Assuming SpaceX can deliver it. They've failed to do a successful test flight with even a fraction of the officially planned capacity. Who knows how long it will take them, if they can even pull it off, to deliver it.
The answer is somewhere in the neighborhood of as much as one can safely store and afford accepting that batteries have a short life. Much like wells in cold climates the batteries should be in an underground insulated vault made from higher quality concrete as to keep fire hazards away from the home. That is also where whole-home generators and fuel belong, in their own vault so they can be easily maintained without having to rent an excavator to dig out the tank.
https://enron.com/pages/the-egg?srsltid=AfmBOoqW03cqyIhQ0OlG...