A solar collector/receiver for a full-spectrum solar energy system is being designed by a research team lead by Oak Ridge National Laboratory and the University of Nevada, Reno. This solar energy system is unique in that it utilizes the majority of the solar spectrum. The collector/receiver is a modified Cassegrain system that uses a large parabolic mirror and a secondary mirror comprised of multiple planar segments. The secondary mirror segments are coated with a spectrally selective cold mirror coating that lets the infrared (IR) energy pass through while reflecting the visible light.
The focus of this paper is on determining whether a refractive or a reflective non-imaging (NI) tube will produce the most uniform irradiance of the IR energy on the thermophotovoltaic (TPV) array. It has been shown that a rectangular NI tube will work well for the prototype system3. The results herein show that a reflective NI tube will perform best for this system, with a short length, minimum/maximum flux ratio of 0.94 and power output of 37W. It is also shown that a square shaped TPV array can increase the optical efficiency by 9% and the overall system efficiency by 2%.