Solar-powered refrigerators are able to keep perishable goods such as meat and dairy cool in hot climates, and are used to keep much needed vaccines at their appropriate temperature to avoid spoilage.
There is environmental concern regarding conventional refrigeration technologies including contribution to ozone layer depletion and global warming. Refrigerators which contain ozone depleting and global warming substances such as chlorofluorocarbons (CFCs), in their insulation foam or their refrigerant cycle, are the most harmful. After CFCs were banned in the 1980s, they were replaced with substances such as hydrochlorofluorocarbons (HCFCs), which are ozone-depleting substances and hydrofluorocarbons (HFCs). Both are environmentally destructive as potential global warming chemicals. If a conventional refrigerator is inefficient or used inefficiently, it will also contribute more to global warming than a highly efficient refrigerator. The use of solar energy to power refrigeration strives to minimize the negative impacts refrigerators have on the environment.
In 1878, at the Universal Exhibition in Paris, Augustin Mouchot displayed Mouchot's engine and won a Gold Medal in Class 54 for his works, most notably the production of ice using concentrated solar heat.
"In developed countries, plug-in refrigerators with backup generators store vaccines safely, but in developing countries, where electricity supplies can be unreliable, alternative refrigeration technologies are required". Solar fridges were introduced in the developing world to cut down on the use of kerosene or gas-powered absorption refrigerated coolers which are the most common alternatives. They are used for both vaccine storage and household applications in areas without reliable electrical supply because they have poor or no grid electricity at all. They burn a liter of kerosene per day therefore requiring a constant supply of fuel which is costly and smelly, and are responsible for the production of large amounts of carbon dioxide. They can also be difficult to adjust which can result in the freezing of medicine. The use of Kerosene as a fuel is now widely discouraged for three reasons: Recurrent cost of fuel, difficulty of maintaining accurate temperature and risk of causing fires.
Traditionally solar-powered refrigerators and vaccine coolers use a combination of solar panels and lead batteries to store energy for cloudy days and at night in the absence of sunlight to keep their contents cool. These fridges are expensive and require heavy lead-acid batteries which tend to deteriorate, especially in hot climates, or are misused for other purposes. In addition, the batteries require maintenance, must be replaced approximately every three years, and must be disposed of as hazardous wastes possibly resulting in lead pollution. These problems and the resulting higher costs have been an obstacle for the use of solar powered refrigerators in developing areas.
In the mid-1990s NASA JSC began work on a solar powered refrigerator that used phase change material rather than battery to store "thermal energy" rather than "chemical energy." The resulting technology has been commercialized and is being used for storing food products and vaccines.
- UNEP 2005. SolarChill: the vaccine cooler powered by nature. Paris, France: UNEP Division of Technology, Industry and Economics, 1-16. Retrieved January 29, 2005
- Pedersen, PH. Maté J. 2006. SolarChill vaccine cooler and refrigerator: a breakthrough technology. Industria Formazione. Special International Issue: Refrigeration and Air Conditioning.No. 300, Suppl. 1(No. 6–2006):17–19
- Burton, A. 2007. Solar Thrill: Using the sun to cool vaccines. Environmental Health Perspectives. 115(4): 208–211
- Pedersen, PH., Poulsen, S., Katic, I. (n.d.) SolarChill—a solar PV refrigerator without battery. Danish Technological Institute. Taastrup, Denmark: Solar Energy Centre, 1–4.