NOVELTY - Polymeric optically transparent encapsulant composition comprises: at least one olefinic co-polymer having a glass transition temperature of less than or equal to 20 degrees C and a 10% secant tensile modulus of less than or equal to 16000 psi; at least one UV light absorber having a chemical structure with no hydroxyl group at an ortho position of an aromatic ring with respect to an aromatic carbonyl group, a triazole group, or a triazine group; and at least one adhesion promoter.    USE - The polymeric optically transparent encapsulant composition is useful in electrical energy generating device (claimed) and for encapsulating photovoltaic modules.    ADVANTAGE - The polymeric optically transparent encapsulant composition: optimizes the efficiency of photovoltaic devices while minimizing the deleterious effects of UV radiation on the polymeric encapsulant; exhibits long-term weathering stability without compromising the optimum efficiency of the underlying solar cells; and improves the optical properties.    DETAILED DESCRIPTION - Polymeric optically transparent encapsulant composition comprises: at least one olefinic co-polymer having a glass transition temperature of less than or equal to 20 degrees C and a 10% secant tensile modulus of less than or equal to 16000 psi; at least one UV light absorber having a chemical structure with no hydroxyl group at an ortho position of an aromatic ring with respect to an aromatic carbonyl group, a triazole group, or a triazine group; and at least one adhesion promoter, where the polymeric optically transparent encapsulant is (a1) a solar energy weighted transmittance at wavelengths of light 350-1200 nanometers greater than or equal to 85%, and (b1) an UV light cutoff less than or equal to 345 nanometers. An INDEPENDENT CLAIM is included for electrical energy generating device comprising (a) an upper protective layer, (b) a middle photovoltaic-element layer, (c) a lower substrate layer, and (d) the encapsulant layer.