A Capacity Ratio Configuration Method for the PV- PEMWE System Considering Rapid PV Power Fluctuations and Electrolyzer Durability

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Abstract
The inherent intermittency and volatility of photovoltaic (PV) power cause rapid fluctuations on the DC bus. In off-grid PV hydrogen production systems, proton exchange membrane electrolysis (PEMWE) is used to smooth these power fluctuations. However, a temporal mismatch exists between rapid PV variations and PEMWE capacity. This allows power disturbances to affect internal components of PEMWE, accelerating degradation. This paper establishes a link between the electrical dynamics and durability of PEMWE. A dynamic overpotential response model is developed to characterize PEMWE behavior under PV power fluctuations. A PV/PEMWE capacity ratio configuration method is then proposed, incorporating PV power fluctuation and PEMWE durability constraints to define the feasible sizing region. The simulation results demonstrate that the proposed method suppresses PV power fluctuations and extends electrolyzer lifespan for more simple durability constraint calculations. Consequently, the levelized cost of hydrogen is reduced by 16.9%. This work provides a theoretical basis for efficient sizing in off-grid PV hydrogen production systems.

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