Modelling and experimental investigations of microcracks in crystalline silicon photovoltaics: A review

In recent years, the scientific research into photovoltaic (PV) technology has focused on the failure modes in order to increase the PV reliability, durability and service lifetime. One of the predominant failure modes that appears in the crystalline silicon (c-Si) PV technology is the cell cracking that may damage the mechanical integrity of the PV module and hence, result in power loss due to the disconnected areas of the cell. Other forms of degradation may also be triggered such as potential induced degradation (PID) and hot spots. Therefore, the understanding of the cracking mechanism is of great importance. This paper 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. (C) 2019 Elsevier Ltd. All rights reserved.