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.
You're talking about Thermal Storage, indeed a complex and costly field in the research for out-of-optimal conditions for electricity production I.e. nighttime for solar power
I know that's a thing I just don't know how it compares to what OP is talking about
Turbines are extremely efficient (close to 100%), and almost all large scale power sources use them already (nuclear, hydro). Powering the pump isn't "lost" energy, it's the energy transformed from solar into potential energy from pumping.
Of course not all of the energy used to power the pump is lost (that's the whole idea) but there is still some energy loss. Maybe it's only a small amount like you say with the turbine but that's what I was referring to.
Yeah, I see what you mean.