In message , Andy Dingley writes
Do you know whether they charge a yearly licence fee? My BiL's Dad (now sadly no longer with us) had a 5kW hydro plant[1] on the stream that ran through his property near Zennor, but that was one of the questions I never asked him.
It was originally 110v DC when it was installed, when the house was built in the mid-'30s, but the dynamo was replaced by a 5kW 240v 50c/s alternator in the '50s. When almost all the other electrical equipment was off, mostly overnight, all the spare power was dumped by immersion heaters into big, cellar-mounted, insulated water tanks (supplied from the house's own spring, as was all the house's water including drinking water) giving almost-unlimited hot water.