SOLAR CELL
The present invention provides a solar cell having high photovoltaical conversion efficiency and being excellent in the light transmissivity and weather resistance such as solarization resistance. The present invention relates to a solar cell comprising a double tube composed of two glass tubes differing in the diameter and a photovoltaic conversion layer formed between the two glass tubes, the double tube being sealed at both ends of a part in which the photovoltaic conversion layer is formed, wherein at least one of the two glass tubes is composed of a glass comprising, in mass % based on the oxides, from 60 to 75% of SiO 2 , from 4 to 10% of Al 2 O 3 , from 0 to 5% of B 2 O 3 , from 0 to 5% of MgO, from 0.5 to 5% of CaO, from 0 to 0.5% of SrO, from 0 to 11% of BaO, from 10 to 16% of Na 2 O, from 0 to 10% of K 2 O, and from 0.5 to 10% of ZrO 2 .
1 . A solar cell comprising a double tube composed of two glass tubes differing in the diameter and a photovoltaic conversion layer formed between the two glass tubes, the double tube being sealed at both ends of a part in which the photovoltaic conversion layer is formed,
wherein at least one of the two glass tubes is composed of a glass comprising, in mass % based on the oxides, from 60 to 75% of SiO 2 , from 4 to 10% of Al 2 O 3 , from 0 to 5% of B 2 O 3 , from 0 to 5% of MgO, from 0.5 to 5% of CaO, from 0 to 0.5% of SrO, from 0 to 11% of BaO, from 10 to 16% of Na 2 O, from 0 to 10% of K 2 O, and from 0.5 to 10% of ZrO 2 .
2 . The solar cell according to claim 1 , wherein a total content of Al 2 O 3 and ZrO 2 in the glass is from 5 to 15%.
3 . The solar cell according to claim 1 , wherein a content of Fe 2 O 3 in the glass is 0.06% by outer percentage or less based on the total of other components (exclusive of Sb 2 O 3 in the case where Sb 2 O 3 is contained).
4 . The solar cell according to claim 1 , wherein the glass does not substantially comprise CeO 2 .
5 . The solar cell according to claim 1 , wherein a glass transition temperature Tg of the glass is 530° C. or more.
6 . The solar cell according to claim 1 , wherein an average linear expansion coefficient of the glass at 50 to 300° C. is from 70×10 −7 to 110×10 −7 /° C.
7 . The solar cell according to claim 1 , wherein a temperature at which a melt viscosity of the glass is 10 2 dPa·s is 1,550° C. or less.
8 . The solar cell according to claim 1 , wherein an average transmittance of the glass at a wavelength of 450 to 1,000 nm is 90% or more in terms of thickness of 1 mm.
9 . The solar cell according to claim 1 , wherein a transmittance of the glass at a wavelength of 400 nm is 89% or more in terms of thickness of 1 mm.
10 . The solar cell according to claim 1 , wherein a density of the glass is 2.6 g/cm 3 or less.
11 . The solar cell according to claim 1 , wherein when the glass is held in a water vapor atmosphere at 120° C. under 0.2 MPa for 20 hours, an amount of an alkali metal element deposited on a surface of the glass is 200 nmol/cm 2 or less.
12 . The solar cell according to claim 1 , wherein an electrical conductivity of the glass at 300° C. is 2×10 −6 S/cm or more.
13 . A glass tube for a solar cell, which is used as at least one of two glass tubes of a solar cell comprising a double tube composed of two glass tubes differing in the diameter and a photovoltaic conversion layer formed between the two glass tubes, the double tube being sealed at both ends of a part in which the photovoltaic conversion layer is formed, and which is composed of a glass comprising, in mass % based on the oxides, from 60 to 75% of SiO 2 , from 4 to 10% of Al 2 O 3 , from 0 to 5% of B 2 O 3 , from 0 to 5% of MgO, from 0.5 to 5% of CaO, from 0 to 0.5% of SrO, from 0 to 11% of BaO, from 10 to 16% of Na 2 O, from 0 to 10% of K 2 O, and from 0.5 to 10% of ZrO 2 .
14 . The glass tube for a solar cell according to claim 13 , wherein when the glass is held in a water vapor atmosphere at 120° C. under 0.2 MPa for 20 hours, an amount of an alkali metal element deposited on a surface of the glass is 180 nmol/cm 2 or less.
15 . The glass tube for a solar cell according to claim 13 , wherein an electrical conductivity of the glass at 300° C. is 2×10 −6 S/cm or more.