Solar driven concentrated photovoltaic-thermoelectric hybrid system: Numerical analysis and optimization

Abstract

In this study, a theoretical model of a concentrated photovoltaic-thermoelectric hybrid system has been developed based on first and second laws of thermodynamics and analysed in MATALB. A numerical method has been exploited to determine the temperatures of photovoltaic module (PV) and hot and cold side of thermoelectric generator (TEG) by iteratively solving the energy balance equations. The proposed study takes into account the effects of hot and cold side thermal resistances, thermoelectric properties, fill factor, geometry of thermoelectric module, load resistance and electrical current on the performance of the hybrid system. The results show that the optimum value of ratio of TEG load resistance to TEG internal resistance, m for maximum power output and efficiency of thermoelectric module is higher than unity. The concentration ratio should also be optimized to achieve maximum PV power output. For the fixed leg length of 5 mm and CG value of 1 kW/m2, the optimum m corresponding to maximum power output and maximum efficiency of the hybrid system is 0.5. The maximum power output and efficiency of the hybrid system increase by 5% as compared to the corresponding values of concentrated PV system. Moreover, at higher concentration ratios, the contribution of thermoelectric power to the power output of hybrid system is higher. Further, for other parameters fixed, the optimum value of CG for maximum power output of the hybrid system is 5.5 kW/m2 and it is 14% higher than the corresponding power output of CPV system alone. This improvement in the performance of hybrid system is added by the thermoelectric generator module. The results of this analysis incorporating the electrical and thermal contact resistances of thermoelectric device, may be helpful to envisage the design of a real photovoltaic-thermoelectric hybrid system.