> Water is a lot easier to store than electricity. Desalinate while the sun is shining to fill a reservoir that you can pull from 24/7.

Cheap to store, expensive to transport. Desalinisation only makes sense if you are near the coast and short of water. Further inland it becomes uneconomical.

The Earth is not short on fresh water, the problem is getting fresh water where it is needed.

True, but it isn't energy, and desal requires firm generation, so you're not using renewables that would've been curtailed but instead competing with load that needs consistent power. Still hopeful considering the cost decline curve of utility scale storage, but it isn't a silver bullet based on solar being free at noon.

Why do you need to desalinate it to use it for energy storage? Seems like an unnecessary step that would not increase the gravitational potential energy at all.

Pumped storage hydro is a way to store energy, but also can dispense water.