A review on solar photovoltaic-powered thermoelectric coolers, performance enhancements, and recent advances

The average global temperature has increased by approximately 0.7 degrees C since the last century. If the current trend continues, the temperature may further increase by 1.4 - 4.5 degrees C until 2100. It is estimated that air-conditioning and refrigeration systems contribute about 15% of world electrical energy demand. The rapid depletion of non-renewable resources such as fossil fuels and the associated emissions lead to the development of alternative solutions which employ renewable energy resources for refrigeration. The conventional vapour compression (VC) and vapour absorption (or adsorption) (VA) refrigeration systems usually rely on fossil fuels for their operation which ultimately leads to large amount of CO2 emissions. Thermoelectric (TE) refrigeration systems working on the principle of Peltier effect are an alternative for the conventional systems. The thermoelectric refrigerators will not produce any noise and vibration due to the absence of any moving parts. They are refrigerant-free as electrons act as heat carriers. The greatest advantage of a TE system is that it can directly be powered by solar photovoltaic (PVs) since they give a DC output. The main drawback of thermoelectric refrigeration system is their low coefficient of performance (COP). The COP of a thermoelectric cooler (TEC) operating with a temperature difference of 20 degrees C is about 0.5. The improvement of heat transfer at the hot side of the cooler is a key aspect for a better COP. A good thermoelectric material should possess high Seebeck coefficient, low-thermal conductivity, and high electrical conductivity. Since these three are interrelated, these parameters must be optimized. It is important to reduce the electric contact and thermal resistances and get an optimized configuration of thermoelectric cooler. The recent developments in material science has enabled the usage of better thermoelectric materials with a positive Thomson coefficient to produce a better cooling performance. The total efficiency of a TEC powered by solar cell is the product of PV system efficiency and the COP of the cooler. Therefore, the enhancement of PV system efficiency and the selection of materials with better thermoelectric performance are important in the design of solar-powered thermoelectric cooler. The performance of solar cell-powered TEC depends on solar insolation which varies with weather, climate, and geographic location. Due to the variation in insolation and unavailability of solar power in the night, a battery must be used to store the energy. This paper presents a comprehensive review about the thermoelectric coolers and the dependance of performance of TECs on various operating and design parameters. The results reported for the performance improvement of solar PV-powered thermoelectric coolers were critically analysed.