Effect of materials and design on PV cracking under mechanical loading

As the PV industry considers new cell and module designs of lower cost, the reliability and durability become a major issue. Hence, it is important to evaluate the influencing factors on the mechanical strength of solar cells. In this work, a 3D FE model is used to investigate the stresses which are generated from mechanical loading and the XFEM to predict the crack initiation and propagation. Several aspects related to geometric configurations and PV module material properties are investigated. A material imperfection in the form of a locally reduced Elastic modulus by 10% resulted in a decrease of failure load by 70%. PV modules with Si thicknesses of 0.1, 0.15 and 0.2 mm are expected to crack under a uniform mechanical loading of 5400 Pa at different loads. In the case of isotropic Silicon of 0.1 mm thickness, the fracture takes place at a load lower than 2400 Pa. PV modules modelled with isotropic silicon were found to fail at a lower load, approximately by 12%, compared to those with anisotropic silicon. Finally, the study showed that half-cell PV modules experience reduced mechanical stresses, cracking initiates in higher load and the crack propagation is arrested at the boundary of the cell.