We are planning to install a solar system even though its expensive. I don’t want to spend 2-4 years boiling clothes in a pot over a fire in the backyard. :-)
I've done that for several years at a time.
The first thing that goes is your sense of smell.
When you find yourself sweeping the dirt out of the bed-sheets with a broom (and needing a dust pan), you get serious about mechanical washing.
/johnny