Wind power is available at night. I think you are misunderstanding curtailments. It's when renewables are producing more power than what is needed and they are

Wind power is available at night. I think you are misunderstanding curtailments. It's when renewables are producing more power than what is needed and they are shut off or throttled. For the power producers getting 4 cents is better than getting 0 cents. Everyone involved in the transaction is better off. Customers get cheap power to charge their cars, and power producers get to sell energy that they otherwise couldn't. No one is subsidizing anything, the system is just more efficient.