Comparative techno-economic analysis of different PV-assisted direct solar hydrogen generation systems

Abstract

Photovoltaic (PV) assisted direct solar hydrogen generation (DSHG) is an alternative pathway for large-scale renewable hydrogen generation, where solar energy is directly used to drive water splitting in a compact integrated system. Despite promising improvements in efficiency, the robust technoeconomic analysis required to quantitatively understand the opportunities and challenges of using DSHG to reduce the cost of renewable hydrogen production has been lacking. Herein, we compare three different DSHG module configurations with varying levels of integration between PV and electrocatalysts, covering the variety of different systems that have been proposed in the literature. Photoelectrochemical (PEC) configurations have the highest level of integration, with catalyst directly coated on the PV components to form photoelectrodes. In contrast, PV–electrochemical configurations (PV–EC) consist of series connected photovoltaic and electrochemical (EC) components connected via wires. It is also possible to decouple PV–EC systems, such that the PV and EC components are connected through a dc–dc convertor to optimize power management. Our analysis demonstrates that the cost of hydrogen produced by these systems depends on the configuration, and that the decoupled PV–EC systems produce the lowest cost hydrogen. Regression analysis identifies membrane cost and lifetime, gas handling and compression, and O&M as the key cost components impacting the LCOH. Comparison of DSHG and PV–Electrolysers (PV–E) highlights the conditions under which DSHG could out-compete PV–E, emphasizing it is a competitive technology within the uncertainty of the analysis. Using these results, we identify where research efforts should focus to drive down the cost for large scale deployment of DSHG systems to achieve LCOH of <2 $ per kgH₂.