Optical characterisation of 3-D static solar concentrator

The focus of this research is to develop a solar concentrator which is compact, static and, at the same time, able to collect maximum solar energy. A novel geometry of a 3-D static concentrator has been designed and coined the Square Elliptical Hyperboloid (SEH) to be integrated in glazing windows or facades for photovoltaic application. The 4× SEH is optically optimised for different incident angles of the incoming light rays. The optimised SEH is obtained by investigating its different non-dimensional parameters such as major axis over minor axis of the elliptical entry and the height over side of the exit aperture. Evaluating the best combination of the optical efficiency and the acceptance angle, results confirm that the 4× SEH built from dielectric material, working with total internal reflection, is found to have a constant optical efficiency of 40% for an acceptance angle equal to 120° (−60°, +60°). This enables capture of the sun rays all day long from both direct beam light and diffuse light making it highly suitable for use in northern European countries. A higher optical efficiency of 70% is obtained for different dimensions of the SEH; however, the acceptance angle is only 50°. The optimised SEH concentrator has been manufactured and tested; the experimental results show an agreement with the simulation results thus validating the optical model.

► A novel static solar concentrator was designed coined the Square Elliptical Hyperboloid, SEH. ► The geometrical profile of the SEH was optimised for a low concentration ratio of 4 suns. ► The SEH has a large acceptance angle of 120° allowing 8 h of sun collection during the day. ► A prototype of the SEH was made and tested in indoors conditions. ► The experimental results validate the optical model.