I have a 12L (12 litters per minute) tankless water heater. Uses 24v for exhaust blower and ignition… all from the power I make with my solar panels. I have had mine for over 6 years and with proper care will last me double that.
I can not say enough good things about Tankless water heaters ! It is tucked behind the refrigerator and you would never know its there !
Being in the sub-tropics, we shower 2 times a day (water is from my 24v desalination unit that converts sea water into fresh water), as well as cook with LPG on my 54 foot boat. A 20 pound tai lasts us nearly 3 months for cooking and heating water.