What happens to all the power being generated by all the wind farms, solar cells, and nuclear and coal plants (and hydroelectric?)? My understanding is that tho

What happens to all the power being generated by all the wind farms, solar cells, and nuclear and coal plants (and hydroelectric?)? My understanding is that those can't go on- and off-line rapidly (one of the big advantages of natural gas plants). Is there a way to "ground" the excess, or does that end up causing problems with over-supply in the parts of the grid still online? Also, won't the flux from the solar storm cause current to flow through power lines, regardless of what is actually connected? I suppose the transformers would still be protected, but there may still be damage to grid.