... EN12975, Solar key mark,SRCC,CE,ISO. 2. 0.68~0.73 premium conversion Vacuum tube solar collectors -- Keymark/ ... .90-0.93(AM1.5) / 0.93-0.96(AM1.5)Emission ratio0.05-0.075(800C±50C) / 0.04-0.06( ... ².C/KWAverage heat loss coefficientULT=0.6~0.7W/(M2.0C) / ULT=0.4~0.6W/(M2.0C)Resistant Hail≤ ... :Stronger galvanized steel / Stainless steel/aluminium alloyBracket angle:0,18,22,38,45 optional, pitched roof, flat ...