G0310103 Thermal Deformation Analysis of Solar Cells Considering Thickness Effect of Silicon Wafer

Abstract

Transformation of conventional energy systems to renewable energy can limit the climate change to a safe level. Among the sources of renewable energy, solar energy is more convenient and easy to access. However, high cost of silicon wafer is a problem for photovoltaic solar cells. Therefore, manufacturers need to the development of solar cells made of thinner crystalline silicon wafer as a way to reduce costs. Silicon is brittle, and thinner silicon is easier to break due to residual stress induced during soldering process under high temperature. The solar cell conductive film (CF) can bonds the solar cell with metal ribbon at lower temperature than soldering. After the manufacturing process when the solar panel is subsequently exposed to sunlight for its operation, the temperature distribution redistributes the residual stress. Therefore, it is necessary to know how silicon wafers of different thicknesses are deformed for the two bonding materials, solder and CF in order to find out a reliable bonding option for thinner silicon. This study used the finite element method (FEM) to analyze the thermal deformation during the manufacturing and using processes of solar cells with different thicknesses of silicon wafer. It was found that varying the thickness of silicon wafer has long term effects on the deformation and residual stress. Sn-3.5Ag solder and CF were employed as the bonding interface to carry out a comparison of the thermal deformation characteristics.