Episode 9 – Battery storage – adding a second Tesla PowerWall

2021 – Battery options modelling

In September 2020 we installed our first battery at Sturt Apartments, Christie Walk. You can read the story of our modelling, battery choices and lessons learned in Episode 7 – Battery storage – Tesla PowerWall 2

Everything had gone to plan with the installation of the battery; performance was as expected. The savings generated by our PV upgrade and the battery were flowing into our Green Fund, enabling us to begin planning for the installation of our second battery.

Our modelling indicated that our 21kW PVs were generating enough power to usefully support up to about 55kWh of battery storage, corresponding to 4 x Tesla PowerWall 2 batteries. In cost-benefit terms, a sweet-spot would be with 2 batteries. In the depths of winter in July – on many days – we’d still generate enough spare power to fully charge the batteries for use after sundown.

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