Scaling usually develops in the vacuum tube after using solar energy for 2-3 years. This will have a great impact on the absorption of solar heat. Because the scale on the inner wall of the vacuum tube has a great impact on heat transfer. Therefore, use a special solar cleaning agent or find someone to clean it. This will completely remove the tartar. I recommend Gekko, which is sold on Taobao.
It may be related to the internal structure and principle of the solar water heater, so that's it, I suggest you search it online. This is what I learned from others, hope it helps. Have you just installed solar? Because the installer used dish soap or other lubricants when installing the solar vacuum tube to make the vacuum tube easier and safer to install, so it will be slippery during the first few uses, but this situationtion will not be. used in the future