Transient carrier recombination dynamics in potential‐induced degradation p‐type single‐crystalline Si photovoltaic modules

Abstract

In this study, we investigated the recombination dynamics of minority carriers through the decay profile analysis of transient diffuse reflectance spectroscopy (TDRS) for fresh and potential‐induced degradation (PID) modules. The PID‐affected region in terms of the degradation degree on the modules was firstly localized using conventional methods such as electroluminescence (EL) and lock‐in thermal images. The photogenerated carrier density and carrier lifetime were different in photovoltaic (PV) modules in fresh and PID modes. It was found that the dominant recombination involved the carrier transition via shallow trap states. The distribution of the trap states, however, was extended from the surface to the bulk of the solar cell due to Na ions–decorated defects. The behaviors of the carrier dynamics near the surface and bulk were very different, as inferred from the two different pump wavelengths of 532 and 1064 nm, respectively.

Effective minority carrier lifetime as an indicator for potential-induced degradation in p-type single-crystalline silicon photovoltaic modules

“…Transient absorption spectroscopy is also possible to investigate the carrier dynamics even for the PID-affected PV modules, in detail. 42,43) But such measurement system limits the sample size which is much smaller than the conventional PV modules and consumes a long time to finish the measurement, indicating conventional PV modules cannot be applied to such measurement to investigate the carrier's behavior in the PV modules after PID. Our proposed method in this work can finish a measurement in a second in one point, apply for large size modules, and become a nondestructive outdoor inspection to detect PID deterioration since μ-PCD method can be a portable system, indicating that it can open a new door for the investigation of the mechanism of PID phenomenon by focusing on the excess minority carrier profile.…”