Sealing sheet for back surface of solar cell, and solar cell module

A sealing sheet for a back surface of a solar cell consisting of only one polyester film consisting of polyethylene terephthalate homopolymer as the polymeric component,

• wherein
• the polyester film is composed of (a) layer A and layer B or (b) layer A, layer B, and layer C, wherein the layer A, the layer B, and the layer C are laminated in this order,
• the polyester film has a whiteness of 50 or more, an average reflectance of 50 to 95% in the range of a wavelength of 400 to 800 nm, an acid value of polyester constituting the polyester film of 1 to 50 eq/ton, and a thickness of 150 to 380 μm,
• the polyester film has a multilayer structure in which the layer A is disposed as an outermost layer opposite to the back surface of the solar cell,
• the thickness of the layer A is 3 to 30% of the thickness of the whole polyester film,
• the thickness of the layer B is 20% or more of the thickness of the whole polyester film,
• the content of inorganic fine particles in the whole polyester film is 0.5 to 2.7% by mass,
• the layer B does not contain voids,
• layer A is a polyester resin layer in which the content of the inorganic fine particles is 18 to 35% by mass,
• layer B is a polyester resin layer in which the content of the inorganic fine particles is 0 to 2% by mass, which is the smallest among the contents of the inorganic fine particles in the layer A, the layer B and the layer C, and
• layer C is a polyester resin layer in which the content of the inorganic fine particles is 0.4 to 10% by mass.