Cold storage


 * 1) Leave buckets of water outside in the winter long enough for them to freeze solid
 * 2) Bring these inside an insulated room. This can be sand insulated, it can be underground, whatever, doesn't matter.
 * 3) During summer, the temperature will remain cool enough to refrigerator goods there. You also have a source of ice and cold water.

See how it was done in older days at https://en.wikipedia.org/wiki/Ice_house_(building)