Maximum conversion efficiency for the utilization of multiply scattered solar radiation

The effective temperature of diffuse solar radiation decreases by increasing the number of scatterings. In the case of flat-plate collectors the maximal efficiency of singly or multiply scattered diffuse solar radiation is 0.053. The maximal efficiency can be improved by concentration. Singly scattered radiation has a maximum efficiency of 0.573. The Petela-Landsberg and Jeter formulae give good upper bounds for the maximal efficiency of solar collectors.