NOVELTY - The process comprises producing a high-transparency polymer layer from a pellet formulation by melting in a first extruder, withdrawing the layer via a slot die, structuring a surface of the polymer layer by a gravure-bearing cooled roll or drum, which has a temperature gradient of 60 degrees C on a roll surface, applying a second polymer layer on an upper side of the first polymer layer using a second extruder or by coextrusion, and applying a third polymer layer on the lower side of the first polymer layer using a third extruder or by coextrusion.    USE - The process is useful for producing a concentrator, which is useful for solar power generation, for point-concentrated focusing of solar radiation onto a two-dimensional geometry of a photovoltaic cell and a stirling motor of a thermal receiver of a solar thermal collector and for linear-concentrated focusing of solar radiation onto a linear arrangement of photovoltaic cells or onto an absorber tube of a solar thermal collector (all claimed), where the concentrator is optical concentrator.    ADVANTAGE - The process is capable of efficiently producing the concentrator with improved lifespan, durability and performance, high strength and good dimensional stability thus enabling economic production and efficient concentration of solar radiation onto objects such as solar cells or absorber units.    DETAILED DESCRIPTION - The process comprises producing a high-transparency polymer layer from a pellet formulation by melting in a first extruder, withdrawing the layer via a slot die, structuring a surface of the polymer layer by a gravure-bearing cooled roll or drum, which has a temperature gradient of 60 degrees C on a roll surface, applying a second polymer layer on an upper side of the first polymer layer using a second exturder or by coextrusion, and applying a third polymer layer on the lower side of the first polymer layer using a third extruder or by coextrusion. The polymer layer, after the structuring step, has an optical surface structure on a lower side of a concentrator. The optical surface structure forms Fresnel lenses, and the concentrator is equipped with UV absorber and UV stabilizer. The second and/or the third polymer layer is a multilayer coextrudate. The second and third polymer layers or component layers of the second and third polymer layers are equipped with the UV stabilizers and UV absorbers. The UV absorber is a triazine type absorber and benzotriazole type absorber, and the UV stabilizer is hindered amine light stabilizer compound. A surface of the concentrator is coated with a scratch-resistant, antisoil coating and/or antireflection coating before the structuring process. A refractive index of the first polymer layer forms a square root of a refractive index of the second polymer layer. An INDEPENDENT CLAIM is included for a concentrator.