But that's only during peak solar output, which coincides with reduced electricity demand. This is why often electricity retailers will sell power to consumers for free or even pay us to use energy during these hours, and part of the reason why the solar tariff feed-in prices have been significantly reduced.
The problem is we don't have anywhere near the amount of battery storage to get through non-solar output hours, in particular the peak evening hours, without relying on baseload power (coal, oil, gas). This is a problem that will be around for decades, and then the lifespan of these batteries is about 20 years, so eventually they will need to be replaced unless superior technology comes around, so this will no doubt be a cost and supply issue in the future. We know battery storage is already expensive, imagine increasing this to a global scale.
I can't see coal, gas and oil going anywhere for quite some time. Already the coal power stations have been extended in Victoria and NSW for a few more years. Then even if the power stations were to close, and we somehow got into a position of "sustainable energy" (I use those words lightly as renewables still need to be replaced), fossil fuels will still continue to be one of the largest exporters for Australia, so third-world countries will continue to rely on Australia to meet their energy needs.
