99600c1d_Collector___Solar_Water_Heater__Evacuated_Tube_Collector
[S.No] 5 [Flat Plate Collector] Emissivity is high. [Evacuated Tube Collector] 
Emissivity is low.
Comparison between Evacuated Tube Collector & Flat Plate Collector - Solar Water Heater
Evacuated Tube Collector