All Brisbane Electrical UPDATES, page-3

The simple fact of the matter is that home battery installations, across most of Australia, are not economical. You would spend more on the batteries than you would save on the power.

The major exceptions are in remote areas with unreliable or no connection to the main grid: the cost of connecting to the grid in such areas would be significantly higher than installing solar panels with a decent battery backup.

Last I looked at the ZCell, its cost was a bit more than the Tesla Powerwall. Round trip efficiency (the amount of power you get back out for the power you put in) is also lower, at around 80%. But against that, the chemistry of a flow battery versus lithium means that the lifespan of the ZCell should be significantly longer, and there are other technical advantages.

Ultimately, though... it's down to price. If you're on the electrical grid, home batteries just don't make financial sense at this stage. (Note that there are other factors that might play into this, such as wanting to be self-sufficient in the event that the main grid goes down. But that's not an economic argument.) If you want to spend the money anyway for (for example) environmental reasons, there's nothing wrong with that - just be aware that you won't save what you spent.