To make solar power viable, we need a solution for overnight energy storage.
Batteries are complicated.
Do you know what isn't? Water go up. 
To make solar power viable, we need a solution for overnight energy storage.
Batteries are complicated.
Do you know what isn't? Water go up.
I've also seen a version of this that uses an electric locomotive that moves a big weight up and down a slope.
Personally I think we should put big weights on pulleys in every high rise, like a grandfather clock.
Pumping water is a lot more efficient and easy. You need a lot of mass to make it worthwhile.