Extruding plastic plate (10) with a finely textured surface (8) uses a co-extrusion plant (1,2) and a three-roll polishing stack (4,5,4'), one roll (5) of which has a textured surface (7). The coextruded plate consists of a high viscosity polymer forming a base onto which a lower viscosity polymer is extruded. A Fresnel lens mfd. by the process is claimed as is the use of the plastic plate (10) with a linear Fresnel lens surface structure (8) as a light collector in a solar heat panel. Also claimed is a solar heat panel including a tube for the heat transfer fluid and the claimed lens which directs the light onto the tube.
