Stationary low concentrator collectors (C < 2), of the CPC type, are of great interest for thermal energy supply of industrial processes, at temperatures below or equal to 100 degrees C. In particular, concentrators with fully illuminated V inverted absorbers have attractive properties for thermal energy conversion. Numerical analysis of the geometric and optical characteristics of different low concentration CPC's (C between 1 and 2) with fully inverted wedge absorbers, shows that the cavities with the minimal relationship between the length and height of the reflector surface and the aperture, (L/A) and (H/A), and the lower average number of reflections < n > correspond to the lowest angular acceptance concentrator. If a concentration of 1.2 is desired, the smallest ratios of (L/A) and (H/A) and mean number of reflections (n) occur for C=2 (theta(a) = 30 degrees). However, when the annual generated thermal energy is also considered (for example, for Recife, tilt equals latitude, fluid temperature equals 50 degrees C, East West orientation), a very large maximum value in the concentration region between 1.4 and 1.6 (acceptance angles of 38.68 degrees e 45.58 degrees) occurs. The simulation results indicate, that while the operational temperature rises, the ratio between the annual generated thermal energy by the CPC and a good quality flat-plate collector becomes greater than 1: for CPC with 1.2 concentration these ratios become 1.0 at 50 degrees C and 1.35 at 80 degrees C. The improvement in the reflectivity of the reflector surface of the CPC rises significantly this relation, i.e., if the reflectivity exceeds from 0.86 to 0.96 the CPC of the concentration relation 1.2, operating at 80 C may generate 55% more thermal energy than flat-plate collector. (C) 2011 Elsevier Ltd. All rights reserved.