@UP8 I wonder if something like this could be used in a smaller scale?

Some modern sailboats with solar panels, wind or hydro generation, can sometimes produce more energy than can be stored in the batteries.

There are various electric #SailDrive systems that include a diesel "range extenders", such as Oceanvolt’s hybrid system https://oceanvolt.com/oceanvolt-blog/hybrid-electric-marine-propulsion-oceanvolt-48v/. It would be nice if excess power could be used to create diesel when the batteries are full. It might be better than larger battery banks.