The average price of power in Australia is 34 cents per kWh. The average Aussie spends A LOT more than $0.20 per day.

GP isn't talking about a full day's use, but "free electricity for an hour or two each day (or even each week)."

The whole reason to spend the money on the battery is so you can use the free power for a lot longer than an hour or two!

You'll want to draw as much power as possible while its free, and use it duing peak times.

7.3% return, not bad. As battery prices drop it will get even better.

It's not 7.3% return rate. There's some depreciation you need to add there.

If you're going to depreciate the battery then your return will be substantially greater than 7.3%. You can't use BOTH the capex AND the depreciation as your denominator, choose one.

Where I live, $1000 would get you about 3kWh of battery power, which would pay for itself in a couple years