Or convert excess to hydrogen and provide resilience, or have arrangements for industry to consume the excess. Or ramp down your generation at those times. Or shift excess to neighbouring grids.

No, there is pumped storage. Honestly, despite the plethora of start-ups claiming to have a solution (sodium batteries, molten-salt, etc) The only really proven way to store electricity for later is pumped storage, but that relies on geography (hills) which not everyone has. Batteries are great for phones, and cars but they simply don’t scale to countries.