Preliminary investigations on the evacuated PVT-driven methanol electrolysis for enhanced solar hydrogen production

Methanol is a promising liquid fuel and hydrogen carrier. Its electrolysis requires both electrical and thermal energy for efficient operation. Although the theoretical electrolysis voltage is extremely low, the process still requires coordinated electrical and thermal inputs to satisfy the overall energy demand. To address this challenge, this study proposes an integrated system coupling methanol electrolysis with an evacuated photovoltaic-thermal (PVT) collector, which can simultaneously and sustainably provide electricity and medium-/low-temperature heat from the same solar aperture. Owing to vacuum insulation, the evacuated PVT collector can significantly suppress thermal losses, thereby increasing the attainable thermal output temperature and providing a thermal supply well matched to the energy requirements of methanol electrolysis. A thermodynamic analysis was first conducted to clarify the partitioning of the overall energy demand between electricity and heat in methanol electrolysis. A coupled opto-electro-thermal model, validated by experimental data, was then developed to evaluate the integrated PVT-electrolysis system. The results show that the useful thermal output recovered from the evacuated PVT collector can meet part of the heat demand of methanol electrolysis, thereby reducing the electrical input to the electrolyzer. Consequently, the PVT-driven methanol electrolysis system decreases electricity consumption by more than 40% and achieves a daily hydrogen output 3.62 times higher than that of the PVT-driven water electrolysis system. These results highlight the potential of synergistically integrating methanol electrolysis with evacuated PVT technology to advance efficient and practical solar-driven hydrogen production.