Patent ID: 8647995

Claim:
A photovoltaic device, comprising a glass consisting essentially of in weight percent: 50 to 72 percent SiO 2 ; greater than 15 to 25 percent Al 2 O 3 ; 0 to 10 percent B 2 O 3 ; 10 to 25 percent total M 2 O; greater than 0 to 25 percent total RO; wherein M is an alkali metal selected from Na, K, Li, Rb, and Cs, wherein the glass comprises at least 9 weight percent Na 2 O, and wherein R is an alkaline earth metal selected from Mg, Ca, Ba, and Sr, wherein the glass comprises less than 4 weight percent K 2 O, the glass is in the form of a sheet and is a substrate or superstate; and an active photovoltaic medium adjacent to the substrate or supersrate, wherein the glass has a strain point of 535° C. or greater, a coefficient of thermal expansion of 50 ×10 −7 or greater, and a liquidus viscosity of 130,000 poise or greater.