TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The content of organic peroxide in at least one of sealing sheets (11) and (12) with respect to 100 pts. wt. crosslinkable resin including organic peroxide, is 0.1-1.2 pts. wt. The content of aluminum element in ethylene-( alpha )-olefin copolymer is 10-500 ppm.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The polar group includes carboxyl group and/or ester group. At least one of sealing sheet (11) and (12) contains resin chosen from ethylene-based copolymer derived from ethylene-( alpha )-olefin copolymer, and ethylene and polar monomer copolymer including ethylene-based copolymer as crosslinkable resin. The content rate of structural unit in ethylene-( alpha )-olefin copolymer derived from ethylene is 80-90 mol%. The content rate of structural unit in ethylene-( alpha )-olefin copolymer derived from 3-20C ( alpha )-olefin is 10-20 mol%. This ethylene-based copolymer is chosen from ethylene-unsaturated carboxylic copolymer, ethylene-unsaturated carboxylic anhydride copolymer, ethylene-unsaturated-carboxylic-ester copolymer, ethylene-unsaturated carboxylic ester copolymer, ethylene-unsaturated glycidyl ester copolymer, ethylene-unsaturated glycidyl-ether copolymer, ethylene-unsaturated glycidyl ester copolymer, ethylene-unsaturated glycidyl ether copolymer, ethylene-unsaturated-carboxylic-ester copolymer and ethylene vinyl-ester copolymer. The ethylene and polar monomer copolymer are ethylene-vinyl acetate copolymer. The vinyl acetate content in the ethylene-vinyl acetate copolymer with respect to whole ethylene-vinyl acetate copolymer, is 15-47 wt.%. At least one of sealing sheets (11) and (12) contains 0.1-2 pts. wt. silane coupling agent, 0.005-5 pts. wt. ultraviolet absorber, optical stabilizer and/or heat-resistant stabilizer, and 0.05-5 pts. wt. crosslinking adjuvant. Preferred Properties: The ratio of volume-resistivity (ohm-cm) of heat-pressed sealing sheet (11) with respect to volume-resistivity (ohm-cm) of heat-pressed sealing sheet (12) is 1x 101 to 1x 1010. When the heat-pressed sealing sheet (12) is immersed in acetone at 23 for 1 hour, the absorption factor of acetone of heat-pressed sealing sheet with respect to weight heat-pressed sealing sheet (12) before being immersed in acetone, is 7-400 wt.%. The absorption factor of acetone of heat-pressed sealing sheet (12) is more than the absorption factor of acetone of heat-pressed sealing sheet (11). When the heat-pressed sealing sheet (12) is immersed in t-butanol at 30 degrees C for 1 hour, the absorption factor of t-butanol of heat-pressed sealing sheet with respect to the weight of heat-pressed sealing sheet (12) before being immersed in t-butanol, is 4-30 wt.%. The absorption factor of t-butanol of heat-pressed sealing sheet (12) is more than the absorption factor of t-butanol of heat-pressed sealing sheet (11). The volume resistivity of heat-pressed sealing sheet (11) is 1x 1013 to 1x 1018 (ohm-cm). The volume resistivity of heat-pressed sealing sheet (12) is 1x 108 to 1x 1016 (ohm-cm). The ethylene-( alpha )-olefin copolymer has MFR measured at 190 degrees C under load of 2.16 kg based on ASTM D1238 of 0.1-50 g/10 minutes, density based on ASTM D1505 of 0.865-0.884 g/cm3, and Shore A hardness based on ASTM D2240 of 60-85. The MFR of ethylene and polar monomer copolymer at 190 degrees C under a load of 2.16 kg based on ASTM D1238 is 5-50 g/10 minutes. Preferred Process: The sealing sheet (12) is positioned between back surface side protection component and solar cell element. The sealing sheets (11) and (12) are laminated and positioned between light-receiving surface side protection component and solar cell element.