Impact of intermittent operation on photovoltaic-PEM electrolyzer systems: A degradation study based on accelerated stress testing

Integrated systems of PEM water electrolyzers (PEMWE) and photovoltaic (PV) power plants are a promising method for the production of green hydrogen with zero-carbon emissions. Despite their potential, matching the intermittent nature of solar energy with the continuous demand for hydrogen production remains a challenge. In directly coupled PV-H2 systems, the electrolyzer is operated dynamically with frequent load changes and shutdown (SD) periods whereas battery assisted systems enable steady operation at a fixed power rate. In this study, two accelerated stress tests (ASTs) were designed based on the data from a 100 kWp PV plant to mimic failure under real-life conditions in a single cell PEMWE. The first AST represents a time-accelerated PV-profile that depicts power imbalances during daytime and idle periods at night, where the cell is kept at open circuit voltage (OCV). In the second AST, the SD periods are compensated by a protective current of 0.3 A cm-2 to simulate a battery assisted system. A thorough electrochemical and physical characterization revealed a correlation between SD periods and the accelerated degradation of PEMWE components. With regard to the battery-supported AST, a lower degradation rate of -3 mV h-1 at 1 A cm-2 compared to -11 mV h-1 for the intermittent operation was recorded.