NOVELTY - Use of a multilayer film as a back cover of a photovoltaic module, is claimed. The multilayer film comprises (a) a layer facing a solar cell, which is made from a molding material comprising at least 35 wt.% polyamide, based on total molding material, (c) a middle layer made from a molding material comprising at least 35 wt.% thermoplastic polyester, based on total molding material, and (e) a layer arranged outwardly, which is made from a molding material comprising at least 35 wt.% polyamide, based on total molding material.    USE - The multilayer film is useful: as a back cover of a photovoltaic module; and for producing the photovoltaic module (all claimed).    ADVANTAGE - The multilayer film exhibits durable bonding, preferably greater than 20 years, and ensures strong adhesion between the layers.    DETAILED DESCRIPTION - Use of a multilayer film as a back cover of a photovoltaic module, is claimed. The multilayer film comprises (a) a layer facing a solar cell, which is made from a molding material comprising at least 35 wt.% polyamide, based on total molding material, (c) a middle layer made from a molding material comprising at least 35 wt.% thermoplastic polyester, based on total molding material, and (e) a layer arranged outwardly, which is made from a molding material comprising at least 35 wt.% polyamide, based on total molding material, where the adhesion between the layers (a) and (c), and the layers (c) and (e), are produced by (i) adding 0.1-60 wt.% polyamine-polyamide-graft copolymer to layers (a) and/or (e), (ii) adding 0.1-30 wt.% polyamine-polyamide-graft copolymer to layer (c), and (iii) introducing an adhesion promoter layer (b) between (a) and (c), and/or adhesion promoter layer (d) between (c) and (e). The adhesion promoter layer or the two adhesion promoter layers are made from molding material comprising 60-100 wt.% components of 0.1-100 wt.% polyamine-polyamide-graft copolymer, 99.9 wt.% polyamide, and 0-99.9 wt.% thermoplastic polyester, based on total molding material, with the provision that the polyamine-polyamide-graft copolymer is produced using 0.5-25 wt.%, polyamine, based on the graft copolymer, having at least 4 nitrogen atoms, and polyamide-forming monomers comprising lactams, omega -aminocarboxylic acids and/or equimolar combinations of diamine and dicarboxylic acid.