Nailed it.
We need a solar grid that can meet our demand during a 9-hour, overcast, low-angle winter day. That same grid will be producing more than 4 times as much power as we need during a 15-hour, high-angle summer day, even after we include air conditioning loads.
We need massive, seasonal loads to soak up that excess power and keep solar profitable.
Fake butter isn't going to do it, but things like desalination, hydrogen electrolysis, and Fischer-Tropsch hydrocarbon production are all likely candidates.