Energy use, this is from the energyguide yellow tag. The thing about this number is it is some kind of average of how they think people wash, how many heavy duty cycles, regular cycles, etc.... so can only give us an idea.
They say 168kWh for 416 loads of laundry. This is .4 kWh per load, on average, using their data and assumptions. For me, this would be worth the energy cost, even off my batteries, compared to hand washing, at least for realy dirty or bulky items ( sheets, towels, pants, shirts...). I am also intrigued by washers converted to run off pedal power, but that kind of set up takes up a lot of dedicated space. I have neck issues, and arm/shoulder powered washing is not what I can do ( so, no James washer, etc....)
So, for my house as an example, they say to take 5 hours of sun a day as average over the year, that would make 5x2.5kW=15kWh a day energy budget, so a load a day would be less than 3% of that energy budget. This is a bit more than a standard sized kenmore elite front loader ( which is rated at 95kWh a year for 416 loads).
My take aways, washing clothes, if using cold water and no dryer is a very low energy convenience. If you have the room, a larger washer is more energy efficient. If you dont have space or need one you can roll out of a closet or put in your RV, or pick up and move, the small portables like this are a good option that works well, and the energy use is still very low. Start up surge of any motor needs to be taken into account if using a small solar/inverter set up.