Western Australia is the absolute best case possible for solar panel cost effectiveness though. You can't generalize from that to it being cost effective everywhere. Lots of people live in places like Europe where there often isn't strong sunshine, and there isn't a lot of available land. And as for being solved, well, that's my point. Batteries have been around for over a century. They haven't gone through some sort of exponential progress explosion that renders them "too cheap to meter". They improve but only incrementally and it's simply not enough.