Evacuated Tube Solar Water Heater

A solar water heater consists of a collector to collect solar energy and an insulated storage tank to store hot water. Based on the collector system, solar water heaters can be of two types. The first one being solar water heaters based on flat plate collectors in which the solar radiation is absorbed by using flat plate collectors instead of an insulated outer metallic box coveredby glass sheet.

The second type being based on evacuated tube collectors in which the collector is made of double layer borosilicate glass tubes evacuated for providing insulation. This kind of solar water heater offers great efficiency compared to other solar water heaters.

The efficiency of evacuated tube solar water heater is more than 90%,it means that is converts more that 90% of the sunlight hitting its surface to heat that can be used to heat water.The evacuated eube solar water heater is also very cheap to renew.The evacuated tubes are made from ultra strong glass and heat resisted Pyrex with a double wall construction.

The inner tube of the glass is coated on its outer surface with a absorbant coating and on its inner surface with a reflective coating.Inside each tube ,all the air present is removed making a vacuum and a copper heat pipe is located through the center of the tube.Most of the heat from the sun is absorbed by this sealed heat pipe which contains an anti-freeze type liquid.

As the heat rises,hot vapours from the antifreeze rise up to the top of the heat pipe where its copper connects with a header pipe throught which more antifreeze flows.This hot antifreeze then pumped through pipes inside the hot water tank with the end result that thte water gets hotter and the antifreeze cooler.The antifreeze then continues around the system and back out to the solar water heater to be reheated.The copper at the tip of the heat can reach very hight degrees easily heating awter to around 90 degrees celcius.

This Entire set up is completely sealed and doesnt need much maintenance. The advantage of using this type of solar water heater is that they even work during adverse climatic condition unlike Flat Plate Solar Collectors.The vacuum prevents the heat tube from being cooled much by the ambient temperature which can be well below freezing, and so winter sun can easily heat water to 50+ degrees even in the depths of the coldest season.

Even if it is very cloudy and very cold, enough sunlight gets through to keep the tubes well above freezing and so they will be still be pre-heating the water which can then be heated further by a standard immersion heater or gas burner reducing the costs of heating the water. The fitting of this solar water heating system is not a tough task,it can be carried out by anyone with a little bit of knowledge and basic plumbing skills.The low cost and maintenance make the Evacuated Tube Solar Water Heater the preferred choice.