Adding AC coupled ESS to parallel Sol-Arks

[Silvard]

Hi, I'm not sure if this is the right section of the forum to post this in, but I'm currently in the design phase of a hybrid new solar system and I have some constraints and future goals that I wanted all of your expert advise on.

So far the system consists of:

2 Sol-Arks 15k in parallel.
48 kWh of HomeGrid batteries.
30kW of Solar Panels.

We're going for a net metering agreement with the local utility which has 1:1 credits which carry over monthly and 70% buy-back on total overproduction at the end of every year. There's a good chance these terms will change in the future, so there's an incentive to get PTO and lock this in ASAP and enjoy it while that lasts. That said, there's a few limitations involved:

Pulling (or feeding) more than 10kW from/to the grid consistently would put us under a different agreement that essentially erases any benefit obtained from net metering. With a sizable homelab, a couple of EVs planned and an all electric home (dryer, oven, stove, hot tub, etc. We're at least trying to go for a solar heater) and all day AC, I'm relatively confident we could hit that ceiling and likely surpass it often enough.
This is in an apartment. We do have the roof access to for the panels, but space inside is at a premium and the room dedicated to this system is already full with the aforementioned equipment.

So to get on the topic of the title, we do have big storage room in the underground garage where we intend to install a 125 amp subpanel using pre-existing wiring (we can't really run more) where we will keep the loudests parts of homelab and where the EV chargers will be connected to. Would it be possible to expand our energy storage leveraging this space and sub panel, in order to ration out the generated energy throughout the day (or, when 1:1 credits are over, maximize self consumption)? What would it take?

At first I was thinking about connecting this subpanel to the 15k's combined Gen port in Smart Load, then use an automation and some contactors to change the Sol-Ark config to Gen Input and draw power from an inverter charger connected to the subpanel, but I'm not sure if that's the best way. Does anyone have any advice?

 

[DIYrich]

Something like this might work:

Primary System (PS): 2 Sol-Ark 15k in parallel with 48kWh batteries and 30kW solar.
Secondary System (SS): Sol-Ark or another grid connected system. Inverter, Storage.

If you use the Gen Input line the max amps is 100. If you connect through the Load Line, you can get the full 125 amps.

The PS is set to Grid Peak Shave 10,000 watts.

On the SS, set to max input on grid line at 125 amps (30,000 watts). Don't know if this is possible for Grid.
Charge SS batteries whenever you anticipate loads on PS to be low (or PV producing).
Use Grid Peak Shave to somehow get some power from the Grid to charge EV, and the rest from the SS batteries.
You may be able to use TOU settings to send power from the SS Batteries to the PS.

 

[Silvard]

Something like this might work:

Primary System (PS): 2 Sol-Ark 15k in parallel with 48kWh batteries and 30kW solar.
Secondary System (SS): Sol-Ark or another grid connected system. Inverter, Storage.

If you use the Gen Input line the max amps is 100. If you connect through the Load Line, you can get the full 125 amps.

The PS is set to Grid Peak Shave 10,000 watts.

On the SS, set to max input on grid line at 125 amps (30,000 watts). Don't know if this is possible for Grid.
Charge SS batteries whenever you anticipate loads on PS to be low (or PV producing).
Use Grid Peak Shave to somehow get some power from the Grid to charge EV, and the rest from the SS batteries.
You may be able to use TOU settings to send power from the SS Batteries to the PS.

Hmm, I see. Although since the PS system is parallel the Grid Input (and the Smart Load) can be up to 200 amps. Also ideally it wouldn't be a Sol-Ark as that's a lot of functionality I'm wasting for the price (since it'd have to be another 15k at least).

Does anyone know some sort of inverter charger that can bidirectionally charge and supply power from the same connection to the subpanel? Obviously not at the same time but on "grid" loss or something?