Cylindrical Fresnel lens: An innovative path toward a tracking-less concentrating photovoltaics system

Abstract

We here invent an implicitly new optical device - cylindrical Fresnel lenses historically used in the decades-old lighthouse concentrator to find application in the field of concentrator photovoltaic, with numerous demonstrations of exotic features in optics. The precious attribute of such a solar concentrator is its ability to grant a focal point sequence, essentially distributed over an arc at any light incidence. The other striking merit of this design is its high acceptance angle, about 60°, at hand and even up to 90°, ideally. We have applied this approach to a simplified principle-of-concept model that closely depicts the octagonal cylindrical Fresnel lens in essence. This convergence feature was evidenced in a mock-up model through optical simulation and further consolidated by electrical characteristics analysis. Specifically, the simulation affirmed that an optimal structure can attain a concentration ratio of ∼23 and an optical efficiency of ∼70%. We indeed confirmed through an outdoor experiment a 16-fold improvement of current gain, which was close to the simulation result. Of further exceptional interest in such a design is its compatibility with two mature common tracking mechanisms: daily or yearly single-axis tracking, leaving room for design compromises. This design leaves ample margins for simple and low-cost light couplers, which are advantageous in affordable concentrator photovoltaic systems. In addition, the quantitative assessment unravelled that the generated power can be enhanced 1.3× in comparison with the flat Silic panel. We describe the potential realization of the large-scale of the model, making this solar concentrator amenable to commercialization.