As part of a "standard" rooftop solar install in Ireland, one gets a hot water diverter to make use of surplus energy. So our hot water cylinder is usually hot these days at zero cost.
We had to get our bathroom re-done this year for accessibility reasons, but I pushed for a shower that could make maximal use of this free heat: immersion fed, no pressure pump, trigger-equipped showerhead. And I'm so much happier to take a shower now that it's not drawing 7-10kW and massive amounts of water. The trigger is really nice to use. Highly recommended.
A bunch of technomancers in the fediverse. This arcology is for all who wash up upon it's digital shore.