Investigation of a novel concept for hydrogen production by PEM water electrolysis integrated with multi-junction solar cells

•A 2D model of a PEM water electrolyzer is developed and validated.•A novel system integrating PEM and multi-junction solar cells is proposed.•The model is applied to the simulation of the novel system.•The integration of PEM and MJ cells enhances the hydrogen production efficiency. A 2D finite element model of a high-pressure PEM water electrolyzer is developed and validated over experimental data obtained from a demonstration prototype. The model includes the electrochemical, fluidic and thermal description of the repeating unit of a PEM electrolyzer stack. The model is applied to the simulation of a novel system composed by a high-temperature, high-pressure PEM electrochemical cell coupled with a photovoltaic multi-junction solar cell installed in a solar concentrator. The thermo-electrochemical characterization of the solar-driven PEM electrolysis system is presented and the advantages of the high-temperature operation and of the direct coupling of electrolyzer and solar cell are assessed. The results show that the integration of the multi-junction cell enhances the performance of the electrolyzer and allows to achieve higher system efficiency compared to separated photovoltaic generation and hydrogen production by electrolysis.