I'm hoping that you will expound at length on your gravity motor. Not in this part of the forum of course, that's for a different heading entirely.
I live in TN and can see how you might want an off-grid option. We have some very rugged, very rural parts a mere half-hour's drive away from metro areas, and running power to them could get very expensive.
Humans got by almost entirely without refrigeration a mere 100 years ago, so what you're trying to achieve isn't too far a reach. It WILL require a significant expenditure of time and effort on your part however, which is almost entirely what the refrigerator supplants in its everyday function, though people don't usually realize it.
Then again, people used to die of dysentery and that doesn't happen that much anymore in the industrialized world.
If off-grid living is your goal you may still want refrigeration, if only for the occasional cold drink. To that end you could achieve a lot with a couple of solar panels and a direct-driven DC compressor in a homemade icebox.
One of
these little fellows could meet your modest refrigeration needs nicely. They're designed to take 24v DC directly, so I think you could run them straight off a pair of solar panels. Build up your coils into a homebrew, heavily insulated cabinet and you would be good to go.