Australia struggling with oversupply of solar power

Figuring out grid scale storage isn't easy, but the good thing about it is that you can figure out storage at slightly smaller scales to alleviate the problem somewhat, and build on that success to try to get to daily storage to meet nighttime demand, then up to weekly storage to handle fluctuations in weather, and maybe even seasonal storage to deal with seasonal variation in both supply and demand.

But storage doesn't have to just be chemical batteries, either. Some can be demand shifting, like desalination or water pumping based on excess power supply. Maybe even intermittently powering direct air capture of CO2 if there's so much excess energy they don't know what to do with it. Some can be storage of heat, whether really hot like molten salt that can run turbines for dispatchable electricity, or just at the residential scale with a bunch of distributed hot water tanks, or everything in between. There are also some storage technologies relying on gravity (pumped hydro if the geography supports it), compressed air, flywheels (could be important for maintaining grid inertia for stability).

And there's always curtailment, where you just don't generate the power, and turn off some the panels in the middle of the day.