... . This system consists of solar vacuum tube, heat pipe, water tank, stand, P/T valve. 2. It is very high efficiency that ... .4mm SUS304-2B .3. Stand: galvanized steel with painting,or Aluminium alloy, or stainless steel.4. Water tank heat insulation layer: 50 ... ~60 mm polyurethane foam.5. Stand angle: 15 degree, 20 degree ...