SPLTRAK Abstract Submission
Lamination Process Induced Residual Stress in Glass-Glass vs. Glass-Backsheet Modules
Farhan Rahman1, Ian M. Slauch2, Rico Meier2, Jared Tracy3, Elizabeth C. Palmiotti1, Mariana I. Bertoni2, James Y. Hartley1
1Sandia National Laboratories, Albuquerque, NM, United States
/2Fulton School of Engineering, Arizona State University, Tempe, AZ, United States
/3DuPont Photovoltaic and Advanced Materials, Wilmington, DE, United States

Manufacturing process induces residual stress which can cause immediate or delayed cell breakage. Therefore, to reduce the levelized cost of energy for photovoltaic (PV) modules, it is important to analyze the effect of manufacturing processes on residual cell stress development. In present study, Finite element analysis (FEA) was performed to investigate the effects of photovoltaic module architecture: glass-glass (GG) or glass-backsheet (GB) on residual cell stress. During PV module manufacturing, the soldering of interconnects and lamination impart residual stresses onto the cell. However, for both module configurations the stress states at the beginning of the lamination process are same. FEA was performed using a high-fidelity mesh, to simulate the cooling of the heated encapsulant during lamination. Plasticity of solder and ribbons as well as viscoelasticity of encapsulant material were considered in the simulation. Higher stress in the GG configuration in comparison to the GB configuration was found. In GG, the maximum cell stress was at the front edge of the top ribbon while for GB it was along the ribbon footprint (side-edge of interconnect) on the wafer’s back-side (backsheet side). The performance of the different module configurations and the locations of peak stresses from current study agreed qualitatively with cell stress values obtained earlier using X-ray Topography (XRT) experiments. Separate soldering simulation indicated lamination step to be dominant in imparting residual stress during manufacturing. To perform a quantitative comparison between FEA and XRT results, the post-soldering stress values will be incorporated as initial condition for lamination simulation in future research.