No, we are NOT prepared.
There are 3 main grids in the US: The eastern grid, the western grid and the Texas grid (owned by Texas). They are not connected to each other, so if one goes down it can’t get energy from another.
A well placed EMP burst could easily knock out most power in the US.
A strong solar event could knock out all power. For months.
We do NOT have spare transformers for the large distribution stations and the transformers we do have are made in... China.
Good summary.