An Evacuated Tube Collector (ETC) is a solar water heating system that is based on efficient solar collector technology. It uses conductive glass tubes to absorb heat from the sun, which is then transferred to the water or other circulating fluids.

An ETC consists of a number of glass tubes that are made of borosilicate or soda lime glass. These sealed glass tubes have copper rods within them that are thermally conductive. The glass tubes are supported by a frame and are arranged in a parallel pattern. Each tube is made up of a thick outer tube and a thin inner tube. The air between the inner and outer tubes is removed to create a vacuum. The name, “evacuated tube,” comes from this evacuation of air. The vacuum gives the system an insulating effect, making heat loss difficult. This makes an ETC solar water heater produce higher fluid temperatures when compared to other solar water heaters like the FPC (Flat Plate Collector).

The tubes are coated in such a way that the coating absorbs heat while preventing heat loss. The copper rods with their evacuated tubes are connected to a heat exchanger where cold water flows in to get heated by the evacuated tube and flows out to the insulated storage tank as hot water. This hot water can be used even after the sun has taken leave for the day.

ETC solar water heaters are more modern and more efficient when compared to their peers because:

• They are space savers because of their tubular structure and because they are not filled with large amounts of water.
• Because of the cylindrical shape of the tube, the sunlight is always perpendicular to the tube. This makes the collectors perform efficiently even during early mornings, evenings, or cloudy days when sunlight is minimal.
• Because the vacuum does not support heat loss, an ETC solar water heater can heat water to fairly higher temperatures on days when the atmospheric temperature is low, making hot water available to you on cold days as well.

ETC solar water heaters can be used for domestic and industrial purposes. Arun Solar is one of the top ETC solar manufacturers in Karnataka and we can help you assess your needs and customize your ETC solar water heater for you.