Reliability-driven design optimization of si solar module under thermal cycling

The lifetime of solar modules is not only a reliability measure but also an important factor in increasing the competitiveness of the modules against other power generation technologies. The advancement of module technology has enabled an increase in the power lifetime warranty of Si solar modules, which is currently 25 years and is expected to increase further. To enhance the lifetime of the Si solar module under thermal cycling, numerical analysis, optimization, and experimental validation were conducted on module design. The strain energy density on the solder layer was identified as a critical measure of the reliability in thermal cycling. The solar module was numerically modeled, including the viscosity of ethylenevinyl acetate and solder layers. A series of sensitivity studies using the model revealed that the thicknesses of Cu and Si should be reduced to enhance the lifetime under thermal cycling conditions. The lifetime of the reliability-enhanced design is expected to increase by 181 %, or in the range of 156 to 209 %, under thermal cycling environments such as daily thermal fatigue in the desert. An experimental validation confirmed the design optimization.