Information theory is applied to the problem of solar radiation collection. We find that the optimum solar concentrator corresponds to a perfect imaging system, i.e., one that images the entire sky on the absorber with no aberrations. For a nonisotropic distribution of radiation at the collector aperture, many thermally separated absorber segments are necessary at the absorber for optimum performance. The heat transfer fluid is first passed through the warm segments and then passed sequentially through the progressively hotter segments.
R. P. Patera and H. S. Robertson, "Information theory and solar energy collection," Appl. Opt. 19, 2403-2407 (1980)