Large aperture solar concentration using Fresnel lens arrays and multibeam confocal optical paths on a Stirling engine

High-concentration solar power systems, such as dish Stirling engine systems, typically necessitate the complex assembly of multiple parabolic mirror segments for the concentrator. An intriguing alternative involves utilizing an array of lightweight, easily manufactured Fresnel lenses to achieve a large effective aperture. In this study, we developed a confocal system that utilizes a large Fresnel lens array, successfully driving a Stirling engine. Experiments demonstrated that while redirecting the high-concentration solar flux flow using mirrors was not feasible, it was possible to alter the direction of the low-concentration solar flux flow. This adjustment facilitated the successful confocal arrangement of a four-beam system, effectively quadrupling the aperture of the concentrator. This approach presents a novel method for realizing large-aperture concentrators through the confocal configuration of a Fresnel lens array.