I just read something very interesting in the Spring 2009 issue of the Permaculture Activist magazine, written by a guy in Australia who uses photo voltics.

The article is titled "A Fridge That Takes Only 0.1 kW a Day".

Fact: chest style freezers contain the cold due to their design. In upright freezers the cold air runs out like water every time the door is opened. So he wondered what would happen if he converted a Vestfrost SE255 chest freezer into a refrigerator.

He bought a $40 battery-powered thermostat equipped with digital temperature display and an internal 5A/240V latching relay. The latching relay consumes battery power only during actual switching so that the thermostat equipped with it is a true micro-power device and its two AAA batteries last for many months.

"Connection is really simple. The thermostat relay cuts the power to the freezer, much like a light switch cuts the power to a lamp. The thermistor (the temperature sensor) is placed inside the freezer at the end of a thin 2-wire flexible cable. I used the freezer drain hole to pass the thermistor cable inside the cooling compartment. An alternative is to insert it from the top via the chest door. If the thermistor is left near the bottom of the chest fridge -- the minimum fridge temperature is controlled by thermostat. If the thermistor is located near the top of the cooling compartment -- the thermostat will control the maximum temperature there. The best position for the thermistor is somewhere in the middle.

"It took me about 30 minutes to make all connections. The most time-consuming part was removing the thermistor from inside the thermostat (I cut it out from the circuit board using wire clippers) and soldering it at the end of a thin two-wire flexible cable. I protected the thermistor from moisture and mechanical damage using shrink-wrap tubing and a tiny bit of silicone.

"The external thermostat can be installed anywhere on the fridge or outside it. I decided to place it on the wall behind the fridge, so that the temperature display is easy to read at eye-level.

"I have also removed the interior light bulb, rated 15 watts, because I avoid using energy-wasting devices as a matter of principle. I will consider installing LED interior illumination if I find a reason for opening my fridge in the dark.

"I set the thermostat to +7ºC (46ºF) and switched on the AC power through an energy measurement gadget called Sparometer. After about two minutes my thermostat displaced +6.5ºC and the power to the freezer was cut off. The temperature continued to drop down to about +4ºC. I thought that there was something wrong with the digital display, because everything happened too quickly. I took another thermometer, and to my surprise, ti confirmed readings of the thermostat.

"... In the first 24 hours my new chest fridge took 103Wh (0.103kWh) of energy. About 30% of this energy was consumed during the initial power up and rearranging of the fridge content... The fridge interior temperature was kept between +4º and +7ºC. The fridge compressor was working only for about 90 seconds per hour. When the thermostat intervened-- the fridge consumed ZERO power. The only active part was a battery powered temperature display.

"Results of my experiment exceeded all my expectations. My chest fridge consumes as much energy in 24 hours as a 100W light bulb does in just an hour... I have never seen a fridge that was SO quiet. It only works 90 seconds or so every hour. At all other times it is perfectly quiet and consumes no power whatsoever."

He uses stacked basket to hold foods, placing the most frequently used foods in the top baskets that slide on the top edges of the fridge walls.