TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The photocatalyst contains an inorganic material with an absorption edge of greater than or equal to 550 to less than or equal to 650 and transparent of greater than or equal to 1000 nm to less than or equal to 1200 nm. The photocatalyst comprises a material including rare earth compound of formulae ((L)2M1O6:RE) (I), ((L)2(M1)2O9:RE) (II), ((L)2(M1)3O12:RE) (III), ((L)2(M1)4O15:RE) (IV), (A1L(M)2O8:RE) (V), (LM2O4:RE) (VI) and/or ((L)6MO12) (VII). The photocatalyst is arranged in the path of the incident light before the solar cell. The solar cell is silicon solar cells, preferably based on alpha -silicon, protocrystalline silicon or crystalline silicon, copper containing solar cell of formula (CuL(S, Se)2) (VIII) (CIS solar cells), (aluminum, gallium)-arsenic solar cells, Graetzel cells (electrochemical solar cells, especially those based on titania nanoparticles and Ru2+ complexes and a redox mediator, e.g. potassium triiodide/ potassium and iodide) or ball element solar cells. The converter includes ethylene-vinyl acetate polymers, i.e. copolymer of ethylene-vinyl acetate as matrix material, and polyoxymethylene, polymethyl methacrylate, polystyrene or polycarbonates polymers are provided with suitable inorganic materials including europium doped strontium fluoride, europium doped yttrium(III) fluoride, yttrium, europium doped yttrium(III) fluoride, yttrium, europium doped sodium yttrium fluoride, yttrium, thulium doped sodium yttrium fluoride, yttrium, europium doped barium yttrium fluoride, yttrium, europium doped yttrium oxy-chloride, yttrium, europium doped yttrium oxysulfide and/or yttrium, thulium doped yttrium oxysulfide, or yttrium, europium or yttrium, thulium co-activated up-converter.L = La, Y, Gd or Lu;M1 = Mo or W;M2 = V, Nb or Ta;A1 = Li, Na, K, Rb or Cs; andRE = rare earth, preferably Ce or Pr.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The system further comprises a converter (30) which is capable of to convert at least partially UV radiation in low-energy radiation. The converter is arranged in the path of the incident light behind the solar cell.