NOVELTY - Producing a concentrator for solar energy production, comprises producing a highly transparent plastic layer from a granulate formulation by melting in an extruder, removing over a slot die and structuring the film surface over a support engraving, cooled roller or drum exhibiting a temperature gradient of at least 60 degrees C on the roller surface, on the lower side of the concentrator. The plastic layer, after the structuring, exhibits an optical surface structure on the lower side of concentrator, which forms at least one Fresnel lens.    USE - The concentrator exhibiting angular or radial Fresnel lens is useful for point concentrated bundling of solar radiation on the 2-dimensional geometry of a photovoltaic cell and a stirling engine of a thermal receiver from a solar thermal plant. The concentrator exhibiting linear Fresnel lens is useful for linear concentrated bundling of solar radiation on a linear arrangement of photovoltaic cells, or onto an absorber pipe of a solar thermal collector (all claimed).    ADVANTAGE - The method is carried out in a cost efficient manner for producing the concentrator which provides: efficient concentration of solar radiation on objects, e.g. solar cells or absorber units, regardless of its geometry; and exhibits a high durability and high optical performance when used in extreme and challenging climates.    DETAILED DESCRIPTION - Producing a concentrator, comprises producing a highly transparent plastic layer from a granular formulation by melting in an extruder, removing over a slot die and structuring the film surface over a support engraving, cooled roller or drum exhibiting a temperature gradient of at least 60 degrees C on the roller surface, on the later lower side of the concentrator. The plastic layer, after the structuring, exhibits an optical surface structure on the lower side of concentrator, which forms at least one Fresnel lens. The concentrator is provided with at least one UV absorber and at least one UV stabilizer. An INDEPENDENT CLAIM is also included for the concentrator viewed from the light source comprising the UV stabilizer and the UV absorber containing second plastic layer with a thickness of 5-500 mu m, preferably 10-250 mu m, and a first plastic layer with a thickness of 0.1-25 mm, preferably 0.5-15 mm, and the lower side of the concentrator is surface structured in the form of at least one Fresnel lens.