I have looked at off grid in Texas, and unless a house is buried deep within the earth, or can take advantage of some natural feature (a nearby water turbine on a stream), keeping the place cooled in the summer is virtually impossible without mains power.
For everything else, a house can run from propane for heating, the gas dryer, water heater, and even the refrigerator. Electric for the smaller appliances can easily be handled by a set of panels, battery bank, inverter, and charge controller. However, HVAC needs will tie a residence to the grid.
I wonder if someone can scale the mechanism up for an RV fridge and make a propane based water chiller. This way, power needs would be a lot less (mainly to move air through a heat exchanger), as the propane would be the energy source for the refrigerator. Bonus points in using the Einstein cycle where that uses ammonia, butane, and water.
If HVAC needs can be moved from the grid, that will help immensely, especially in warmer states.