After a while, do solar vacuum tube systems lose their vacuum?
There are a number of ways of making vacuum tube solar water heating systems. Many of our competitors use a fairly standard tube with a bonded joint between the tube and the copper pipe that takes the heated liquid. The glass and copper expand and contract at slightly different rates and this can cause cracking, loss of vacuum and a significant loss in performance.
More information can be found here: LaZer2 Solar Thermal Collectors