Modeling Thermal Fatigue in CPV Cell Assemblies

A finite-element (FEM) model has been created to quantify the thermal fatigue damage of the concentrating photovoltaic (CPV) die attach. Simulations are used to compare the results of empirical thermal fatigue equations that have originally been developed for accelerated chamber cycling. While the empirical equations show promise when extrapolated to the lower temperature cycles characteristic of weather-induced temperature changes in the CPV die attach, it is demonstrated that their damage does not accumulate linearly: The damage that a particular cycle contributes depends on the preceding cycles. Direct comparison of the FEM with empirical methods and calculation of equivalent times for standard accelerated test sequences were made using CPV cell temperature histories.