I don't know what Bob's got installed, but a Tesla Powerwall packs have a capacity of 13.5KWh with a steady delivery ability of 5Kw.

So at 240v this means a current delivery of just over 20A, but of course this would only last a couple of hours. For a 'normal' household you would normally expect sufficient power to run your house for the evening - assuming you had sufficient panel capacity to fully charge it during the day, of course.

Tim H.
1986 4/4 VVTi Sport, 2002 LR Defender, 2022 Mini Cooper SE