1)no water in evacuated collector tubes 2)evacuated collector tube with heat pipe 3)certificate:solar keymark,CE,SGS,SRCC Specifications:aluminum fin for Solar collector with copper heat pipea) dimension of vacuum tube: ø58*1800mm;ø70*1900mmb) quantity of tubes:15,18,20,24,30 tubesc) aluminum fin ,thicknness: 0.25mm ; length:1680mmd) hail resistance: diameter 25mme) manifold: red copper heat ...