Facts about Solar Thermal Energy Systems
How Solar Thermal Energy Works
Solar thermal energy is a technology that harvests solar energy to use as heat. The sun’s radiation is converted to heat by using solar collectors, and that heat is then transferred to water. Solar thermal systems are used domestically and commercially to heat hot water used in cooking, showers, faucets, laundry and process heat. They are the clean-energy equivalent to gas-fueled water heaters.
Solar Thermal Collector
Radiation from the sun is absorbed by solar thermal collectors, which contain water tubes inside. The water inside the tubes are heated, which then flows through a solar controller and into an insulated storage tank. The solar controller reads the temperature at the solar collector and inside the storage tank. When the storage tank requires more heat, the controller activates a pump, which circulates hot water from the solar collector into the storage tank.
Solar Thermal Energy Storage
Solar thermal storage tanks can have 2 to 3 inches of foam insulation around a steel tank. Because of insulation, water can remain hot in a storage tank for up to three days without the water receiving energy from the sun. Some storage tanks use a heat exchanger to transfer water from the hot water tubes to the water inside the tank. Some storage tanks also come with a backup electrical element to provide heating in case of an emergency.
Advantages and Disadvantages of Solar Thermal Energy
There are many advantages to using solar thermal energy: inexpensive or free water heating, environmental friendliness, very low maintenance, use of renewable energy, the government will help you pay for them, and using solar water heating has 4 to 5 times the energy effectiveness of using photovoltaic (PV) panels at a fraction of the cost. Comparing them to solar PV systems, solar thermal systems are more energy efficient and cost less so the return on investment is better.
The two major disadvantages of solar thermal energy are the heating inconsistency due to the seasonal variation of solar radiation, and the higher initial cost over traditional gas-fueled and electric water heaters.