If one had a regular deep chest freezer with bottles of ice in it, several of these methods could be combined.

During regular times, the ice in the bottles could be kept cold the easy way, plug it in to the wall.

Once an issue happens, and you determine that it will be extended, you already have all that existing ice. Using the icemaker idea, either powered by solar/battery/generator, whatever could maintain the temp of a chest freezer indefinitely.

I do agree with Telsinhiker's numbers, a small dorm fridge could be kept running via the solar. Having used several dorm fridges, I have concerns about their temperature stability. They are very small, and every time you open the door, 1/2 the cold falls out.