A two-dimensional cone concentrator for sunlight was theoretically and experimentally studied. The calculation revealed the maximum number of reflections that sunlight could make before exiting the cone. A higher number of reflections caused the sunlight to bounce backward to the entrance of the cone. The characteristics and geometric parameters of the cone were assessed. As the cone angle increased from 45 degrees to 90 degrees, the calculated concentration ratio, taking the reflection coefficient into account, increased nonlinearly from one to infinity, while the height of the cone also increased from zero to infinity. The experimental concentration ratio was found to be less than the theoretical one in all cases. (c) 2007 Elsevier Ltd. All rights reserved.