Integrating concentrated solar power with a prototype photoelectrochemical reactor

The direct conversion of solar energy to hydrogen via photoelectrochemical (PEC) water splitting is being researched as a route to decentralised, emissions-free fuel production using only sunlight and water. Despite this, most PEC research remains confined to controlled bench-scale (≈1 cm2) demonstrations, which do not necessarily reflect realistic operating conditions. We present an up-scaled continuous-flow PV-biased photo-electrosynthetic reactor prototype (30 cm2 photoanode + 30 cm2 PV), tested outdoors under dual-sided non-concentrated and concentrated irradiation. Concentrated light was delivered by purpose-built optics comprising linear Fresnel lenses and reflective lightguides, operated with dual-axis solar tracking. The system achieved spontaneous photocurrents up to 77.5 mA and solar-to-hydrogen efficiencies of up to 1.2% under 3-sun illumination. We highlight operational challenges that impact performance, including optical losses, solar flux variability, PV-photoanode performance matching, electrolyte flow-induced shear stress on the nanostructured photoanode and its temperature-related degradation. This work marks a crucial step towards practical PEC hydrogen production and provides a framework for future field testing of up-scaled photo-electrosynthetic devices.