Backfeeding main panel with IQ8s solar system

[ImAnIdiotPleaseBePatient]

Just a hypothetical here. From what I understand, the IQ8 microinverters, when installed with the "solar backup" option, has a auto-transfer switch installed before the meter, which disconnects you from the grid in case of a power outage, in order to supply your house with power from the panels, with or without a battery.

Let's just say down the line, I hooked up a couple eg46500EX to a completely separate array, and wired this directly into my main panel. Aside from the question of whether this would violate code or not, wouldn't it guarantee that I could no longer backfeed the grid from the EG4's in case of a power outage?

 

[JCSchwarb]

Just a hypothetical here. From what I understand, the IQ8 microinverters, when installed with the "solar backup" option, has a auto-transfer switch installed before the meter, which disconnects you from the grid in case of a power outage, in order to supply your house with power from the panels, with or without a battery.

Let's just say down the line, I hooked up a couple eg46500EX to a completely separate array, and wired this directly into my main panel. Aside from the question of whether this would violate code or not, wouldn't it guarantee that I could no longer backfeed the grid from the EG4's in case of a power outage?

The EG4s are not designed to be grid interactive and will not backfeed the grid. The concern is having too much power at your load center or possibly unsynchronized power that could cause a conflict. It is not clear to me that if the EG4 system is in DC modes, if it is synced to the AC input phasing. On my setup, I built an AC input panel that tied my grid to inverter AC inputs via 60A breakers. Then I added a AC output load panel that also has 60A breakers for each inverter output. This panel is connected to my original load panel. Lastly, I added two 100A double pole breakers on input and output panels that connect both panels together in case I need to service my system. To be code compliant, all one needs is a input panel lockout that ensures the 100A breakers are off when the 60A breakers are on. A custom sliding tab can be cut and installed and CBs positioned accordingly in the panel. I am not a fan of the transfer switches as they are not necessary in an all in one inverter as the grid will nearly never need to bypass the inverters.

 

[ImAnIdiotPleaseBePatient]

Well anything can technically “backfeed the grid” if you have a power outage and are energizing the circuits in your house, but yeah… I totally forgot about the lack of phase sync, so I agree that it wouldnt work. Still learning!

 

[Delmar]

For emergency grid-down you can use a single EG4 and power both sides of your panel. Won’t be automatic because you have to manually power off all 240V breakers including the main. Install the main breaker interlock to be code compliant.

I do this with my 2700W UPSverter to backfeed the critical 120V circuits in the house (fridge, furnace, lights, etc.). When the UPSverter is disconnected I nave a convenient 240V outlet in the garage.

 

[ImAnIdiotPleaseBePatient]

For emergency grid-down you can use a single EG4 and power both sides of your panel. Won’t be automatic because you have to manually power off all 240V breakers including the main. Install the main breaker interlock to be code compliant.

I do this with my 2700W UPSverter to backfeed the critical 120V circuits in the house (fridge, furnace, lights, etc.). When the UPSverter is disconnected I nave a convenient 240V outlet in the garage.

I get that, but the point is that the IQ8 grid-tied system will actually function in a grid-down situation, and cuts off the connection to the grid before the panel with a auto-transfer switch. Was just thinking about the upgradability, with regard to adding more power later. I know it can be done by AC coupling a solark or schneider system, but was just thinking about a cheaper inverter. What you said would work, but you'd have to ditch your massive rooftop grid-tied system, which itself will function just fine even with an outage.

 

[timselectric]

Short answer is yes.
You can add any AIO after the grid-tied system.
But not ahead, unless it's AC coupling capable.