1. A solar energy collection system comprising: at least one receiver configured to receive on an external surface thereof reflected solar radiation from heliostats, the at least one receiver housing at least one fluid conveying member for conveying a working fluid therethrough, the external surface having a light-absorbing coating thereon; and light-reflecting elements disposed on the external surface, the light-reflecting elements producing at least partially diffuse reflection of light energy reflected thereon by the heliostats; an imaging device for determining the apparent brightness of each of the light-reflecting elements and providing a brightness signal; and a controller configured to compute a flux distribution across the surface of the at least one receiver responsively to the apparent brightness signal.