The electricity price already turns negative in quite a few countries with larger shares of renewables at peak times, but isn't really being exploited right now due to the high capital cost and low usage for most things that need electricity.
Which is another way of asking "When will people stop consuming more power?"
Previously, we had finite energy resources that were limited by the fuel (oil, coal, gas) or regulation (nuclear).
Suddenly, there is no limit. You could build as much solar as you had panels + installers for.
Which really turns future energy on its head. Why not build more forever? And if there's excess, build more energy consumptive industry...