I may have posted this link previously,
Navigant: 'Risk of slower than expected price declines' for lithium batteries but prices will fall | Energy Storage News
As of 2019, Li-ion batteries cost about USD $139 /kWh. So a 600 kWh battery (good for powering a "typical" 3 person home for about 40 hours) might cost somewhere north of USD $80,000 -- which, in AUD terms, is well into super luxury car territory. In that context, an AUD $5,000 subsidy is just a drop in the ocean -- besides doing nothing for the 50% of Australians who rent or live in unit blocks.
By 2030, Li-ion batteries "could fall to as little as USD $76 per kWh". That amount for 600 kWh storage is around the price of a new BMW X3 in the states.
But the area of solar panels required to recharge the battery would be around 20 times the size of your typical 5 kW solar system.