Adding to my system. Can I combine/back-feed three inverters into one panel box?

Hello, Off-Grid I currently have two SPF 3000TL LVM-ES inverters connected to a 60 amp panel box. This currently outputs 120V.

I would like to add a SPF 12,000T DVM MPV inverter to my system.

All three inverters would be connected to the same 90kW battery bank.

Would it be better to:

1) add a second 100A panel box specifically for the SPF 12000T DVM MPV. And ground the new 100A panel box to the existing 60A box. The 60A box and solar panels are grounded to two 8’ grounding rods outside.

2) (see attached drawing) upgrade my existing panel box to a 200A. (So only one panel box). And back feed the inverters. The SPF 12000T has two lines L1 & L2 that would feed into an 80A double pole breaker. The two SPF 3000TL each have one line L1. That would “share” / both feed L1 into a 50A double pole breaker.

I want to still output 120V, with the option to output 240V.

The Neutral and Ground for all three inverters would attach to the panel box copper busbars, which is connected to the two 8’ grounding rods outside. Do I have this right?

I appreciate any help! Thank you.

The spf 12000 is not stackable according to signature solar I would buy more spf 3000 units they are stackable to 6 this would also give more redundancies if a unit has a problem not such a reduced capacity

rodrick said:

The spf 12000 is not stackable according to signature solar I would buy more spf 3000 units they are stackable to 6 this would also give more redundancies if a unit has a problem not such a reduced capacity

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Thanks. What about having it on it’s own panel box with separate batteries but grounded to the same rods as the existing system?

Putting on its own circuit stand alone is ok, when you mention grounding rods ie more than one concerns me you don’t want to make a ground loop there are several posts on grounding, also Will prouse has videos on this you should watch
grounding can be more complex than you would think, do you have any panels hooked to these aio units also everything should be on one main grounding rod

MartyByrde said:

Thanks. What about having it on it’s own panel box with separate batteries but grounded to the same rods as the existing system?

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That's fine. And they can be connected to the same battery bank. Only the AC outputs must be kept separate.

rodrick said:

when you mention grounding rods ie more than one concerns me you don’t want to make a ground loop

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I believe that they are referring to the two ground rods spaced 6ft apart at the main service. (Required by NEC code) single ground conductor connected to both, so no ground loop.

timselectric said:

I believe that they are referring to the two ground rods spaced 6ft apart at the main service. (Required by NEC code) single ground conductor connected to both, so no ground loop.

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wasnt sure how he had this grounding setup just wanted him to be aware

timselectric said:

I believe that they are referring to the two ground rods spaced 6ft apart at the main service. (Required by NEC code) single ground conductor connected to both, so no ground loop.

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Yes, they are spaced approx 8ft apart though

MartyByrde said:

Yes, they are spaced approx 8ft apart though

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8ft is fine.
6ft is a minimum.