NOVELTY - The method comprises heat pressing a multi-layer pre-lamination assembly by a heat press unit to obtain a heat pressed multi-layer fluoropolymer film or sheet, where the multi-layer pre-lamination assembly comprises a first oriented fluoropolymer film or sheet layer positioned next to an oriented polyester film or sheet layer. The first fluoropolymer film or sheet layer is positioned to provide one of two opposite outer surface layers of the assembly, consists of fluoropolymer. The oriented polyester film or sheet layer consists of polyester.    USE - The method is useful for obtaining a heat pressed multi-layer fluoropolymer film or sheet that is useful in a backsheet of a solar cell module (claimed), where the backsheet is useful as supports and barriers.    ADVANTAGE - The method is capable of effectively obtaining the heat pressed multi-layer fluoropolymer film or sheet with improved bonding strength thus improving the weatherability, adhesion and mechanical, electrical and barrier properties of the backsheet.    DETAILED DESCRIPTION - The method comprises heat pressing a multi-layer pre-lamination assembly by a heat press unit to obtain a heat pressed multi-layer fluoropolymer film or sheet, where the multi-layer pre-lamination assembly comprises a first oriented fluoropolymer film or sheet layer positioned next to an oriented polyester film or sheet layer. The first fluoropolymer film or sheet layer is positioned to provide one of two opposite outer surface layers of the assembly, consists of fluoropolymer. The oriented polyester film or sheet layer consists of polyester. The multi-layer pre-lamination assembly receives a pressure of 0.01-50 Kgf/cm2 and a heat of 160-200 degrees C. The heat press unit comprises a pair of hot flat plates, and pairs of heated nip rolls. The multi-layer pre-lamination assembly: is heat pressed between the pair of hot flat plates for 0.5-20 seconds; is passed through the pairs of heated nip rolls at a line speed of 0.5-30 m/min; is heated by an infra-red oven; is present in the form of a bi-layer assembly that consists of the first oriented fluoropolymer film or sheet layer and the oriented polyester film or sheet layer, and a tri-layer assembly that consists of the first oriented fluoropolymer film or sheet layer, the oriented polyester film or sheet layer and a second oriented fluoropolymer film or sheet layer consisting of fluoropolymer that is the same or different than the fluoropolymer forming the first oriented fluoropolymer film or sheet layer. The oriented polyester film or sheet layer is positioned between the first and the second oriented fluoropolymer film or sheet layers. INDEPENDENT CLAIMS are included for:    (1) a heat pressed multi-layer fluoropolymer film or sheet; and    (2) a solar cell module.