Tesla has announced the impending arrival of the Powerwall 2 at a promised price point that, on the surface, looks very compelling: $10,150 fully installed1, or  23c per warranted kWh.

It seems particularly impressive when you consider that in Sydney and Perth, time-of-use tariffs can go to 50c per kWh during peak periods.

That’s 23c for electricity from a battery vs. 50c for grid electricity. Surely that makes the Powerwall 2 a no-brainer investment for people on such a tariff?

I decided to look a little deeper into the economics of using Australia’s cheapest battery2, on Australia’s highest grid tariffs.  Unfortunately I found that high peak rates are not nearly as good for the economics of the Powerwall 2 as they seem.