when wind blows, if you're running a nuclear or coal plant, you cannot sell any of your produced electricity until your wind/solar competitors sold everything they produced
In a free market wouldn't coal be at a similar disadvantage? Solar/wind would sell for any price above 0 but coal could not sell below the cost of the resource. When the wind is blowing and the sun is shining the renewable utilities will always sell at market price - even if that drives the market price down to almost nothing. We really need to develop a market that can handle this. Probably that will mean dropping feed in tariffs and charging the consumer a market rate rather than subsidizing the consumer. New technologies will be required to help manage this. For instance your car would charge automatically when the rate drops below 5 cents (and possibly sell excess when the the price is quite high). It is going to require a revolution but given the trajectory of the cost of solar - that revolution is coming one way or the other.