Michael Vorstermans ran the numbers on Tesla's Powerwall home battery when it hit the market last year, and it didn't add up.

Our typical 4,800 kWh household in
 Adelaide can beat all current grid-only
market offers by installing a PV and battery
system and selecting the best retail offer
 to provide their residual grid consumption
and export their PV production surplus.

Michael Vorstermans ran the numbers on Tesla's Powerwall home battery when it hit the market last year, and it didn't add up.

The 6kWh battery could store less than half his Rydalmere household of three's daily power usage and would take 18 years to pay off – more than twice the warranty period.

But when Tesla released the Powerwall 2 a few weeks ago, the game had changed. It had more than twice the capacity – 14kWh – and the price had come down to just over $10,000.

Mr Vorstermans calculated it would take between six and nine years to pay off – and ordered one for delivery in February to store power from his 4kW of solar rooftop panels.

Read the Financial Review story - “Tesla's Powerwall 2 can pay for itself in six years, then its electricity is free.”