The mission of the Solar Thermal Center of Expertise in Sustainability (CXS) is to provide knowledge creation and sharing throughout USACE in the use of solar thermal technologies. Solar thermal refers to technologies that capture solar energy and convert it to thermal energy (heat). There are three types of solar thermal collectors (low-, medium-, or high-temperature). Low-temperature collectors are flat plates generally used to heat swimming pools. Medium-temperature collectors are also usually flat plates, but are used for heating water or air for residential and commercial use. High-temperature collectors concentrate sunlight using mirrors or lenses and are generally used for electric power production. Solar thermal energy generally transfers more of the sun resources into usable energy than solar photovoltaics (solar electric). Solar thermal systems can capture and transfer up to 60 percent of the sun's energy (insolation) into thermal energy while solar photovoltaics only captures and transfers 4 percent (solar film) to 16 percent (crystalline) of the sun energy into electric energy depending on the type of solar panels used. The Army has implemented several large scale solar thermal energy generation facilities, but the typical application continues to be hot water heating for vertical construction.