NOVELTY - 100 parts mass Polyester resins having resin temperatures of more than (TgPol-20) and less than (TgPol+65), and moisture content of 200 ppm or less, and 0.1-4 parts mass terminal blocking materials are supplied in a cylinder (10) from supply port (12) of a twin-screw extruder (100), inlet-side pressure of a gear pump is adjusted to 1-3 MPa, and polyester resin is melt-extruded from extrusion opening. The melt-extruded polyester resin is formed into a film in a sheet form, to obtain polyester film.    USE - Manufacture of polyester film used for protection sheet for solar cell module (all claimed) and photovoltaic cell.    ADVANTAGE - The method enables manufacture of polyester film having excellent hydrolysis resistance and durability. The solar cell module using the polyester film has excellent electric power generation efficiency for long period of time, and transmittance.    DETAILED DESCRIPTION - Manufacture of polyester film involves using a twin-screw extruder having two screws (20A, 20B) arranged rotatably in the cylinder having a raw material supply port which supplies raw resin, and an extrusion opening which extrudes molten resin, and a cylinder, and a polyester manufacturing apparatus having a polyester film forming machine with a gear pump which discharges molten resin. A molten resin extruded from the twin-screw extruder is sucked, temperature of cylinder wall in supply direction of the raw resin supplied to cylinder from raw material supply port is adjusted to temperature of less than (TgPol-10) (where TgPol is glass transition temperature (in degrees C) of raw resin containing polyester). 100 parts mass Polyester resins having resin temperatures of more than (TgPol-20) and less than (TgPol+65), and moisture content of 200 ppm or less, and 0.1-4 parts mass terminal blocking materials are supplied in a cylinder from the supply port of twin-screw extruder, inlet-side pressure of a gear pump is adjusted to 1-3 MPa, and polyester resin is melt-extruded from extrusion opening. The melt-extruded polyester resin is formed into a film in a sheet form, to obtain polyester film. INDEPENDENT CLAIMS are included for the following:    (1) protection sheet; and    (2) solar cell module.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of twin-screw extruder. (Drawing includes non-English language text)    Cylinder (10)    Supply port (12)    Extruder exit (14)    Screws (20A,20B)    Twin-screw extruder (100)