Aging study of a commercial PEM electrolyzer under a realistic photovoltaic profile

- Proton Exchange Membrane (PEM) electrolyzers are well suited for coupling with renewable energy sources for hydrogen production. This work investigates the aging of a commercial 1 kW PEM electrolyzer under photovoltaic (PV)-derived operating conditions. A current profile derived from real PV measurements, reproducing the diurnal solar trajectory, was applied over several hundred hours to characterize degradation under intermittent operation. Stack performance was monitored using polarization curves and Electrochemical Impedance Spectroscopy (EIS). An average degradation rate of 26 μV∙h −1 was measured at 1.5 A∙cm −2 , 70 °C, and ambient pressure. The High-Frequency Resistance (HFR) increased from 2.05 to 2.8 mΩ∙cm 2 at 1.5 A∙cm −2 , indicating increasing ohmic losses, while EIS also revealed substantial non-ohmic contributions to degradation. Prolonged cold shutdown periods were followed by partial transient voltage recovery at start-up. These results characterize the durability behavior of a commercial multi-cell PEM electrolyzer under a realistic PV-derived operating protocol and reveal significant cell-to-cell degradation heterogeneity.