Numerical modelling of structural damage and cracking in crystalline silicon photovoltaics

Abstract

In recent years, scientific research into photovoltaic (PV) technology has focused on the failure modes in order to increase PV reliability, durability and service lifetime. One of the predominant failure modes that appears in the crystalline silicon (c-Si) PV technology is cell cracking which may damage the mechanical integrity of the PV module and hence, result in power loss due to the disconnected areas of the cell. Therefore, the understanding of the cracking mechanism is of great importance. This work presents the origins and factors that affect the cell cracks. Classification of cracks has been conducted as their characteristics determine the mechanical and electrical degradation of the PV module. Furthermore, experimental and numerical studies related to PV cracks on the scale of wafer, cell and PV module are analysed in detail. The results from the above investigations show that cracks do not always lead to a strong performance degradation and therefore the impact of cracks on the electrical characteristics of PV modules is still debatable. To investigate the stresses generated from mechanical loading and predict the crack initiation and propagation, a 3D FE model and an XFEM model are used, respectively. Several aspects related to geometric configurations and PV module material properties are investigated.