Photovoltaic silicone encapsulant and photovoltaic module

In connection with a photovoltaic module comprising a photovoltaic cell having a front surface on which solar light is incident and a back surface, a front glass plate on the front surface, and a backsheet or back glass plate on the back surface,

• a silicone composition for encapsulating the photovoltaic cell comprising
• (A) 100 parts by weight of an organ containing at least two silicon-bonded alkenyl groups per molecule, represented by the average compositional formula (1)
• RaR′bSiO(4-a-b)/2 (1)
• wherein R is alkenyl, R′ is a substituted or unsubstituted monovalent hydrocarbon group of 1 to 10 carbon atoms free of aliphatic unsaturation, a and b are numbers in the range:
• 0<a≦2, 0<b<3, and 0<a+b≦3,
• (B) an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule, in such an amount that a molar ratio of silicon-bonded hydrogen in component (B) to silicon-bonded alkenyl in component (A) may be in a range of 0.4/1 to 2.5/1, and
• (C) a catalytic amount of an addition reaction catalyst,
• the silicone composition, when cured, having a water vapor permeability of at least 80 g/m2·day at 40° C. and a thickness of 1 mm.