CPV and illumination systems based on XR-Kohler devices

The XR-Kohler concentrator(1) is a design that has the possibility to work under high concentration, maintaining the high acceptance angle and high irradiance uniformity on the solar cell. It is an on-axis free-form design that consists of a reflective (X) and refractive (R) surface. For a geometrical concentration of about 800x the simulated results show an acceptance angle of +/- 1.79deg with high irradiance uniformity on the solar cell. This article shows the design results of the XR-Kohler and also a novel passive cooling system (LPI patented) that keeps the solar cell operation temperature under 100 degrees C at extreme conditions (wind speed = 0 m/s, module tilt angle = 45deg and T-a = 50 degrees C). The results of using the XR-Kohler device as a collimator when the light source has very high non-uniform luminance distribution, i.e. multichip LEDs, are also here presented.