TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The coloring agent is chosen from an organic pigment, a dye and/or inorganic filler. The inorganic filler is chosen from natural mica, synthetic mica, titanium oxide, aluminum oxide, calcium carbonate, talc, clay, a magnesium carbonate, kaolinite and/or diatomaceous earth particles. The content of acidic component in the sealing material is 8 wt. ppm or less.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The ethylene-( alpha )-olefin copolymer contains 80-90 mol% structural units derived from ethylene and 10-20 mol% structural units derived from 3-20C ( alpha )-olefin, with respect to 100 mol% sum total of structural units derived from ethylene and ( alpha )-olefin. The sealing material exists in a sheet form. The sealing material is solar cell backside sealing material further containing 1-30 pts. wt. coloring agent with respect to 100 pts. wt. ethylene-( alpha )-olefin copolymer, and is used for non-light-receiving surface side. The sealing layer is obtained by thermocompression-bonding the solar cell backside sealing material and a solar cell surface sealing material. Preferred Properties: The storage elastic modulus of the sealing material is (1x 105)-(7x 105) Pa, which is measured using the solid viscoelasticity analysis. The ethylene-( alpha )-olefin copolymer has melt flow rate of 0.1-8 g/10 minutes at 190 degrees C and load of 2.16 kg, when measured according to ASTM D1238, density of 0.865-0.884 g/cm3, measured according to ASTM D1505, and Shore A hardness of 60-85, measured according to ASTM D2240. The crosslinking sheet is obtained by cutting the sealing material into 0.5 mm (thickness)x 75 mm (length)x 60 mm (width) on 150 degrees C hot plate under reduced pressure for 3 minutes, and heating for 10 minutes. When the crosslinking sheet is subjected to long term reliability test in a humidity chamber at 85 degrees C and relative humidity of 85% for 2000 hours, and a yellow index of the crosslinking sheet before and after the test is set to YI1 and YI2, respectively, then the change rate of yellow index is less than 2, which is calculated using the relation: (YI1)-(YI2). The minimum value (Vb) of complex viscosity of the back surface sealing material is (4x 103)-(1x 106) Pa.second, when measured using solid viscoelasticity analysis in shear mode at 25-180 degrees C, frequency of 0.016 Hz and temperature increase rate of 3 degrees C/minute. The minimum value (Vs) of complex viscosity of the surface sealing material and the minimum value (Vb) satisfy the relation: log ((Vb)/(Vs))=(-2)-(3), when measured using solid viscoelasticity analysis in shear mode at 25-180 degrees C, frequency of 0.016 Hz and temperature increase rate of 3 degrees C/minute.