1. the endothermic effect is better 2.improve the collection efficiency Solar radiation wavelength range of about 0.15-4 microns, can be divided into ultraviolet, infrared region, and visible light, solar energy radiation is mainly in the 0.16-2.0 microns, old-fashioned vacuum tube directly absorption of solar radiation in the wavelength range 0.2-0.5 microns, Zijin frequency vacuum tube ...