Shading-aware and degradation-conscious two-layer optimization for isolated indirect multi-stack photovoltaic-driven hydrogen systems

The rising demand for sustainable hydrogen production has positioned photovoltaic (PV)-driven water electrolysis as a promising pathway for green hydrogen, particularly in solar-rich regions. However, partial shading (PS) caused by environmental obstructions, dust, or surrounding structures severely reduces PV performance, leading to power fluctuations, uneven distribution, and accelerated degradation in multi-electrolyzer (ELZ) stacks. In indirect PV-driven hydrogen systems, existing maximum power point trackers (MPPTs) cannot fully address these challenges, and no prior work has simultaneously tackled both shading-induced inefficiencies and stack degradation. To bridge these gaps, this paper proposes a two-layer optimization framework that integrates both planning and operation stages. In the planning stage, a shading-aware PV array configuration determines the optimal fixed configuration (OFC) and the required number of ELZ stacks based on representative seasonal irradiance, ensuring long-term compatibility between PV output and stacks demand. In the operation stage, a degradation-conscious power coordination strategy dynamically allocates power among stacks to minimize discrepancies in accumulated voltage degradation. The proposed framework is benchmarked against state-of-the-art approaches under diverse seasonal conditions. Simulation results show that it achieves up to 30.8% higher PV energy yield, reduces maximum accumulated voltage degradation by 3.3993% compared with rotational coordination, and maintains degradation discrepancies within 0.0038 V across stacks in winter . These improvements highlight the importance of combining shading-awareness with degradation-conscious operation to enhance the efficiency and durability of PV-driven hydrogen production under real-world constraints.