Abnormal. If it's a sunny day, your solar energy hasn't been changed privately. According to the original factory production configuration, the ratio of the lighting area of the solar vacuum tube to the water volume of the water tank. is calculated. If it's sunny all day, the water temperature will increase at least from morning to evening. At around 50 degrees, your solar energy will only increase by 8 degrees. The temperature indication on the instrument may be incorrect, or. the water supply does not stop and the water temperature does not rise, or your solar vacuum tube breaks down and the heat absorption efficiency is too low
I hope to adopt thank you