The voltage level isn’t that important because voltage level shifting is easy and pretty efficient. I’ve regularly kicked 1.5 volts to over a dozen to drive LCD screens. Where this would be useful is storing intermittent energy sources like solar as hydrogen gas rather than in batteries, and that depends on how efficient the energy conversion is and how cheap the hardware is, not at what voltage it is done.
Solar cells to provide the DC voltage for producing the hydrogen (and oxygen as well, to be vented off) stored for night time use to light your garage while working on your Time Machine.....................