I have wondered why these are not used in offgrid solar applications.
But maybe they are?
Also, how fast will it charge and discharge? My solar inverter can convert DC to AC at 9 kW continuously. That means nothing if the batteries can't discharge that quickly -- otherwise I'm pulling from the grid. The same with charging quickly (my 10 kW solar panels need somewhere for that power to be stored if my home isn't using the power, but that means the batteries have to be able to accept up to 10kW charge from my charge controllers at any given time). If the batteries don't have rapid charge and discharge they're practically useless for running a home with.
They are. I just bought some to replace my old flooded cell batts. Supposed to last 3 times longer plus can be cycled deeper. We'll see.