Performance analyses and economic evaluation of a hybrid thermoelectric solar water heater

Abstract

Performance and economic analyses of a hybrid thermoelectric (TE) solar water heater have been studied. The hybrid TE solar water heater was composed of transparent glass, air gap, an absorber plate, TE modules, water-cooled heat sinks, and storage water tank. The incident solar radiation heats up the absorber plate creating a temperature difference between the TE modules that generate a direct current. Only a small part of the absorbed solar radiation is converted to electricity, while the rest increases the temperature of the absorber plate. The water flows through each heat sink located under the TE modules to gain heat. The heated water then flows to the upper section of the absorber plate where it receives additional heating from the absorber plate. Improvements to the thermal and overall efficiency of the system can be achieved by the use of the double-pass collector system and TE technology. The experiment shows that the thermal and overall efficiencies increase as the water flowrate increases. The maximum and overall efficiencies were 74.9 per cent and 77.3 per cent, respectively, at the water flowrate of 0.33 kg/s. Meanwhile, the electrical-power output and the electrical-power generation efficiency depended on the temperature difference between the hot and cold sides of the TE modules. At a temperature difference of 27.1 °C, the unit achieved a power output of 3.6 W and the electrical-power generation efficiency of 0.87 per cent. Moreover, economic analysis indicates that the payback period of the hybrid TE solar water heater operating at the water flowrate of 0.33 kg/s is shorter and yields a higher internal rate of return.