Bazz asks "what do we do on calm overcast days?"

The chances of there being no wind or sun, across the entire continent of Australia are about the same as that of a nuclear power plant blowing up.

We can easily supply base load using wind generators along the Bight and Great Divide and solar plants in the North West, West, Centre and up the western slopes of the Divide. The setup cost is comparable to nuclear power, they come online more quickly, maintenance cost is miniscule by comparison, and there are no decommissioning costs as they do not create poisons that last for millions of years. people keep quoting 250,000 years but that is only the half life of plutonium!

Hmmm, just read the referenced molten salt system.
It does seem a distinct possibility.
The claimed 17% efficiency is probably high enough seeing that the
initial energy input is "free".
Someone needs to work out what are the losses of tranmission of power from
the best solar sites to the point where the load is used.
Additionally the suggestion that the southern coast be fitted with wind
farms may not be practical due to transmission losses unless very high voltage DC lines are used.
Will the enviromentalists object to covering
the coastline with wind farms ?
Whatever capacity is needed must be multiplied by four to get the size
of wind farms. ie for each megawatt of demand four megawatt of windfarm
must be installed. The EROEI suffers considerabley when that is considered.