Double-tailored dual-mirror nonimaging concentrators for maximum-performance solar concentration

A nonimaging strategy wherein two mirror contours are tailored for concentration near the tendue limit is explored, prompted by solar applications where a sizable gap between the optic and absorber is required. Subtle limitations of this simultaneous multiple surface method approach are derived, rooted in the manner in which phase space boundaries can be mapped according to the edge-ray principle. The fundamental categories of these optics are identified, only a minority of which can pragmatically offer maximum concentration at high collection efficiency. Illustrative examples confirm that acceptance half-angles as large as 30 mrad can be realized at a flux concentration of similar to 1000.