A method for producing a composite film for a superstrate thin-film solar cell, said method comprising: forming a transparent conductive coating by using a wet coating method to apply a transparent conductive film composition to a photovoltaic layer of a superstrate thin-film solar cell that is laminated on a substrate with a first transparent conductive film disposed therebetween; forming a conductive reflective coating by using a wet coating method to apply a conductive reflective film composition to said transparent conductive coating; and subsequently baking said substrate having said transparent conductive coating and said conductive reflective coating formed thereon at a temperature within a range from 130 to 400°C, thereby forming two layers composed of a second transparent conductive film having a thickness of 0.03 to 0.5 μm and a conductive reflective film having a thickness of 0.05 to 2.0 μm, wherein said transparent conductive film composition contains conductive oxide microparticles, and either one or both of a polymeric binder and a non-polymeric binder that cure upon heating, said conductive reflective film composition contains metal nanoparticles, and one or more additives selected from the group consisting of organic polymers, metal oxides, metal hydroxides, organometallic compounds and silicone oils, said metal nanoparticles include at least 75% by mass of silver nanoparticles, an amount of said additives is in a range from 0.1 to 20% of a mass of said silver nanoparticles in said metal nanoparticles, said organic polymer is one or more polymers selected from the group consisting of polyvinylpyrrolidone, polyvinylpyrrolidone copolymers and water-soluble celluloses, said metal oxide is selected from oxides or composite oxides containing at least one metal selected from the group consisting of aluminum, silicon, titanium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum, tin, indium and antimony, said metal hydroxide is selected from hydroxides containing at least one metal selected from the group consisting of aluminum, silicon, titanium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum, tin, indium and antimony, said organometallic compound is selected from metal soaps, metal complexes and metal alkoxides of at least one metal selected from the group consisting of silicon, titanium, aluminum, antimony, indium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum and tin, said silicone oil is selected from straight silicone oils and modified silicone oils, and said wet coating method is one of a spray coating method, a dispenser coating method, a spin coating method, a knife coating method, a slit coating method, an inkjet coating method, a screen printing method, an offset printing method or a die coating method. forming a transparent conductive coating by using a wet coating method to apply a transparent conductive film composition to a photovoltaic layer of a superstrate thin-film solar cell that is laminated on a substrate with a first transparent conductive film disposed therebetween; forming a conductive reflective coating by using a wet coating method to apply a conductive reflective film composition to said transparent conductive coating; and subsequently baking said substrate having said transparent conductive coating and said conductive reflective coating formed thereon at a temperature within a range from 130 to 400°C, thereby forming two layers composed of a second transparent conductive film having a thickness of 0.03 to 0.5 μm and a conductive reflective film having a thickness of 0.05 to 2.0 μm, wherein said transparent conductive film composition contains conductive oxide microparticles, and either one or both of a polymeric binder and a non-polymeric binder that cure upon heating, said conductive reflective film composition contains metal nanoparticles, and one or more additives selected from the group consisting of organic polymers, metal oxides, metal hydroxides, organometallic compounds and silicone oils, said metal nanoparticles include at least 75% by mass of silver nanoparticles, an amount of said additives is in a range from 0.1 to 20% of a mass of said silver nanoparticles in said metal nanoparticles, said organic polymer is one or more polymers selected from the group consisting of polyvinylpyrrolidone, polyvinylpyrrolidone copolymers and water-soluble celluloses, said metal oxide is selected from oxides or composite oxides containing at least one metal selected from the group consisting of aluminum, silicon, titanium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum, tin, indium and antimony, said metal hydroxide is selected from hydroxides containing at least one metal selected from the group consisting of aluminum, silicon, titanium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum, tin, indium and antimony, said organometallic compound is selected from metal soaps, metal complexes and metal alkoxides of at least one metal selected from the group consisting of silicon, titanium, aluminum, antimony, indium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum and tin, said silicone oil is selected from straight silicone oils and modified silicone oils, and said wet coating method is one of a spray coating method, a dispenser coating method, a spin coating method, a knife coating method, a slit coating method, an inkjet coating method, a screen printing method, an offset printing method or a die coating method.