99600c1d_Collector___Solar_Water_Heater__Evacuated_Tube_Collector
[S.No] 6 [Flat Plate Collector] Freezing of water will take place at high altitude causing damage to the collector. [Evacuated Tube Collector] 
Satisfactory performance even in extreme cold condition (-18 deg. C)
Comparison between Evacuated Tube Collector & Flat Plate Collector - Solar Water Heater
Evacuated Tube Collector