GovindaSamy TamizhMani

Potential‐induced degradation (PID) remains a significant reliability concern for photovoltaic (PV) modules, arising when a voltage difference between the module frame and the solar cells drives unintended leakage current through the glass–encapsulant stack. Although PID ultimately manifests as PID‐s, PID‐p, or PID‐c, the underlying behavior of the leakage current—its magnitude and time dependence—requires clearer electrochemical interpretation. Traditional explanations attribute the initial transient current to bulk capacitive elements of the glass, encapsulant, and antireflection coatings, and the steady‐state current according to their effective ohmic resistance. More recent studies, however, indicate that electrochemical charge‐transfer processes at the encapsulant–metallization interface can play a dominant role in defining the leakage‐current path. This paper develops a unified electrochemical framework for modeling PID leakage current. First, an RC‐equivalent circuit is formulated by combining conventional RC elements with a Randles‐type interface to capture transient leakage current through double‐layer capacitance and faradaic processes at ionic–electronic boundaries. Second, the steady‐state current–voltage behavior is explained using a linearized Butler–Volmer relationship, showing that the measured ohmic response corresponds to the low‐overpotential limit of charge‐transfer kinetics. Analytical results demonstrate that, for typical module materials—3.2‐mm soda‐lime glass and 0.45‐mm encapsulant—the dominant modulators to PID leakage current are the glass surface resistance (under dry‐surface conditions), the glass bulk capacitance, and the encapsulant resistance (under wet‐surface conditions), with soda lime glass surface and EVA/POE encapsulant resistances primarily governing steady‐state current. The proposed electrochemical model is validated against measured leakage‐current data, showing good agreement in both the magnitude and the time‐dependent evolution of PID leakage current.

This study investigates the polarization‐type potential‐induced degradation (PID‐p) of bifacial glass/glass ‐type passivated emitter rear contact ( ‐PERC) modules in the field and their recovery behavior. Modules were installed with three mounting configurations providing different albedo conditions. System voltage ( 600, 1500, and +1500 V) was applied to the cell circuits, with respect to the grounded module frames. No degradation was observed for positively biased modules, but PID‐p was identified on the rear side when cells are negatively biased, with maximum power dropping during the first days and stabilizing at values up to 8% loss. Electroluminescence images revealed a variation of the cells' PID‐p susceptibility within a module. Three parameters were shown to impact the degradation rate: rear albedo light, voltage, and wetness conditions. Degraded modules were recovered either by (1) a positive bias (+1500 V), (2) outdoor illumination with the front side facing sun, (3) outdoor illumination with the rear side facing sun, or (4) dark storage. A recovery pattern was identified with – parameters decreasing to a local minimum before increasing to full recovery. The proposed mechanism is based on the band bending at the rear ‐type Si/AlO interface, going from inversion to depletion and accumulation states. Full recovery was achieved in 2–7 h for the modules recovered with the rear side facing sun, four to eight nights for the modules positively biased at night, and 10–20 days for the modules with the front side facing sun. Dark storage showed slower recovery rates as – parameters were not improving even after 1 month. The recovery rates were correlated with the net Coulombs transferred during the preceding PID stress: When more Coulombs are transferred during the degradation, the extent of degradation is greater, leading to slower recovery rates.