All air is pumped out of each evacuated solar tube collector to create a vacuum. A vacuum is one of the best insulators known. Creating a well insulated evacuated solar tube collector is essential; it helps keep the tubes from cooling down in cold weather conditions. After absorbing radiation from the sun, the collector converts the radiation into heat. Heat from the evacuated solar tube collectors warms the heat transfer fluid which is then brought to the heat storage cyclinder.
Each evacuated solar tube collector is made out of 10 to 30 different individual tubes. They can be direct flow evacuation tubes or so-called heat pipes (the heat transfer fluid does not pass through the pipes).
Advantages and disadvantages of the evacuated tube collector
Due to its superior insulation, the evacuated tube collector is much more efficient than the flat plate collector. You need less solar collectors to achieve a certain energy input - or get more energy from the same space.
But while an evacuated tube collector is about 10 to 15 percent more efficient than a flat collector, it is also more expensive. Customers should carefully consider how much solar energy they will really need to suit their purposes. In many of cases, an array of flat plate collectors might be enough to do the job.
The positioning of evacuated solar tube collectors is vital in maximizing their efficiency. A flat layout is very ineffective, as the tubes will receive less solar radiation.
Experienced solar installiers will help you to plan and install evacuated solar tube collectors for your solar water heating system.