The solar flux received by the collector is first reflected on the mirrors of the concentrators, then it generally passes through a glazing material for thermally insulating the receiver where it is absorbed by a suitable surface. Reflection, transmission through the glazing, and absorption result in optical losses, generally characterized by an effectiveness t. In high concentration collectors, only the direct component of solar radiation can be directed to the receiver, as the diffuse component cannot be concentrated.

The absorber heats up and loses heat to the outside mainly in the form of radiation and convection. This loss can be characterized by a coefficient of thermal losses U. A thermal fluid cools the absorber, taking useful heat that is then converted or transferred for different uses.