Performance analysis of photovoltaic-thermoelectric hybrid system with and without glass cover

This paper establishes a theoretical model for assessing the performance of glazed/unglazed photovoltaic-thermoelectric (PV-TE) hybrid system. To enhance the heat removal, nanofluid is served as heat sink. Firstly, a performance comparison between glazed and unglazed system is given. It is suggested that, under the condition of higher figure of merit Z and concentration ratio C, as well as enhanced transmissivity of glass cover, glazed system may be competitive or even superior to the unglazed one. Environmental effect such as wind velocity, is also a significant factor which may be ignored in the existing researches. Therefore, considering the coupling effect of wind velocity and nanofluid flow rate, the impacts of some key parameters on the system overall efficiency are examined in the following part. It is found for certain TE modules, a higher figure of merit Z may still cause a decrease in the system overall efficiency resulting from the different parameter values, that is, Seebeck coefficient s, electrical resistivity ρ and thermal conductivity λ. When thermoelectric efficiency ηTE reaches maximum, the obtained optimal load resistance Rl is larger than that corresponding to maximum overall efficiency η. With varying wind velocity, the maximum overall efficiency could achieve at maximum or minimum wind velocity, corresponding to Z = 0.0021 K−1 and Z = 0.0085 K−1 conditions, respectively. In addition, nanofluid shows better performance than water.