The electrical grid is mostly built on 19th-century electromagnetomechanical rotating-shaft generation, stabilized using mostly electromagnetomechanical controls designed around the rotational inertia of the shafts. An overloaded grid shows frequency droop as the shafts slow down. Solar cells and giant rechargeable batteries provide generation that is purely static, with electronic-speed controls, decoupling overload from frequency droop. Australia has already seen a case of a Tesla 7 MW battery bank responding instantly when a coal plant tripped. The battery was online before the coal plant finished tripping. Interesting times lie ahead for stability engineers.
As wind and solar sources become more common, the problem of responding to their variability will become more severe. Smart Grid will encourage innovative means of matching load to generation on a moment-to-moment basis. Interruptible service will become more common. How would interruptible service, specifically for overnight residential charging of electric cars, be implemented and billed?
