I remember driving through the Mojave and seeing both large solar fields and windmill fields and thinking about the huge impact that had to have on the desert.
Looking at it from a different view, Forget all the rest for a moment. Try to harden them for any potential terrorist or other attack and watch what happens.
This applies to all power generation facilities but most of them are more compact, can be better hardened/defended and easier to restore.
Then, how many individual panels or mills have to be disrupted to take the entire grid down?