I get the concept now. On a smaller scale wouldn't it be more practical to have two systems? One that is pumping when no power is needed and one that is generating on demand? I can imagine a valve that could be opened and closed via a switch using a battery that could open the flow to the turbine and when closed direct water to a hydraulic ram pump.

In my usecase I would use the water to power lights in a roadside stand where I would be selling homestead produce. I could imagine turning on the power for the day while customers might be coming through and in the evening when it's closed pumping water up to a reservoir. The water in the reservoir could be used to supplement power periodically or irrigate.