Solar thermal collector is used to collect heat by absorbing sunlight. There are two types of collectors, simple collectors which are used to complement space heating in commercial and residential houses. Complex collectors use solar energy to heat water which and produce steam which is used to turn turbines to produce electricity. Collectors are generally used to convert solar energy into a more useful form of energy. A flat tube collector is a simple collector that is mostly used for heating water to reduce energy bills. Evacuated solar tube collectors on the other hand is a more complex collector has a vacuum surrounding the inside of the tube which serves to reduce loss of heat through convention and conduction. This makes it more efficient compared to the former flat plate collectors.
The efficiency of evacuated solar tube collectors is barely noticeable during the warm seasons unless when plenty of hot water is required especially for commercial purposes. They easily attain very high temperatures within a short time and may require special equipment to regulate heat to prevent over heating. Another advantage of this type of collector is that they have a larger surface area exposed to the sun therefore it is more efficient in transferring heat. The corrosion levels of evacuated tube collectors are very low compared to the flat plate tube collectors. They are quite expensive to buy but when they damage, it can easily be replaced at a low cost.