contact me:himin24 at hotmail dot com 1.The vacuum tubes transform solar light into heat energy and then transfer the heat to the working media depending upon the fin and U-shaped copper pipe in the manner of thermal conduction. 2.There is no water in the vacuum tube,so the tube will not broken in the winter. 3.It has a smaller thermal loss,stronger adaptability and better performance of aging-resistant membranous layer. 4.Can operate with water pressure up to 0.6MPa 5.Can be combined with existing energy source 6.Storage do not need be installed above the collector 7.It can be combined with the architecture perfectly 8.Solar Keymark certified solar collector