It is best to fill it with water. Reason 1: Filling it with water can increase the weight of the solar energy and prevent it from being blown away by strong winds. Second reason: If the solar energy contains water, the temperature will not be too high (lower than 100 degrees Celsius and it can reach 200-300 degrees without water), which will reduce the aging speed of the ring made of solar energy sealing rubber. Third reason: If there is water in the vacuum tube, the temperature will be low, which can reduce the attenuation speed of the film layer.
Of course, if there is water, the scale will also increase, but the amount will not be large.