Curtailment is often a decision of the generator (I don’t know CAISO specifics but I would be surprised if it wasn’t ultimately a generator decision). If I ask

Curtailment is often a decision of the generator (I don’t know CAISO specifics but I would be surprised if it wasn’t ultimately a generator decision). If I asked you to generate power for -$15/MWh, you would refuse to do it because it would cost you money. 0 > -15. The utilities not charging negative time-of-rates is a separate decision.