Optical Characterization of “Rondine ® ” PV Solar Concentrators

The collection properties of nonimaging “Rondine® ” PV solar concentrators are investigated by indoor measurements of the angle-resolved optical efficiency. We illustrate two different methods to draw the optical efficiency curve. The first one, briefly called as “direct method”, is performed by producing a uniform and collimated beam of known flux impinging on the input aperture of the concentrator at different incidence angles, and by measuring the flux collected at the exit aperture. The second method, called “inverse method”, is based on a reverse illumination procedure, whereby a lambertian diffused light is produced at the exit aperture of the concentrator, and the radiance of the beam transmitted backwards from the input aperture is measured at different directions in space. The obtained results are similar for the two methods, but the “inverse method” is largely to be preferred for the simplicity of the experimental apparatus and the extreme quickness of execution.