Mathematical modelling and performance evaluation of a hybrid photovoltaic-thermoelectric system

A combination of photovoltaic (PV) and thermoelectric (TE), named as the photovoltaic-thermoelectric (PV-TE) hybrid system, is a promising method to effectively broaden the use of solar spectrum and increase the total power output. In this study, a mathematical model of the hybrid PV-TE system is developed based on thermal resistance theory for PV panel, heat sink, and thermoelectric generator (TEG). The electric and thermal performance of the hybrid system is then obtained by iterative calculating temperature, which is a link of electricity and heat coupling generation of the system. Meanwhile, various heat losses and weather conditions are taken into account during the numerical simulation, and the PV alone is taken as a reference for comparison. For the hybrid system, the effects of concentration ratio and temperature coefficient on system performance are also investigated. Results indicate that higher concentration ratio and smaller temperature coefficient of PV cells are ideal for designing the PV-TE hybrid system. Moreover, a sensitivity analysis is carried out on the thermal resistance of each part in the hybrid system and relevant performance parameters are studied. It is found that the cooling system, i.e. heat sink, dominates thermal resistance of the hybrid system, indicating that reducing thermal resistance of the cooling system is the most effective way to improve the efficiency of the hybrid system. Through employing optimum parameters, operation performance of the hybrid system has been evaluated under two typical weather conditions, and results show that the PV-TE still produces 1.24-2.85% higher electricity than PV alone although the cell temperature in PV-TE is higher. If the material's physical property is improved, the electrical benefits of the combining PV and TE will be enhanced and it will be promising for application in the future.