... saving, no bill cost for hot water usage; 2.Easy to install and operate; Solar water collector:solar collector is a device that absorbs thermal ... ;10,20,24,30,367.Hail resistance:25mm8.Coating of vacuum tube:ALN/AIN-SS/CU ModelTank CapacityHeat pipe or U ... (2 collector of 20 tubes)19/40ITM-500500L58X180030x1+20X1 (1 collector of 30 tubes and 1 collector for 20 tubes)16/36 Working principle: