Potential-Induced Degradation of the Shunting Type: on the Origin of Sodium in Shunt Paths

Abstract

Potential-induced degradation rapidly and significantly affects the photovoltaic (PV) module's performance due to a high potential difference across the PV cell and the grounded module's frame.[1] PID has various types where PID of the shunting type (PID-s) is common within silicon PV cells.[2] Extensive research already points towards sodium (Na) ions as the root cause of the efficiency degradation under PID-s.[3] However, the origin of the Na ions is still under debate. Some publications state that the soda-lime glass (SLG) cover of the PV module is the main source of the Na ions. In contrast, others have proven to degrade solar cells in the absence of an encapsulation material and front cover glass. [3-6] With this work, we try to find an answer to the current debate and thus find the source of the Na ions causing PID-s.