Although I am an "Off-Grid" person. I still love all the comforts and luxuries of automatic technology in my home. On the boat, I am limited with space for a solar water heater tank (100L to 200L). I am using a tankless water heater that uses LPG.
As long as the oil companies are around, we will always have LPG (Liquid Propane Gas). This allows me to stay off the grid by using portable tanks to heat my water (and cook with).
I realise the land homes can mount a tankless water heater on the outside of a structure, and not worry about venting, and can use "D" size batteries for ignition, etc. I have had a tankless water heater made that has the exhaust blower and ignition system that is 24v and is directly powered from my battery bank (that my solar panels charge). I am able to install the tankless water heater inside, and mounted behind the refrigerator to save a lot of space.
Those that do not know how the tankless water heater works, here is an example...[You must be registered and logged in to see this image.]
Here is the unit I had made. It will heat 12 litre of water per minute... more then enough to take a shower, and wash dishes at the same time. Keep in mind that the fresh water pump is 24v as well, and will pump 16L per minute at 40 PSI.[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]
I am very happy with this unit, and encourage others to do the same !