The problem is that Australia is so married to coal that they have no national electrical grid strategy, including transmission line investment, so it’s harder to get generation to load centers (“follow the sun” generation”). They also don’t have natural gas to fill in when renewable generation dips (unlike the US).
The solution is going to be a lot of utility battery storage (Hornsdale Power Reserve Tesla battery is currently being expanded, for example), more renewables, and actual transmission infrastructure investment.