Solar spectrum management for effective hydrogen production by hybrid thermo-photovoltaic water electrolysis

• Solar Hydrogen is key technology to meet major energy demand.
• A hybrid thermo-photovoltaic is promising to effectively produce solar Hydrogen.
• An optimized management of solar spectrum was attempted and accomplished.
• Thermal conversion efficiency is key factor for effective Hydrogen production.

Solar Hydrogen is one of the potential key technologies to fuel human's progress. Optimizing the utilization of sunlight to produce Hydrogen using a hybrid thermo-electrolysis system is useful to promote such technology to broad deployment. Theoretically, it was found that a proper sunlight utilization management by an optimized spectral splitting of the solar spectrum between heating water to produce steam on the one hand and producing electricity via photovoltaic cell to energize the steam electrolysis on the other hand leads to an efficient sunlight to Hydrogen conversion. We report in this theoretical work that 82% sunlight to Hydrogen conversion efficiency can be accomplished from the proposed optimized hybrid thermo-photovoltaic system that employs a 90% efficient solar-thermal convertor. Additionally, it was found that for the proposed optimized hybrid system a quadratic enhancement for both the photovoltaic conversion efficiency and the net solar to hydrogen conversion efficiency can be obtained from employing more efficient solar to thermal convertor. Unlike the previous works, which have handled the optimal photon management in the hybrid thermo-photovoltaic system, our proposed optimization method accounts thoroughly the major losses in the photovoltaic conversion like the thermalization process and the limiting fill factor of the PV cell. Therefore, the methodology and the results of this work are more realistic and could be a useful recipe for an optimal sunlight spectrum management for an effective solar-hydrogen production, which could thrive as a reliable carbon-free-source of energy.