Favorite from Albert Einstein, "The difference between genius and stupidity is that genius has its limits"
Chris Carl wrote:A "simple" solution is rarely cheep or universally applicable, here's mine. I built my own top-opening refrigerator and freezer. They are solar powered, between them they consume about 40amp-hr/day, 12v, in Florida. OK, my application is different than in an 'earth berm', mine is on a sailboat. Both fridge and freezer are low volume, fridge about 3 cuft, freezer 1.8 cuft. They have been running non stop (despite 5 hurricanes) for about 10 years. Claim to fame ... 'I have never been without ice or cold beer', that works for me. The secret, "Engle, swing motor 12 volt compressors". I use one for the fridge and another for the freezer for built-in redundancy and better control. This system and the rest of the boat is powered with 500 watts of Kyocerra solar panels and 1000 amp-hr battery bank. It has worked flawlessly for 10 years. The power system also provides lights, fans, instruments, radio, SSB communication and occasional 'movie nights' with an inverter. I'll stop bragging and get back to the point; efficient refrigeration is achievable with a few sheets of petrochemical foam insulation and some kind of manufactured compressor/cold-plate. My fridg is insulated to about R-30 (5 inches of polyiso), the freezer to R-50 (7 inches of polyiso). So the walls are thick, the outside volume large and the inside volume small but it's been essentially free refrigeration. And you can do this!
"Engle" https://www.engelcoolers.com/ is an Australian company and only maker of the "swing motor" compressor, a particularly efficient little unit, uses about 3 amps at 12v when running. I used two "icebox conversion kits", with separate thermostats. These units can be located up to 8 feet from the box itself or installed underneath. My compressors are remote mounted but I have installed units under the insulated box too. (Disclaimer: I am a dealer for Engle, it got me better prices, no other affiliation)