GLASS SUBSTRATE FOR CdTe SOLAR CELL, AND SOLAR CELL

A glass substrate for a CdTe solar cell, comprising, in terms of mol % on a basis of following oxides:

• from 60 to 75% of SiO2;
• from 1 to 7.5% of Al2O3;
• from 0 to 1% of B2O3;
• from 8.5 to 12.5% of MgO;
• from 1 to 6.5% of CaO;
• from 0 to 3% of SrO;
• from 0 to 3% of BaO;
• from 0 to 3% of ZrO2;
• from 1 to 8% of Na2O;
• and
• from 2 to 12% of K2O,
• wherein MgO+CaO+SrO+BaO is from 10 to 24%,
• Na2O+K2O is from 5 to 15%,
• MgO/Al2O3 is 1.3 or more,
• (2Na2O+K2O+SrO+BaO)/(Al2O3+ZrO2) is 3.3 or less,
• Na2O/K2O is from 0.2 to 2.0,
• Al2O3≧−0.94MgO+11, and
• CaO≧−0.48MgO+6.5,
• wherein the glass substrate has a glass transition temperature of 640° C. or higher, an average coefficient of thermal expansion within a range of from 50 to 350° C. of from 70×10−7 to 90×10−7/° C., a temperature (T4), at which a viscosity reaches 104 dPa·s, of 1,230° C. or lower, a temperature (T2), at which a viscosity reaches 102 dPa·s, of 1,650° C. or lower, a relationship between the T4 and a devitrification temperature (TL) of T4-TL≧−30° C., and a density of 2.7 g/cm3 or less.