Selection of Solar Concentrator Design Concepts for Planar Photoelectrochemical Water Splitting Devices

Abstract

Photoelectrochemical water splitting is a promising pathway for solar-driven hydrogen production with a low environmental footprint. The utilization of solar concentrators to supply such water splitting devices with concentrated solar irradiation offers great potential to enhance the economic viability of water splitting at “sunny” site locations. In this work, we defined a set of functional requirements for solar concentrators to assess their suitability to power such water splitting devices, taking into account concentrator optical performance, device coupling efficiency, perceived system complexity, as well as technological costs and risks. We identified, classified and compared a broad range of existing solar concentrator design concepts. Our geometrical analysis, performed on a yearly basis with a one-minute time step, shows that two-axis tracking concentrators with water splitting devices positioned parallel to the optical aperture plane exhibit the highest potential, given the initial conditions applied for the device tilt constraints. Demanding an angle of at least 20° between horizontal and the front side of the water splitting device, allows the device to be operational for 97% of the daylight time in Seville, Spain. The relative loss with respect to the available direct normal irradiance is estimated to 6%. Results moderately depend on the location of application, but generally confirm that the consideration of tilt angle constraints is essential for a comprehensive performance assessment of photoelectrochemical water splitting driven by concentrated sunlight.