Efficient water heater options?

We're trying to figure out what our solar needs will be for two off-grid yurts we'll be building and living in this spring in central New York. Someone mentioned that, generally speaking, using electricity to heat things (e.g., water) is pretty inefficient and takes a ton of energy. I was looking at some electric tankless on-demand water heaters that do seem pretty high in their energy needs (e.g., ranging from 9 to 27kW of electricity). Do people have other recommendations for heating water? The bit I read about rocket mass water heaters makes it seem out of my reach...

I've seen many off-grid people using tankless propane water heaters but we have an aversion to propane (because it's a fossil fuel and just nervous about the safety of it for indoor use in terms of fumes and flammability) – though maybe propane is the way to go....

Any suggestions? Thanks!

How about an electric tank water heater?  The "on demand" aspect of that other style is what draws all the current.  I'd imagine you could keep a small (5-15 gallon) water heater hot with solar panels.  You might also be advised to change the heat element over to DC and directly heat it from the panels instead of inverting and converting to and from AC.

Most Heat pump water heater can be set up for 120 volts with a 15 amp breaker (you will need to research them).  You can also set them up with the 220 volt heating elements when larger amounts of hot water are needed.  When using them with only the heat pump (120) they are slow, run on 120 volts, put out cold air into the room, and dehumidify the air.
If you have a very cheap heat source like a rocket mass heater then the bit of heat the heat pump will use will not be noticed.

Tankless hot water heaters have issues unless you have great water.  Even with the best water you will need maintenance every 6 months to keep them working efficiently.  If you get a tankless water heater that is rated at 7.5 GPM at a 35° temp rise, but your winter time water temp is 52* their is a good chance you will be let down.

These are great suggestions - thanks! Neither are options I had been considering, but I will now...!

I too would like to find a better way for hot water and implement it, but currently I'm using the under $200 USD Ecotemp L5 hooked up to a farm hydrant running municipal water. I drain the unit and the hose leading to it after every use in the winter to prevent freezing.

The first one I purchased stopped igniting after only 2 months, but I got a free replacement plan from Camping World and this one has been good for 8 or more months now...they let you keep the old one so it's most likely a minor issue that I will eventually get around to tinkering with.

I understand wanting to stay away from these, as without a propane supply they are useless, but so far this has been a fast, cheap, easy way to get instant hot water for dishes and showers in my home made bath house. I would suggest it for use if you have nothing at the moment, while you research and plan for a more environmentally friendly system.

There are other models which require less water pressure, or rely on their own small pump, if high pressure water supply is not available.

I think it's efficient because the thing just sits there dormant (it uses D batteries for the igniter) when not in use...which for my lifestyle sometimes is days at a time - where a conventional water heater would be wasting a lot of energy!

I regards to issues with water quality, I have researched a bit about scale buildup and am probably due for a flushing of some sort...figures I have waited until winter is already here before attempting that :)

Oops I forgot to mention that it has flow rate and heat power adjust knobs, and in the middle of winter where ambient air temps are 10*F the burner all the way up and flow rate all the way down still does provide a suitable (for me) amount of hot (not just warm) water for a shower.

I didn't take actual water temperature readings but when it starts to get real cold here again maybe I could do a little test...I remember last winter the bath house being delightfully steamy inside when there was snow on the ground and cold roaring wind - set aside my personal negativity for buying propane and a store bought water heating device, I am soooo happy and grateful for the ability and feeling it provides me while I work on advancing the property and structures here on a budget and time frame.

That sounds like a good option, too! Thanks, Cole. I think the hardest part for me would be having to drain it after every use in the winter...

In Bulgaria a lot of the older houses have wood fired hot water heaters, which are still available for sale and relatively inexpensive. The tank needs to be properly vented so the steam doesn't create an explosion risk, but they seem to work well and also heat the bathroom up nicely before a shower. I'm not sure whether such things are available in the US, but if they are, it could be an option provided you have wood available.

How do you plan on heating your home. I would use that to heat some water too. It could be as simple as a pot on a stove.

If you are grid-tied. Then I recommend using the tankless water heater, https://www.homedepot.com/p/Rheem-Performance-18-kW-Self-Modulating-3-51-GPM-Tankless-Electric-Water-Heater-RETEX-18/300800620.

If you are off-grid. I just don't see you having a 36,000WHr+ battery bank and 18,000W inverter just laying around to power you 18,000W water heater