NOVELTY - Photovoltaic backplate having high partial discharge voltage, comprises olefin copolymer layer, weatherable adhesive layer, polyester base layer and weatherable layer, which are bonded together. The olefin copolymer layer is composed of first main resin, inorganic filler, ultraviolet absorber, light stabilizer, thermal oxidative aging agent and crosslinking agent. The weatherable adhesive layer is composed of second main resin (fluororesin, acrylic resins and/or alkyd resin), inorganic filler, ultraviolet absorber, light stabilizer, thermal oxidative aging agent, curing agent and catalyst.    USE - Used as photovoltaic backplate having high partial discharge voltage.    ADVANTAGE - The backplate: has good moisture barrier properties, and excellent mechanical strength and outdoor durability; and is suitable for large photovoltaic modules.    DETAILED DESCRIPTION - Photovoltaic backplate having high partial discharge voltage, comprises olefin copolymer layer, weatherable adhesive layer, polyester base layer and weatherable layer, which are bonded together. The olefin copolymer layer is composed of 80-99 wt.% first main resin, 0-20 wt.% inorganic filler, 0.001-0.1 wt.% ultraviolet absorber, 0.001-0.1 wt.% light stabilizer, 0.001-0.1 wt.% thermal oxidative aging agent and 0.01-5 wt.% crosslinking agent, the first main resin is obtained by copolymerizing ethylene with propylene, butene, heptene and/or octene monomers, the weatherable adhesive layer is composed of 60-90 wt.% second main resin, 0-30 wt.% inorganic filler, 0-0.1 wt.% ultraviolet absorber, 0-0.1 wt.% light stabilizer, 0-0.1 wt.% thermal oxidative aging agent, 1-10 wt.% curing agent, 0.01-1 wt.% catalyst, the second main resin is composed of fluororesin, acrylic resins and/or alkydresin, the polyester base layer is composed of 85-95 wt.% third main resin, 0-10 wt.% inorganic filler, 0.1-8 wt.% hydrolytic stabilizers, 0.01-3 wt.% thermal oxidative aging agent, the third main resin is composed of poly(ethylene glycol terephthalate), poly(butylene glycol terephthalate), poly(ethylene glycol naphthalate) and/or poly(butylene glycol naphthalate), the weatherable layer is composed of 70-90 wt.% fourth main resin, 5-20 wt.% inorganic filler, 3-15 wt.% curing agent and 0.01-1 wt.% catalyst, and the fourth main resin is a fluororesin.    DESCRIPTION OF DRAWING(S) - The diagram shows cross-sectional view of photovoltaic backplate having high partial discharge voltage.