What is a Solar Thermal Collector and When Should I Use Medium Temperature Collectors?

The most common medium temperature collectors are flat plate solar collectors. These collectors are popular for heating water and buildings as well as industrial heating operations. If people took advantage of this resource, it is reasonable to imagine a complete change in our fossil fuel dependence. For example, a residential hot water system costs approximately $5,000. Most states offer a major tax credit incentive that can reduce this capital expense by 50%. By using this system to heat residential water alone, most households will reduce their expense greatly and reduce their carbon foot print significantly. This application can be taken to another level when used to heat swimming pools or for commercial water heating.

Solar collectors are used to absorb heat through metal absorption panels attached to a metal frame. They have tubing that allows for liquid and air movement. While low temperature solar collectors account for a large percentage of solar thermal collector usage, medium temperature collectors are the best choice for certain conditions and are currently used for about 5% of projects. They have been increasing in popularity since 2001 and generally operate between 140 °F and 180°F. Different designs can accommodate different temperature ranges. High temperature collectors are rarely used and are generally in the experimental realm of electrical production on a large scale.

Many studies have been done to optimize the functions of solar thermal collectors. One important advancement is the use of double glazing on flat plate collectors. There is a large difference in temperature between the two plates of glass in a collector. Design modifications were necessary to cope with the intense mechanical strain resulting from the temperature differences. Inert gas is used as an insulator between the glass to keep heat from transferring. These features increase the efficiency of flat plate collectors for heating. As technology for medium temperature collectors improves, they will become more and more accessible and easy to maintain for the average home owner and business proprietor.