The use of solar heat for product cooling has been known since the time of ancient Egypt, but the cooling principle used by Egyptians is still popular in some regions in Africa and Asia. In modern interpretation, this principle of evaporative cooling is called Pot-in-Pot. Construction of such a refrigerator is quite simple. Two clay pots are located one inside of other. The inner pot is made of baked clay, which does not allow moisture, external from unbaked. The space between these two pots is filled with sand, which must be constantly moistened. Moisture evaporating through the wall of the external pot takes away heat and cools the inner pot.

Illustration  1: “Pot-in-pot” Refrigerator

Even such a simple device, in an African heat can support the temperature of about 5 ° C. A much more “advanced” device for a refrigerator working on solar energy has been offered by French engineer Auguste Mouchot (1825-1911). Perhaps, he was the first who really thought to use of solar energy in everyday life and in industry. At the Paris Exhibition in 1878, he introduced a “freezer” working on solar energy. The principle of the device was as follows: with the help of a parabolic mirror, the sun’s rays focused on the boiler with water, and the steam generated by heating runs the compressor unit with which the freezer worked. Thus, the public seemed to turn the water into ice with the help of heat from the Sun.

Illustration  2: “Solar freezer” by Auguste Mouchot at the Paris

After electrification all over the world, all these ideas were almost forgotten, and a refrigerator working on electricity confidently entered our everyday life and industry. And in fact, today in most countries the presence of electricity at homes is taken for granted, and the energy supplied by the power grid is infinite, nobody think that it is better to turn off an unnecessary light lamp or computer when it does not work.

Illustration 3: Cold room by solar panel solar panels

But, at the beginning of the 21st century, people finally thought about the problem of Global Warming and the renewable energy sources becomes actual. Developed countries began to invest in solar energy technologies and  solar panels since 2010 became available to a wide range of consumers. It should be noted that the idea of a refrigerator powered by electricity produced by solar panels is absolutely “energy balanced” because we need cooling on hot, sunny days, and on such days we have the maximum energy output from solar batteries. And given that in our lives there are natural disasters in which many developing countries lack electricity, and even in developed countries, electricity becomes unavailable everywhere, we can conclude that a refrigerator working on solar energy will be in demand in many cases.

It should be noted that the calculation of the necessary power of solar panels and the capacity of storage batteries for powering the refrigerator at night and on cloudy days depends not only on Insolation at given  location, but also on the thermal conductivity of the refrigerator walls, and on the type and volume of products stored in the refrigerator. Our company set a goal to develop an optimal Coldroom designed for storing agricultural products in the territory of Armenia. The prototype of such camera is already assembled and is in the testing phase.