Wildfires, more than likely.

They turn off all the transformers because if the fire hits them they will explode and make even more fire, with the potential of blowing more out further down the line where there isn't even a fire.

On top of that, since their move to green energy, they have no ability to stockpile energy or increase production to make up for the drain.

If anything stresses a green energy grid you have roaming brownouts. It just can't keep up. If you have a coal plant, you just put more coal on the fire. You can't beg they sky to make more wind or the sun to shine brighter.

They really set themselves up for any disaster to send them into a tailspin.