The only systems I've seen in Northern California are grid tied and there is no battery system involved.
The inverter is chosen for its output voltage at a given current capacity, a range of acceptable DC input voltages and freq/phase matching is handled by the inverters internal electronics.
The inverter does nothing at night and it shuts down (even in the brightest daylight) when it loses it's sense signal from the mains during a power failure.
I think (but have no actual proof) that this is due to all of these systems being subsidized by State/POCP rebates. It wouldn't do for the end user to go and disconnect the thing they paid for half of from the grid and run it independently now would it? If I had just paid for a system and found out it wouldn't work in a 4 day power outage (like we had about this time last year) I would be upset. But I digress...
I have seen inverters for sale on-lone for off-grid use but don't know if they could be used in both grid-tied and off-grid modes or if the POCO here would allow it.
That said, the systems I have seen, including one capable of running a full 240V 200A service in bright daylight, all used a series-parallel network of panels to bring both the DC voltage and current up to levels that worked well with the inverter while not requiring huge feeders. It would stand to reason that a series- parallel network of batteries could accomplish the same thing. Might not be cost effective though.
