It is shown that in the paraboloid-lens system the limiting solar radiation concentrations at the output and at the medium-air
interface do not exceed their thermodynamic limit in the air. At the same time the lens as a secondary concentrator (SC) has
advantages over the mirror SC because of more complete utilization of the flux from the paraboloid.
Original Russian Text © Sh.I. Klychev, S.A. Bakhramov, Yu.A. Dudko, Sh.D. Paiziev, 2008, published in Geliotekhnika, 2008,
No. 4, pp. 44–46.