> were high because of natural gas shortages and coal generator closures, and that the payback period on storage and solar is down to 7 years
That isn't as compelling as you might think. If they screwed up their energy grid by closing down gas and coal generators then (1) solar would look better than nothing and (2) would have a short payback period.
That fact could just as easily be cited in an argument as "these clowns really need more gas and coal". The lack of fossil fuels is linked to very high power prices.
> Renewables drive down the cost of power [1]
Your link doesn't actually support that. It says they drive down the cost of wholesale power. That is how it typically plays out when countries go heavy on renewables (same thing happened in Germany). Wholesale prices drop, retail prices rise because of there is too much energy when it isn't wanted.
> The "South Australia Big Battery" at the Hornsdale Power Reserve, recently expanded, has saved electrical consumers $150 AUD million
Again, proabbly evidence of a mismanaged grid. Given that it was built in SA rather than somewhere important, it seems likely Big Battery is fixing up losses from installing an unstable amount of wind and solar.