NOVELTY - The multi-layer sheet comprises a first outer layer (2) facing away from a solar cell, a second outer layer (6) facing towards the solar cell, a support layer (4) provided between the outer layers, and an interlayer (3) provided between the support layer and the outer layers. The interlayer comprises 65-85% of a polymer and a filler. The filler comprises 15-35% of fibers. A ratio of a fiber length to an average fiber diameter is 15:1. The fibers (10%) have the length of 50 mu m. The fibers (50%) have the length of 10-15 mu m.    USE - The multi-layer sheet is useful for a back face of a solar module or for a solar cell (all claimed).    ADVANTAGE - The multi-layer sheet has increased tensile strength and high temperature resistance, thus improving light conversion efficiency and life span of the solar cell.    DETAILED DESCRIPTION - The multi-layer sheet comprises a first outer layer (2) facing away from a solar cell, a second outer layer (6) facing towards the solar cell, a support layer (4) provided between the outer layers, and an interlayer (3) provided between the support layer and the outer layers. The interlayer comprises 65-85% of a polymer and a filler. The filler comprises 15-35% of fibers. A ratio of a fiber length to an average fiber diameter is 15:1. The fibers (10%) have the length of 50 mu m. The fibers (50%) have the length of 10-15 mu m. A degree of crystallization of the polymer or polymer alloy of the interlayer is smaller than a crystallization degree of the outer layer. The first outer layer has surface-structures. A surface of the outer layer is 30% greater than a base area of the outer layer, and has a surface roughness of 10-20 mu m. The fibers of the interlayer are coated with a wetting agent. The interlayer further includes an additional polymer. An INDEPENDENT CLAIM is included for a method for producing a multi-layer sheet.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic sectional view of a multi-layer sheet for a solar module.    Multi-layer sheet (1)    First outer layer (2)    Interlayer (3)    Support layer (4)    Second outer layer. (6)