NOVELTY - A solar cell back surface protection sheet has weather-resistant resin layer (1) laminated on plastic film (3) through easily adhesive resin layer (2). The weather-resistant resin layer is obtained using weather-resistant resin composition containing acryl-type copolymer (A) having hydroxyl group, and polyisocyanate compound (B1). The ratio of isocyanate group in the compound (B1) is 0.1-5 times the total of the functional groups which reacts with the isocyanate group in the copolymer (A). The acryl-type copolymer (A) has glass transition temperature of 0-90 degrees C.    USE - Back surface protection sheet is used for solar cell modules (claimed).    ADVANTAGE - The back surface protection sheet is economical, and has suppressed generation of cracks, excellent abrasion resistance, solvent resistance, long-term outdoor weather resistance, long-term heat-and-moisture resistance, and water vapor barrier property.    DETAILED DESCRIPTION - A solar cell back surface protection sheet has weather-resistant resin layer laminated on plastic film through easily adhesive resin layer. The weather-resistant resin layer is obtained using weather-resistant resin composition containing acryl-type copolymer (A) having hydroxyl group, and polyisocyanate compound (B1). The ratio of isocyanate group in the polyisocyanate compound (B1) is 0.1-5 times the total of the functional groups which reacts with the isocyanate group in the acryl-type copolymer (A). The acryl-type copolymer (A) has glass transition temperature of 0-90 degrees C, weight average molecular weight of 30000-250000, and hydroxyl value of 20-150 mg potassium hydroxide/g. The copolymer (A) is a copolymer having aromatic ring content of 50 wt.% or less. The easily adhesive resin layer is formed using easily adhesive resin composition containing polyether urethane-type copolymer (D) having hydroxyl group, and polyisocyanate compound (B2). The ratio of isocyanate group in the compound (B2) is 0.1-10 times with respect to hydroxyl group. The polyether urethane-type copolymer (D) is obtained by reacting polyalkylene glycol and 3-4C diisocyanate. The copolymer (D) has equivalent ratio (NCO/OH) of isocyanate and hydroxyl group of 0.7-1, and weight average molecular weight of 20000-150000. INDEPENDENT CLAIMS are included for the following:    (1) manufacture of solar cell back surface protection sheet, which involves forming and hardening easily adhesive resin layer and weather-resistant resin layer on one side of the plastic film, in order; and    (2) solar cell module, which has solar cell surface-protection layer on the light-receiving surface side of the solar cell, sealing material layer on the light-receiving surface side of the solar cell, solar cell, and sealing agent layer on non-light-receiving surface side of the solar cell. The non-light-receiving surface side of sealing agent layer consists of back surface protection sheet, such that the weather-resistant resin layer is located on the opposite side to the non-light-receiving surface side.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the solar cell back surface protection sheet.    Weather-resistant resin layer (1)    Easily adhesive resin layer (2)    Plastic film (3)    Adhesive bond layer (4)