventually for when my new metering expires.

You'll need a critical loads subpanel for those loads you want to have in a grid down scenario.

 

[BentleyJ]

Yes, you are correct the Line & Load side of the inverter cannot be connected to the same panel UNLESS the panel has an interlock kit to prevent both the grid and inverter breaker being ON at the same time. This is not an ideal situation since there can be no grid pass-through in this configuration and the built in inverter transfer switch is no longer useful.

If you wish to do whole home backup of both the main and subpanel, a Line Side tap is needed, after the meter but in front of the Main breaker.
This is usually done with a double throw safety switch.

 

[carlosnindy]

Yes, you are correct the Line & Load side of the inverter cannot be connected to the same panel UNLESS the panel has an interlock kit to prevent both the grid and inverter breaker being ON at the same time. This is not an ideal situation since there can be no grid pass-through in this configuration and the built in inverter transfer switch is no longer useful.

If you wish to do whole home backup of both the main and subpanel, a Line Side tap is needed, after the meter but in front of the Main breaker.
This is usually done with a double throw safety switch.

What switch would you recommend

 

[BentleyJ]

Here is an example: These double throw devices rated for 200A are costly but having it in place as a maintenance bypass is really nice if you need to electrically isolate the inverter for service or replacement but still need utility power feeding into the main panel.

Siemens General Duty Double Throw 200 Amp 240-Volt 2-Pole Outdoor Non-Fusible Safety Switch DTGNF224NR - The Home Depot

Double Throw switches are intended to transfer loads from 1 power source to another. All 2 and 3-pole double throw switches are suitable for use as service equipment including non-fusible versions when

www.homedepot.com

The other question is how far away from the meter is the inverter going to be? Once the line side tap is made and the double throw switch is installed. How far away is the Over Current Protection Device (Circuit Breaker)?

Backing up the Main Panel with a line side tap has some challenges with regard to code compliant, safe wiring.

 

[carlosnindy]

Here is an example: These double throw devices rated for 200A are costly but having it in place as a maintenance bypass is really nice if you need to electrically isolate the inverter for service or replacement but still need utility power feeding into the main panel.

Siemens General Duty Double Throw 200 Amp 240-Volt 2-Pole Outdoor Non-Fusible Safety Switch DTGNF224NR - The Home Depot

Double Throw switches are intended to transfer loads from 1 power source to another. All 2 and 3-pole double throw switches are suitable for use as service equipment including non-fusible versions when

www.homedepot.com

The other question is how far away from the meter is the inverter going to be? Once the line side tap is made and the double throw switch is installed. How far away is the Over Current Protection Device (Circuit Breaker)?

Backing up the Main Panel with a line side tap has some challenges with regard to code compliant, safe wiring.

Inverter will be 15-20 feet from the meter and main panel

 

[BentleyJ]

Inverter will be 15-20 feet from the meter and main panel

I believe the Inverters you mentioned above do have a built in AC main breaker but at 15 to 20 feet from the panel, that is a good length of unprotected wiring. Is this installation going to have a permit and be inspected? There may be a requirement for fuse or breaker near the line side tap location to protect everything downstream.

 

[carlosnindy]

Probably no permit