Evacuated Tubes- Simple Overview For Maryland Homeowners
This post is designed to be a very basic explanation of evacuated tube solar collectors. If you would like more technical details simply leave a comment or contact me by e-mail.
Evacuated tubes absorb solar energy converting it into heat for use in your household water heating. Many countries such as Canada, Germany, China and the U.S. have been using evacuated tube systems successfully for many years.
Each evacuated tube actually consists of two glass tubes an outer tube and inner tube. A special coating is applied to the inner tube to absorb more solar energy. As you can see from the picture (from Apricus) there is space between the outer 
and inner glass tubes. During manufacturing the air in this space is evacuated forming a vacuum. The number of evacuated tubes in a residential installation varies, but the typical residential Maryland installation consists of 30 evacuated tubes.
As you can see from the picture each evacuated tube is hollow. Inside this space is a small copper tube called a heat pipe. As the sun shines on the evacuated tube the copper pipe inside heats up. This heat is then transferred to your hot water storage tank heating your water.
A fully assembled evacuated tube solar water heater looks like this…
Just wanted to say thank you to everyone who has entered in the Maryland Solar Giveaway. So far, the response has been great. If you have any questions about your Giveaway Handbook or something else let me know by leaving a comment below.
Now, I am a huge fan of solar PV and truly believe if you are able to make the investment you will not be disappointed but, solar thermal systems or solar water heaters 
