Numerical Simulation of the Evolution of Stress in Solar Cells During the Entire Manufacturing Cycle of a Conventional Silicon Wafer Based Photovoltaic Laminate

Abstract

A significant amount of failure and fracture in solar cells have been observed during the soldering and lamination of a photovoltaic (PV) module. This implies that high residual stresses are developed in the cells. In this paper, the evolution of stresses in solar cells throughout the manufacturing cycle of a conventional PV laminate is simulated in a sequential step-by-step manner such that the residual stresses at the end of one step is brought forward to the next. By analyzing the principal stresses generated in the cells, the critical instances in the manufacturing cycle can be identified. The accumulated final residual stresses in the PV laminate are determined, which include the postsoldering, lamination, and postlamination thermal stresses because of the coefficient of thermal expansion mismatch between the laminate constituent materials. In addition, stresses in the cells during the pressure-ramping step of the lamination process are determined and found to be the most critical in the entire PV laminate manufacturing cycle. The effect of cell thickness on the evolution of stresses in the cells throughout the manufacturing cycle of a conventional PV laminate are also investigated.