Abstract: A photovoltaic cell comprising a transparent front-plane, an opaque back-plane and an encapsulant resin wherein said back-plane comprises a polyester film comprising a base layer (B) comprising a crystallizable polyester and a heat-sealable layer (A) comprising an amorphous copolyester wherein: (i) said amorphous copolyester is derived from an aliphatic diol and a cycloaliphatic diol and at least one aromatic dicarboxylic acid (ii) said polyester film is disposed in the photovoltaic cell such that layer (A) is in contact with the encapsulant resin.

Abstract: A photovoltaic cell comprising a transparent front-plane, an opaque back-plane and an encapsulant resin wherein said back-plane comprises a polyester film comprising a base layer (B) comprising a crystallisable polyester and a heat-sealable layer (A) comprising an amorphous copolyester wherein: (i) said amorphous copolyester is derived from an aliphatic diol and a cycloaliphatic diol and at least one aromatic dicarboxylic acid (ii) said polyester film is disposed in the photovoltaic cell such that layer (A) is in contact with the encapsulant resin.

Abstract: A biaxially oriented polyester film including polyethylene terephthalate (PET) and at least one hydrolysis stabilizer selected from a glycidyl ester of a branched monocarboxylic acid, wherein the monocarboxylic acid has from 5 to 50 carbon atoms, wherein the hydrolysis stabilizer is present in the film in the form of its reaction product with at least some of the end-groups of the polyester; a process for making the same; and use of the film as a layer in a photovoltaic cell.

Abstract: A biaxially oriented polyester film including polyethylene terephthalate (PET) and at least one hydrolysis stabiliser selected from a glycidyl ester of a branched monocarboxylic acid, wherein the monocarboxylic acid has from 5 to 50 carbon atoms, wherein the hydrolysis stabiliser is present in the film in the form of its reaction product with at least some of the end-groups of the polyester; a process for making the same; and use of the film as a layer in a photovoltaic cell.

Abstract: A polyester film contains a polyester having an intrinsic viscosity (IV) in the range from 0.65 to 0.8 and an antioxidant. The polyester has an endothermic high temperature peak at a temperature of (A).degree.C. and an endothermic low temperature peak at a temperature of (B).degree.C., both peaks being measured by differential scanning calorimetry (DSC), and the value of (A-B) is in the range from 25.degree. C. to 50.degree. C. The polyester film is suitable for use an insulation film, exhibiting improved ageing properties.