Each device powered by any energy source is characterized by a parameter called energy efficiency, which determines the extent to which in a given process the energy supplied in it is converted into output energy. A thermoelectric cooling cell is composed of a layer of semiconductors sandwiched between two ceramic electrodes in a similar way to the electrodes separated by a dielectric, which are a simple electrical capacitor. Peltier cells It is used in various applications, such as cooling processors in computers and as thermoelectric voltage sources. The Peltier modules offered by the Botland store operate on the principle of a small heat pump. By connecting a DC power source to the module cladding, heat is transferred from one cladding to another. This creates a temperature difference. Peltier cells are often used e.g. in industrial applications, portable fridge-freezers, electromedical equipment, as well as in measuring instruments.