Achieving flux uniformity with primary optics: a solar concentrator for scaled photoelectrochemical hydrogen production

Scaling photoelectrochemical (PEC) hydrogen production technology requires integration with solar concentrators. However, no concentrator has been developed to address the irradiance requirements of PEC reactors. This work presents an algorithm to design a primary optic that delivers uniformly concentrated irradiance on a planar target, such as a photoelectrode. The algorithm can also be extended to different target geometries. The algorithm is demonstrated through a pseudo-2D parametric ray tracing study of 28 design points, considering real-world errors up to 20 mrad . From the parametric results, a preferred optical geometry is selected and developed into a full-scale concentrator model. The model is subsequently evaluated in a 3D ray tracing study considering realistic optical errors. At combined errors of 8 mrad , the model achieves an optical concentration ratio of 16 at an efficiency of 80 % and coefficient of variation ( C V ) of 16.8 % across the entire target. Considering reasonable shading by a PEC reactor frame, a C V of 10 % can be achieved at an efficiency of 69 % . The proposed concentrator, therefore, produces results competitive with more complex solar concentration solutions employing secondary optical stages. In addition, this work reveals the importance of accurately modelling real-world errors when designing solar optics to achieve flux uniformity.