SOLAR CELL
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 70% of SiO 2 , from 4 to 10% of Al 2 O 3 , from 0 to 3% of B 2 O 3 , from 0 to 4% of MgO, from 2 to 9% of CaO, from 1 to 10% of SrO, from 0 to 2% of BaO, from 10 to 16% of Na 2 O, from 0 to 5% of K 2 O, from 0 to 2% of ZrO 2 and from 0 to 2% of CeO 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 70% of SiO 2 , from 4 to 10% of Al 2 O 3 , from 0 to 3% of B 2 O 3 , from 0 to 4% of MgO, from 2 to 9% of CaO, from 1 to 10% of SrO, from 0 to 2% of BaO, from 10 to 16% of Na 2 O, from 0 to 5% of IC 2 O, from 0 to 2% of ZrO 2 and from 0 to 2% of CeO 2 .
2 . The solar cell according to claim 1 , wherein out of the two glass tubes of the double tube, the glass tube having a larger diameter is composed of the glass, and the glass comprises 0.2% or more of CeO 2 .
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 comprises CeO 2 and does not substantially comprise Sb 2 O 3 .
5 . The solar cell according to claim 1 , wherein the glass comprises Sb 2 O 3 and does not substantially comprise CeO 2 .
6 . The solar cell according to claim 1 , wherein a softening point of the glass is 705° C. or more.
7 . The solar cell according to claim 1 , wherein a strain point of the glass is 490° C. or more.
8 . The solar cell according to claim 1 , wherein a temperature at which a viscosity of the glass is 10 2 dPa·s is 1,550° C. or less.
9 . 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.
10 . 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 nm.
11 . The solar cell according to claim 1 , wherein when a glass plate which has a thickness of 1 mm and is composed of the glass is irradiated with light of a high-pressure mercury lamp of 400 W for 300 hours from a distance of 15 cm, a decrease in the transmittance at a wavelength of 400 nm is 4% or less.
12 . 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 180 nmol/cm 2 or less.
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 70% of SiO 2 , from 4 to 10% of Al 2 O 3 , from 0 to 3% of B 2 O 3 , from 0 to 4% of MgO, from 2 to 9% of CaO, from 1 to 10% of SrO, from 0 to 2% of BaO, from 10 to 16% of Na 2 O, from 0 to 5% of K 2 O, from 0 to 2% of Zr0 2 and from 0 to 2% of CeO 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.