Design and testing of a uniformly illuminating nontracking concentrator

Abstract The transverse parabolic shape of the reflecting surface in the Winston nontracking solar concentrator has been modified so that the illumination at the receiver is exactly uniform for certain angles of incidence and reasonably uniform for other angles. An exact mathematical expression has been derived for the transverse shape of the reflecting surface which reduces to the Winston parabolic shape in the limit of extreme nonuniformity. The performance of the proposed design has been analysed theoretically as well as tested experimentally. Experimental studies show that the illumination at the receiver remains uniform to within 10–12 per cent with no lateral shadows throughout a typical solar day. The proposed design should therefore, be quite suitable for photovoltaic applications.