Negative Price

A negative price happens when a wholesale electricity price clears below zero for an hour: generators pay to keep running rather than switch off. It occurs when supply from sources that are cheap or costly to stop (wind, solar, nuclear, some subsidised contracts) exceeds demand plus what can be exported, and other plants would rather pay a small fee than shut down and restart. It is a signal of temporary oversupply, not a sign the grid is broken, and it tends to cluster around the sunniest or windiest hours.