Not too many big thermal plants are bidding that way. The ones that aren't dispatchable at all don't actually offer into the market as a price maker. Instead, t

Not too many big thermal plants are bidding that way. The ones that aren't dispatchable at all don't actually offer into the market as a price maker. Instead, they just act as price takers and likely make up for it by being part of a vertically integrated utility playing in the energy market - as in they can have any losses factored into rates. It is far far more common to have wind/solar offering in negative prices as they want to run at any cost to take advantage of the extremely lucrative subsidies. There is limited transmission available, so those various wind farms are competing against each other to just run. Also, you can have negative prices just due to congestion.