... 94~0.96 emittance:0.04~0.06 Solar collector tube introductionFeature:1 Quality warranty :15 years2. ... 15 years.Absorptance of three high efficiency solar vacuum tube increased by 12%, and launch reduced ... super absorbing, heat loss less, warming faster. Efficient tube, the super absorbing, thermal efficiency is high, ... , not aging, discoloration. High efficiency evacuated solar collector tubes