Series of detail comparison and optimization of thermoelectric element geometry considering the PV effect

This study investigates the optimum geometry for maximum efficiency of a hybrid PV-TE uni-couple using Finite Element Method. COMSOL Multiphysics is used to solve the 3-Dimensional heat transfer equations considering thermoelectric materials with temperature dependent properties. Two types of thermoelectric element geometry area ratios are considered for the range 0.5≤RA≤2 and 0.5≤RS≤2. Nine different geometric configurations are analysed for two different PV cells. Effects of thermoelectric generator (TEG) geometric parameters, solar irradiation and concentration ratio on the hybrid system efficiency are presented. The results show that a hybrid PV-TE system will perform better with symmetrical TEG geometry (RA=RS=1) if a PV temperature coefficient of 0.004/K (Cell B) is used. This is different from the optimum geometry for a TEG only system. However, the optimum geometry of the TEG in a hybrid system will be the same as that of a TEG only system (dissymmetrical i.e. RA=RS≠1) if a PV temperature coefficient of 0.001/K (Cell A) is used. The overall efficiency and TE temperature difference show a decreasing trend as thermoelectric element length and area increase respectively no matter the configuration or temperature coefficient value used. Results obtained from this research would influence hybrid PV-TE system design for obtaining maximum conversion efficiency.