Secondary optics design for mitigating tracking errors in a linear CPV system

Maximizing the optical efficiency of a linear CPV system implies to provide an appropriate illumination over the cells, even when an off-axis sun tracking angle occurs. Moreover the small cells size imposes severe requirements on the dimensions of the linear sun image produced by the collector. In contrast, optical aberrations and solar divergence effects contribute to spread the concentrated light. A preliminary study based on ray-tracing simulations has been performed to characterize a model of an existing system. Then a secondary optical device has been especially designed to guarantee a suitable lighting of the cells in a range of tracking angle misalignment -0.5° < < 0.5°. With secondary optics, the optical system has a lower collection efficiency working in focus, but it is more stable in many more realistic operating situations. Keywords: Concentrators, Optical design, Ray tracing