Evacuated Tube Collector (ETC) Solar Water Heater

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In this Evacuated Tube Collector (ETC) Solar Water Heater, An evacuated tube acts as an absorber in this type of solar water heater. Each evacuated tube consists of two glass tubes with a vacuum in between, which acts as an excellent insulator. The incident solar radiation falling on the tube passes through the outer transparent tube and strikes the inner tube (having a dark absorbing coating). It absorbs the heat energy and then passes it to the cold water flowing in the tube.