Analysis of thermal response and electrical characterisation of triple-junction solar cells based on variable solar spectral irradiance and air mass

Abstract

This paper presents the effects of Air Mass (AM) on solar cell performance. This atmospheric parameter has a strong influence on the behaviour of high concentrating photovoltaic solar cells. As air mass increases, the Direct Normal Irradiance (DNI) decreases and resulting cell temperature (Tc) decrease. The objective of this work is to assess the effects of air mass (AM = 1–10D) on triple-Junction solar cells. A thermal model using a convergent iterative technique has been developed; the predicted convergent cell temperature is ≤80 °C for the range of parameters tested. The rate of heat loss by convective heat transfer from the cell is also considered for air mass values AM = 1.5, 4 and 8D. A Finite Element Method (FEM) model is developed in COMSOL Multiphysics in order to predict the temperature distribution on PV cells and the thermal behaviour of the receiver assembly. The proportion of the absorbed radiation not converted to electricity is converted to heat; also, heat from potential current mismatch resulting in an increase in cell temperature is taken into account. As the air mass increases, results show that the spectral attenuation has a significant effect on the thermal and electrical conversion efficiency of triple-junction solar cells. In addition, spectral change is one of the causes of the current mismatch in triple-junction cells. Thus, cell parameters such as short current density (Jsc), efficiency and output power are affected.