Diagnosis of faults in photovoltaic modules via full-bias EIS scanning and dynamic parameter analysis

Abstract

The rapid expansion of photovoltaic (PV) installations has presented significant challenges for operations and maintenance (O&M), particularly in early defect detection and precise fault identification to ensure system reliability. While traditional DC inspection methods detect overall performance changes, they are insufficient for identifying internal or localized defects within modules. This study extends electrochemical impedance spectroscopy (EIS), traditionally applied to individual solar cells, to full-scale PV module analysis. Under controlled conditions, several common defects were simulated, including interconnect ribbon disconnections, cell cracking, potential-induced degradation (PID), and bypass diode short circuits. Impedance parameters were systematically analyzed across a voltage range of 0–31 V. The results reveal that interconnect ribbon disconnections increase series resistance and reduce parallel resistance by altering the ohmic resistance at metal contacts. Cell cracking, irrespective of crack type, significantly reduces the time constant, reflecting higher minority carrier recombination rates. This reduction is particularly important for differentiating between interconnect ribbon disconnections and crack-induced defects. Conversely, PID and bypass diode failures exhibit distinct impedance signatures, enabling clear differentiation from other fault types. These findings highlight the potential of EIS as a powerful diagnostic tool for identifying and distinguishing various fault modes in PV modules.