Life prediction of HCPV under thermal cycling test condition

Abstract

High-concentration photovoltaic (HCPV) module is subject to larger thermal stress due to its more severe temperature fluctuation in real operating conditions. In the thermal cycling test, excessive thermal stress might occur at the peripheral solder layer. For the large area bonding structure, thermal-induced stress is the main cause for cracks. Crack growth is expected to start from the edges of the solder layer and progress to the center. The shrinkage of the bonding area increases the junction temperature of solar cells and reduces the energy-conversion efficiency of the HCPV module. In this study, the stress/strain behavior of the HCPV module under thermal cycling test is analyzed using finite element analysis software, ANSYS®. Results indicate that the von Mises creep strain distribution at the solder layer’s edge is independent of the package’s dimensions. The lifetime of HCPV with uniform solder layer could be predicted by assuming that the crack propagation rate is constant during solder layer degradation. Furthermore, lifetime of tilted HCPV module could be predicted by compensating the variation of thickness of solder layer during crack propagation.