Note that many 'dwellers choose to use no refrigeration at all.
Tips to make cooler use more effective and simple:
A refrigerator (refer or reefer) is used to keep items at a given cool temperature, typically ⇐40F.
Refrigerators give off heat and must be ventilated; ensure any vents exhaust into open area. Cooling performance may be enhanced by adding fans to move more air across the condenser2) and dusting components regularly.3) Cold retention can be enhanced by adding insulation in the form of foam sheets or insulative covers made for the cooler.
Front loading or “Upright” refrigerators are square or tall rectangles shaped like residential refrigerators. They stand up and have a door that opens off the side.
Top loading refrigerators are usually low rectangles shaped like insulated coolers.
Absorption (ie, propane-powered ammonia cycle) fridges were popular in RVs because they used minimal power to run the ignitor, control board, fans if any. This type of fridge had to to be quite level so the ammonia cycle cooling would work by gravity; there is no pump.5) Using one out of level could damage the $$$ cooling unit.
These fridges are often called three way fridges because they run on propane in the field, provide heat for the absorption cycle from 12v while driving, and from shore power when available. The fridges are very efficient (both propane and 12v controls) on propane, but use a great deal of power to run off electricity.
Absorption units are rare in vandwelling setups due to size, expense, and need for exterior venting.
Over the last few years RV refrigerators have been going to 12v or, more commonly, 110v residential style units.
12v compressor refrigerators become the standard way to chill food in solar-equipped vans. The main types of compressor fridges common in 'dwelling setups are:
Note that using a compressor fridge for refrigeration vs. freezing can have vastly different power requirements:
“I use a pair of 65 qt Whynter units, one as a fridge, one a freezer. The freezer uses somewhere around 4 to 5 times the power that the fridge uses. Keeping the fridge at 40F is fairly easy, keeping the same unit at 0F is another story.” – Almost There22)
Secessus describes the interior size of the Alpicool 15L (flat lid) version:
I store leftovers in pint and quart mason jars, which stand up fine in the [Alpicool] 15L. Longneck beers are slightly too tall. Since glass is heavy and harder to compact for trash removal I buy beer in cans anyhow. 16oz tallboys do fit. ←- the info discerning gentlemen need to know24)
Some have reported good results with inexpensive “dorm” refrigerators, especially when external insulation is added.
Peltier cooling doesn't get used much in solar setups because it uses a lot of power and does so 100% of the time. A typical Peltier cooler might run 4-5A continuously whereas a compressor cooler might run 5A 30% of the time and turn off the rest of the time. The 100% duty cycle issue can be alleviated by wiring in a 12v thermostat.25)
This kind of device cools to ~30-40F below ambient, which may not be a problem if the ambient is 80F or less. For best results avoid putting hot or even warmer-than-ambient items in the cooler. Use a fan on the item until it is room temp before placing in cooler.
Most lack thermostats and so can accidentally freeze food if ambient temps are low enough.
Read the manual before purchase to see how long it can be run at a stretch; fans are a common failure point when run 24/7.
In low humidity areas with a significant day/night temperature differential you may be able to cool or even freeze cooler packs and water bottles. Leave them outside overnight and put them back in the cooler in the morning.