The fun part is that we're still well before the point when this even matters.
Almost 60% of the US grid is still fossil fuels, with around half of that still happening during the day. Which means you can get down to ~30% fossil fuels without any storage at all because all you do is go from burning fossil fuels during the day and at night to burning fossil fuels only at night.
only natural gas plants can do this. a coal plant cannot spin up just for the night and turn back off when the sun comes up - it's incredibly inefficient and probably causes more premature wear/tear too.
Other countries are better positioned. e.g. UK has really spiky wind energy. Right this second more than half the grid is wind. Which is both cool and problematic for managing the grid.
Grid scale cheap storage would dramatic help manage that chaos