TECHNOLOGY FOCUS - POLYMERS - Preferred Method: In obtaining heat pressed multi-layer fluoropolymer film or sheet, in step (ii), the heat press means is set at such conditions that the multi-layer fluoropolymer film or sheet receives a pressure of 0.1-50 Kgf/cm2, or preferably 0.5-50 Kgf/cm2, or more preferably 0.5-30 Kgf/cm2 and a heat of 150 degrees C-245 degrees C, or preferably 160 degrees C-220 degrees C, or more preferably 160 degrees C-200 degrees C. The heat press means is a pair of hot flat plates and in step (ii), the multi-layer fluoropolymer film or sheet is heat pressed between the hot flat plates for 0.1 -30 seconds, or preferably 0.5-30 seconds, or more preferably 0.5-20 seconds. The heat press means comprises one or more pairs of heated nip rolls and in step (ii), the multi-layer fluoropolymer film or sheet is passed through the one or more pairs of heated nip rolls at a line speed of 0.01-100 m/minute, or preferably 0.1-50 m/minute, or more preferably 0.5-30 m/minute. Prior to step (ii), the multi-layer fluoropolymer film or sheet is pre-heated to a temperature of 150 degrees C-260 degrees C, or preferably 150 degrees C-245 degrees C, or more preferably 160 degrees C-220 degrees C, or yet more preferably 160 degrees C-200 degrees C. The multi-layer fluoropolymer film or sheet is pre-heated by infra-red heat, air heat, flame heat, electron beam, or laser; or preferably the multi-layer fluoropolymer film or sheet is heated by an infra-red oven. The fluoropolymer is derived from fluoromonomers selected from vinyl fluorides, vinylidene fluorides, tetrafluoroethylenes, hexafluoropropylenes, fluorinated ethylene propylenes, perfluoroalkoxys, chlorotrifluoroethylenes, and its combinations. It is selected from polyvinyl fluorides, polyvinylidene fluorides, and its combinations; or preferably the fluoropolymer is selected from polyvinyl fluorides. Polyester is selected from polyethylene terephthalates, polybutylene terephthalates, polytrimethylene terephthalates, polyethylene naphthalates, and its combinations; or preferably the polyester is selected from polyethylene terephthalates. The multi-layer fluoropolymer film or sheet is in the form of a bi-layer film or sheet that consists essentially of the first oriented fluoropolymer film or sheet layer and the oriented polyester film or sheet layer; or the multi-layer fluoropolymer film or sheet is in the form of a tri-layer film or sheet that consists essentially 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 essentially of fluoropolymer that is the same or different from the fluoropolymer of the first oriented fluoropolymer film, where the oriented polyester film or sheet layer is laminated between the first and the second oriented fluoropolymer film or sheet layers and the first and second oriented fluoropolymer film or sheet layers provide two opposite outer surface layers of the multi-layer fluoropolymer film or sheet. Preferred Film: The heat pressed multi-layer fluoropolymer film or sheet is laminated to a polyolefin film or sheet in such a way that the first fluoropolymer film or sheet layer is positioned next to the polyolefin film or sheet, and the bonding strength between the heat pressed multi-layer fluoropolymer film or sheet and the polyolefin film or sheet, measured according to ASTM D903-38, is at least 17 N/cm, or preferably at least 20 N/cm, or more preferably at least 40 N/cm. It comprises a polyolefinic composition, and where the polyolefinic composition comprises a material selected from ethylene/vinyl acetate copolymers, ionomers, polyethylenes, ethylene/acrylate ester copolymers, acid copolymers, and its combinations; or preferably the polyolefinic composition comprises a material selected from ethylene/vinyl acetate copolymers. Preferred Module: In the solar cell module, the polyolefin comprising the back encapsulant sheet is selected from ethylene/vinyl acetate copolymers, ionomers, polyethylenes, ethylene/acrylate ester copolymers, acid copolymers, and its combinations; or preferably the polyolefin comprised in the back encapsulant sheet is selected from ethylene/vinyl acetate copolymers.