solar system specification: Absorb rate: 93%, thermal radiation rate: 6 %( 100) solar system specification:1. Whole glass vacuum tubes adopt super hard borax and silica glass; 2. Absorb rate: 93%, thermal radiation rate: 6 %( 100) 3. Temperature when exposed to sun without water: 250C, 2.5hours to boiling if using single tube; 4. Resist 25mm hail, using life can last 15 years solar system