Earlier quoted context omitted.
> but don't come with an off switch But they do. Often literally. Negative prices usually happen because of laws requiring minimum utilization, or subsides, or because they are so small and rare that it is not worth having someone on place to turn the switch.
If you want to be pedantic yes. But its not like grid operators back in the control rooms are disconnecting solar farms because the grid is oversaturated. They instead tell the fossil fuel plants to reduce their burn rate. They have to work around the instability from the renewables. That's why grid scale storage is such a key component of the future energy economy.
Since we're being pedantic, as I understand it, the grid operators don't usually tell plants what to do (outside of system stress response, curtailment, etc), the grid operator shares the forecast, and when the price forecast is low, fossil fuel plants are likely tell the grid operator they'd rather shutdown than produce power at low/negative prices. For solar plants, there's no fuel cost, and there might be subsidies, so producing at a negative market price might still be positive for the generator and there's no reason to turn it off. For nuclear, fueling schedules don't really change based on use, so there's no reason to not provide optimum power outage other than for grid stability.
Grid scale storage should reduce price swings, since storage plants will tend to show up on the demand side when prices are low and the supply side when prices are high; although perhaps price swings will become bigger when prediction fails --- if storage fills up by noon you'll have a lot of excess supply until sunset; if storage empties by midnight, you may have a lot of excess demand until sunrise.