NOVELTY - Use of (a) at least one polyalkyl(meth)acrylate and (b) at least one substituted N,N'-diphenyl-oxalamide derivative (I), for manufacturing solar cell modules, is claimed. The solar cell module comprises at least one element comprising polyalkyl(meth)acrylate. The concentration of (I) in the element comprising polyalkyl(meth)acrylate is as given in the formula of the specification.    USE - The polyalkyl(meth)acrylate and the compound (I) are useful for manufacturing solar cell modules (claimed), preferably for manufacturing light concentrators for solar cell modules.    ADVANTAGE - The solar cell modules: reduces the loss of efficiency of the solar cells with long term outdoor use, preferably at high temperatures and/or at high humidity; and exhibits excellent weather resistance, high heat resistance, high light transmission and very low water absorption.    DETAILED DESCRIPTION - Use of (a) at least one polyalkyl(meth)acrylate and (b) at least one substituted N,N'-diphenyl-oxalamide derivative of formula (I), for manufacturing solar cell modules, is claimed. The solar cell module comprises at least one element comprising polyalkyl(meth)acrylate. The concentration of (I) in the element comprising polyalkyl(meth)acrylate is as given in the formula of the specification.    R1, R2 = 1-20C (cyclo)alkyl.    An INDEPENDENT CLAIM is also included for a solar cell module comprising either molded part containing (a) and (b), or (a1) at least one photovoltaic element (101), (b1) at least one converging lens, which comprises at least one polyalkyl(meth)acrylate, and (c1) at least one transparent pane containing at least one compound (I).    DESCRIPTION OF DRAWING(S) - The drawing 1 shows a schematic representation of the solar cell module. The drawings 2A and 2B show a schematic representation of the cross sectional view and the plan view of the photovoltaic element, respectively.    Photovoltaic element (101)    Conductive substrate (201)    Reflective layer (202)    Photoactive semiconductor layer (203)    Transparent conductive layer (204)