Solar thermal technologies use the sun’s power to heat air or water. The two types of solar thermal technology can be either active or passive. Active means that the system requires a fan or a pump to work.
In passive solar technology, the only product used is rays from the sun. This is useful for homes in heating and cooking. For homes, windows facing the south will let the sun’s light get inside. Any dense dark object that can collect and hold heat, such as bricks or tile, is placed where the sun shines inside the house. It will change the light energy into heat and store a portion of the heat for when the house gets cold.
Active solar technology uses collectors that incorporate a transparent cover and dark absorbing surface with a pump to move liquids or air through it. These collectors are often placed on roofs where they can get the most sun and absorb a lot of heat. The air system can help to heat a house or other building while the liquid system would produce hot water for domestic or industrial use, including space heating through a radiant floor heating system. The liquid systems use a food-safe antifreeze or a drainback design because without use of one of these systems, water could freeze, expand and then break the pipes or collector. A heat exchanger, where the hot heat transfer fluid is separated by only a thin piece of metal that allows the heat to pass, is used to transfer the energy into the load.
Solar hot water heaters can provide households with up to 80 percent of their hot water and space heating needs while reducing home energy costs. A back-up heating system for water will be necessary during times when solar radiation is not meeting hot water demands. This back-up system can come from an electric tank, gas tank or tankless water heater. Very large solar thermal systems providing hot water can be found in poultry processing plant throughout eastern North Carolina.
The N.C. Clean Energy Technology Center has a rich history of providing solar thermal equipment testing that includes a Solar Rating and Certification Corporation (SRCC) accredited laboratory. We also provide solar thermal energy assessments to citizens, businesses, and government entities in North Carolina.