Some ways to run a fridge on solar energy

Checkthisout said:

Weird. Using another calculator it says 850 btuh is all that's needed for a 16cuf box. *sigh*

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That's just an estimate, of course. Your mileage will vary. Maybe by a lot.

Larger fridges generally use less BTU per cu ft thanks to scaling math. Doubling the length, width and height doubles the door seal length thus doubles warm air infiltration. It quadruples wall surface area through which heat transfers. So you've got 2x of one type of heating and 4x of another. And it's often more like 3x through the walls because larger fridges tend to have thicker/better wall insulation. Meanwhile, that 2-3x higher BTU/hr buys you 8x as many cubic feet!

The other big variables are temperatures inside vs. outside the fridge and how often you put warm items in. Keep the fridge in a cool room (e.g. basement). Vent warm air coming off the (clean) coils up and away from the fridge. Add insulation to the outside walls. Keep it as full as possible while still allowing air to circulate inside, and return food/milk/etc. quickly before it has time to warm up. Push these measures to extremes and that little DC compressor might even run a full size fridge.

I have a couple of small compressor fridge cooler's that I use for camping. They are both extremely efficient, if a little small for the OP's purposes.
The smaller of the two pulls 20-35 watts when running. When set to maintain <38 degrees, the 24 hour power draw is 135Wh. A 100 watt panel and a small battery will keep it running for a very long time for sure. The larger of the two draws ~220Wh/24hrs. So, at least at my scale, off-grid refrigeration is no problem at all. refrigerant for the smaller unit is r134a. test conditions were 75-80 degrees. The unit was 1/2 full of water jugs.