NOVELTY - An insulating backboard has a first adhesive layer (2) bonded on a surface of a side of a structure enhancement layer (1). A second adhesive layer (3) is bonded on the surface of another side of the structure enhancement layer. A first weatherproof layer (4) is bonded on a surface of the first adhesive layer backing against the side of the structure enhancement layer. A second weatherproof layer (5) is bonded on the surface of the second adhesive layer backing against the former side of the structure enhancement layer. The enhancement layer is made of polyethylene glycol terephthalate.    USE - Insulating backboard for a solar energy photovoltaic battery.    ADVANTAGE - The first and second weatherproof layers and the structure enhancement layer have better compatibility. The backboard integrally improves electric insulating performance and weather resistance. The backboard has better vapor permeation resistance, hydrolytic resistance and uvioresistant resistance. The service life of the backboard is prolonged.    DETAILED DESCRIPTION - An insulating backboard has a structure enhancement layer, a first adhesive layer and a second adhesive layer, where the first adhesive layer is bonded on a surface of a side of the structure enhancement layer. The second adhesive layer is bonded on the surface of another side of the structure enhancement layer. A first weatherproof layer is bonded on a surface of the first adhesive layer backing against the side of the structure enhancement layer. A second weatherproof layer is bonded on the surface of the second adhesive layer backing against the former side of the structure enhancement layer. The structure enhancement layer is made of polyethylene glycol terephthalate. The first and second adhesive layers are made of adhesive of the polyethylene glycol terephthalate. The first and second weatherproof layers are made of polyvinylidene chloride.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of an insulating backboard.    Structure enhancement layer (1)    Adhesive layers (2, 3)    Weatherproof layers (4, 5)