Fridge0 is a design for an offgrid, solar powered fridge, with no battery bank. Using an inexpensive chest freezer with a few modifications, the fridge retains cold overnight and through rainy periods.
Fridge0 consists of a standard chest freezer, an added thermal mass, an inverter, and computer control. It ties into the typical offfgrid system of a solar charge controller, battery bank, and photovoltaic panels to maintain a safe temperature range.
The battery bank is a large part of the cost of a typical offgrid fridge installation. It needs to be sized to run the fridge overnight, as well as for several days of poor weather. Cheaper batteries only last 3-5 years, and longer lasting batteries are correspondingly expensive; either way a battery bank for an offgrid fridge is extremely expensive over the lifetime of the friddge.
By storing solar power in the form of cold, fridge0 avoids the battery bank expense and environmental footprint. The only battery power fridge0 needs is enough to turn it off cleanly when the solar panels stop producing -- a few minutes of power instead of days -- and a small amount for its computer control.
There are offgrid fridges produced by several manufacturers, which are designed for 12v solar power, but these still may need a battery bank, and are much more expensive than conventional equipment due to being very well insulated using features like vacuum bottles. These offgrid fridges were designed when solar panels were much more expensive than they are today.
With modern cheap and efficient solar panels, commercial offgrid fridges make less sense than they used to. A kilowatt of solar panels provides enough power to run a conventional fridge on even most cloudy days, and costs less than a commercial offgrid fridge.