TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The crosslinking activator is chosen from trimethylol propane trimethacrylate and triallyl isocyanurate.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The two outsides layers of the multilayer backsheet for a photovoltaic module consist of a polyamide, preferably the same polyamide. The polyamides for at least one outside layer or both outside layers are composed on the basis of linear and/or branched aliphatic and/or cycloaliphatic and/or aromatic monomers which are chosen from diamines, dicarboxylic acids, lactams and amino carboxylic acids. The polyamide of at least one or both outside layers is chosen from polyamide (PA)12, PA11, PA610, PA612, PA1010, PA1012 and/or PA 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (MACM)12. The material for at least one inside layer is chosen from polyvinylidene chloride (PVDC), cyclic olefin copolymers (COC), polypropylene (PP), ethylene vinyl alcohol copolymer (EVOH), polyphenylene sulfide (PPS), polysulfone (PSU), polyether sulfone (PESU), polyphenyl sulfone (PPSU), polyether ether ketone (PEEK), liquid crystalline polymers (LCP), polyimide (PI) and polyamideimide (PAI) (preferably COC functionalized with maleic anhydride). The multilayer backsheet comprises at least two or three inside layers (4,5,8), with one inside layer consisting of EVOH and the second one preferably of PVDC in the case of at least two inside layers. An outer adhesion promoter layer is arranged between at least one surface of an inside layer and an inner surface of one of the two outside layers. An inside adhesion promoter layer (7, 9) is arranged between one surface each of a first inside layer, second inside layer and/or third inside layer. The material for the adhesion promoter layers is chosen from acrylates, epoxides, polyurethane (PUR), functionalized polyolefins, ionomers and ethylene vinyl acetate (EVA). The material for at least one inside layer is chosen from a group of partly aromatic polyesters which comprises polybutylene terephthalate (PBT), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), with the adjacent outer adhesion promoter layer made of block copolyesteramide having blocks compatible to layers (2, 3, 4, 5) adjacent to the adhesion promoter layer. The blocks of the outer adhesion promoter layer made of block copolyesteramide correspond to the partly aromatic polyester of the inside layer and the polyamide of the outside layer, on which the outer adhesion promoter layer made of block copolyesteramide borders. The multilayer backsheet comprises an inside layer (4) made of a partly aromatic polyester which is connected on both sides by one outer adhesion promoter layer each made of block copolyesteramide with two outside layers made of polyamide. The multilayer backsheet for a photovoltaic module is co-extruded. The polyamides of one or both outside layers contain at least one additive which is chosen from a group which consists of white pigments, UV stabilizers, UV absorbers, antioxidant agents, heat stabilizers, hydrolysis stabilizers, cross-linking activators, flame retardants, layered silicates, fillers, colorants, reinforcing agents, adhesion promoters and impact modifiers. The multilayer backsheet contains a white pigment (preferably titanium dioxide). The polymers or polyamides of the outside layers consist of cross-linked polyamides (preferably cross-linked PA1010 and cross-linked PA12). Preferred Method: The two outsides layers are extruded from one polyamide molding compound each and are co-extruded or laminated onto the at least one inside layer, optionally by using adhesion promoter layers. The multilayer backsheet is formed by two outside layers and at least two inside layers, with one of the inside layers being formed by EVOH and the second preferably by PVDC. At least one of the two outsides layers is laminated onto an inside layer made of PVDC, optionally by using adhesion promoter layers. At least one of the two outsides layers is co-extruded or laminated onto an inside layer made of COC or EVOH, optionally by using adhesion promoter layers. The multilayer backsheet is produced by means of co-extrusion, with one inside layer made of partly aromatic polyester being connected on both sides in each case by way of one outside adhesion promoter layer each made of block copolyesteramide with two outside layers made of polyamide. A crosslinking activator is added a polyamide melt for the outside layers in order to achieve crosslinking of the polyamide. The two outsides layers are extruded as films and crosslinking in the extruded films is triggered by high-energy radiation, preferably by electron radiation. EXAMPLE - No suitable example given.