Says who ?I agree that generally for an urban domestic...

Says who ?

I agree that generally for an urban domestic installation, depending on your circumstances, batteries such as a Tesla power wall don't stack up on a pure economic basis. That's on today's prices.

However, if the solar export tax continues and batteries get a little cheaper, then they will make sense.

However, for several commercial circumstances I know of, they do. I know of people whose houses are off grid and their solar/battery system is much cheaper than running power to their properties.

Batteries for commercial peaking are now directly competitive in many cases. And, don't forget, they need much less maintenance. So for remote areas such as communication towers they are a very good solution.

Let's not forget that they are still getting cheaper. In ten years lithium batteries have reduced in price by about 85%.
We are only just at the start of the energy storage revolution.

Oh and btw. All energy storage isn't just lithium batteries you know. Flow batteries, compressed air, pumped hydro, ice energy storage. There's a whole bunch of ways to store energy.