Diffuse optical properties of a Fresnel lens sunlight concentrator.

A combined module that combines a concentrator with planar photovoltaic circuits provides energy conversion of both parts of global terrestrial radiation: direct sunlight by concentrator solar cells and scattered (diffuse) sunlight by planar (non-concentrator) photoconverters. The decrease in Fresnel lens concentrating ability is usually associated with imperfections in the optical refractive surfaces, where some part of the direct light, which arrives normal to the surface of the Fresnel lens and is intended to be concentrated, becomes scattered and directed off the highly efficient concentrator solar cell. The diffuse light flux propagates inside the volume of the combined photovoltaic module.

Temperature dependencies of the refractive index for Al-Ga-In-As metamorphic layers.

Temperature dependencies of the refractive indices, , for and metamorphic layers with =0.06-0.25 have been determined.