Reduction in the short-circuit current density of silicon heterojunction photovoltaic modules subjected to potential-induced degradation tests

- SHJ PV modules undergo PID characterized by a reduction in short-circuit current.
- The reduction is due to optical loss that probably occurs in the front TCO layer.
- SHJ PV modules have high PID resistance.
- The high reliability can be further improved by using ionomer encapsulants.

This letter deals with the potential-induced degradation (PID) of silicon heterojunction (SHJ) photovoltaic (PV) modules. After rapid indoor PID tests applying a voltage of −1000 V at 85 °C, the modules exhibited a significant reduction in short-circuit current density (Jsc). On the other hand, the dark current density-voltage characteristics of the modules were intact after the PID tests, indicating that the reduction in Jsc is attributed not to carrier recombination but to optical loss. A degraded module slightly recovered its performance loss upon applying a positive bias but complete recovery was not observed, showing that the PID of SHJ PV modules is not reversible. A module with an ionomer encapsulant showed high PID resistance, revealing that the degradation of SHJ PV modules can be prevented by the use of ionomer encapsulants.