South Australia has so much solar, at times there is zero grid demand. It is a management nightmare for grid operators, but that's what they're getting paid for (instead of generation, which is shifting to direct payment from consumers with solar on their roofs).

The future of grids is orchestration between variable demand and variable generation, along with pumped storage, battery storage, and long distance transmission.

If everyone is producing electricity, who pays the bills?

Same people who pay for the roads and traffic signals?