Analyzing life tests of CIS solar modules for degradation modeling

Generally, accelerated life tests of electronics devices have been completed in dark chambers where thin-film solar cells show high degradations which have never happened at exposure experiences. Light soak free decrease paths show two phases: a relative steeper logarithmic decrease followed by a gradual linear decrease. These two phases are analyzed in complicated 1,000h damp heat test paths of 151 commercial CIS modules, demonstrating that the high degradation of the linear phase consistently occurs when the logarithmic phase ends. Furthermore, observed degradation gradients are affected by not only cell characteristics, but also test readout interval times, which corrupts life estimations such as underestimation of life, existence of pseudo failures, and missing actual failures. Therefore the life tests of CIS/thin-film cells in dark chambers require the paradigmshift such as neglect for pseudo-degradation or adapt to new light soaking related acceleration metrics.