Solar panels don't care if the energy they could produce isn't consumed.

Wind generators can be feathered and breaked until they stop rotating and generating.

Hydro-generation dams can simply close their water intakes and stop generating.

The things that have problems stopping generation are not renewables, they're things like nuclear power plants.

Negative energy prices are not a technical problem.

Negative energy prices are due to Market systems being used to decide who stops generating if supply exceeds demand by having the individual suppliers look at the market price for their product and decide to stop/start producing or not by themselves.

Because electric power supply/demand balance changes way faster than said market signals are produced and processed ultimatelly to decisions to stop or start generation, you end up with prices overshooting and undershooting the ideal price point for the supply/demand balance, and sometimes the undershooting results in negative prices.

Negative energy prices are the result of the political choice of using market systems rather than some kind of centralized control.