As I write this from South Australia, our grid (up to 3GW of demand, ~2 million people) is more than entirely powered by rooftop solar alone (https://explore.openelectricity.org.au/energy/sa1/?range=1d&...). The only synchronous generation, gas turbines , is providing just under 4%.

This is a regular event outside of the winter months, and has been for some years now. South Australia has a mixture of solar, wind, and gas generation, with some large batteries as storage.