Effect of temperature and pre-annealing on the potential-induced degradation of silicon heterojunction photovoltaic modules

Abstract

We investigate the effect of temperature and pre-annealing on the potential-induced degradation (PID) of silicon heterojunction (SHJ) photovoltaic (PV) modules. SHJ PV modules show a faster decrease in short-circuit current density (J sc) at higher temperatures during PID tests. We also observe a complex relationship between the degree of the J sc decrease and temperature during the PID tests. Pre-annealing before the PID tests at sufficiently high temperatures leads to the complete suppression of the PID of SHJ PV modules. The decrease in J sc is known to be due to the chemical reduction of indium (In) in transparent conductive oxide (TCO) films in SHJ cells, in which water (H2O) in SHJ modules is involved. These indicate that H2O may out-diffuse from the SHJ PV modules during a PID test or pre-annealing at sufficiently high temperatures, by which the chemical reduction of indium in TCO to metallic In is suppressed.