Depends on your usage, your roof and the size of your system. Here’s what it’s looked like for two homeowners.

Steven Bell runs a heavy usage household in Port Kembla. He tracked his own figures: about $1,350 of grid electricity over the seven months before his battery, and $120 over the seven months after. His direct debit today is $5 a month.

Helen’s bill was “quite a shock every month”. She installed the largest system her home could fit so she could make the most of the free energy hitting her north-facing roof.

Those are their reported results, not guaranteed outcomes. The reduction comes from the same place every time. Most homes use most of their power in the evening, when grid electricity is dearest. A well-sized system lets you run on your own stored sunshine through that peak instead of buying it back from the grid.