When it (hybrid inverter) is operating in parallel with the grid, it changes mode to grid tied (no longer grid-forming), just like any other GT inverter, and essentially is a current source. That is why it is difficult to work with a generator when the local site is islanded from the grid. A finite set of varying loads, a dumb generator, and a current source that does not have comms with the generator source. If the generator was smart and could vary frequency based on load, to signal curtailment to the inverter, it might work, but dont think any generator has that capability.
Powerwalls do not support any direct (parallel or serial) connection with generators. The only supported configuration is via a transfer switch that completely isolates the Powerwall from all generators.
OK, but what would happen if you were to connect a Powerwall 3 and gateway behind an ATS, as in
That's not how Tesla wants it. The ATS should be down stream from the PWs.
Assuming there's an engine generator connected to the ATS as well, then if the grid goes out, the PWs would take over the loads immediately. Then once the generator is up and running, the GW3 would likely eventually decide the grid is back and transfer back to on-grid mode. At which point if the PW3 ever decides to try to net export to the grid, due to either solar in excess of the loads, or TOU programming, it would backfeed the generator and damage it.
Yeah. Duh.
You are basically talking about creating HVDC microgrids. Companies like YouSolar has been doing that for a while. Tesla PW creates its own AC microgrid and does not support any DC power source directly. Some people have hacked generators to run AC-DC power supplies to feed into PV microinverters that in turn feed PWs. It works but not very efficient.
A grid-tied battery is a current source or sink, and the amount and direction of current is determined by some kind of controller. Typically that controller incorporates CT measurements of site consumption to achieve goals like 'self consumption', but sometimes it's also just determined by a schedule. At a fundamental level, it could be determined by anything you like, and is only fundamentally limited by SOC.
