Method of manufacturing solar cell module

1. A method of manufacturing a solar cell module comprising:

pressing a first silicone gel sheet provided on a sunlight receiving surface of a solar cell string and a second silicone gel sheet provided on an opposite side sunlight non-receiving surface of the solar cell string in a first vacuum to encapsulate the solar cell string with the first and second silicone gel sheets; and then

disposing a sunlight receiving surface side of the first silicone gel sheet on one surface of a transparent light receiving panel which is to be a sunlight incidence surface except an outer peripheral region thereof and disposing butyl rubber in a picture frame-like shape along the outer peripheral region of the one surface of the transparent light receiving panel which is to be a sunlight incidence surface where the first silicone gel coating is not formed, or disposing a sunlight non-receiving surface side of the second silicone gel sheet on one surface of a light non-receiving panel or back sheet which is to be a sunlight non-incidence side except an outer peripheral region thereof and disposing butyl rubber in a picture frame-like shape along the outer peripheral region of the one surface of the sunlight non-receiving panel or back sheet which is to be a sunlight non-incidence side where the second silicone gel coating is not formed and laying the light receiving panel and the light non-receiving panel or back sheet over each other with the silicone gel sheet-encapsulated solar cell string on the inside, and pressing them at 100 to 150° C. in a second vacuum for at least one minute but no longer than five minutes to press bond the light receiving panel and the light non-receiving panel or back sheet to each other through the butyl rubber, and

wherein the first silicone gel sheet and the second silicone gel sheet are a sheet of a silicone gel obtained by curing a silicone gel composition comprising:

(A) an organopolysiloxane having at least one silicon-bonded alkenyl group in one molecule and represented by the following average compositional formula (1):

R a R 1 b SiO (4-a-b)/2   (1)

wherein R is an alkenyl group, R 1 is independently an unsubstituted or substituted monovalent hydrocarbon group not having any aliphatic unsaturated bond, a is a positive number of 0.0001 to 0.2, b is a positive number of 1.7 to 2.2, and a+b is 1.9 to 2.4;

(B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule; and

(C) a platinum catalyst,

the silicone gel having a penetration of 30 to 200.

2. The method of manufacturing a solar cell module according to claim 1 , wherein the thickness of the first silicone gel sheet and the second silicone gel sheet is 200 to 1,000 μm.

3. The method of manufacturing a solar cell module according to claim 1 , wherein before the first vacuum the sunlight receiving surface side of the first silicone gel sheet or the sunlight non-receiving surface side of the second silicone gel sheet are subjected to a plasma irradiation treatment or an excimer beam irradiation treatment.