Abstract: A thermophotovoltaic converter of the type comprising a concentrating optical system and a transducer for solar radiation provided with at least one lens and with at least one photovoltaic cell is described.The principal feature of this converter is that the aforementioned transducer comprises at least a radiator having an irradiating surface substantially facing the sensitive surface of the photovoltaic cell and a selective filter disposed between the photovoltaic cell and the aforementioned radiator.

Abstract: A solar energy absorber comprises a thermally-insulated duct housing a plurality of longitudinally-extending absorbing plates and having a slit located at the focal axis of an elongate, optical focusing system. The plates are parallel to the plane of symmetry of the optical system and are spaced apart such that focused energy incident through the slit falls upon an entire surface of each plate, any reflected energy being returned to the plates by a plane mirror located on the opposite side of the plates from the slit and by internal reflecting surfaces of the duct such that substantially all the energy is absorbed: this energy is given up to an air flow through the duct, in use.