microns. The maximum allowed water vapor transmission rate shall be less than 2 g / m2 /day and shall have a Partial Discharge > / = 1500V DC 3. The front glass shall meet the following specifications: a. The facing glass must be Tempered, PV grade with Low iron and high transmission. b. The transmission shall be > 93 % c. Thickness shall be min 3.2 mm d. Textured to trap more light e. The glass shall have an Anti-reflective coating for the better transmission and light absorption. f. Tempered glass to meet the external load conditions