Solar Thermal

Solar thermal technologies use the sun’s power to heat air or water. The two types of solar thermal technology are passive and active.

In passive solar technology, no mechanisms are used except for the sun’s rays. This is useful to heat air for homes or cooking. For our homes, windows on the south side will let the sun’s light get inside. Any dark object that can 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 it for when the house gets cold, at which point it will give off heat.

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 placed on roofs where they can get the most sun and absorb a lot of heat. The air system could help to heat a house, while the liquid system would produce hot water or be used in radiant floor heating. The liquid systems use a food-safe antifreeze or a drainback design because water could possibly freeze, expand, and break the pipes or collector. A heat exchanger, where the hot heat transfer fluid are separated by only a thin piece of metal that allows the heat to pass, is used to transfer the energy in to the load.

Duke University Bryan Center solar thermal array

Duke University Bryan Center solar thermal array (photo provided by Holocene Energy)

Solar hot water heaters can provide households with a large proportion of their hot water needs (50% to 80%+), as well as space heating needs, while reducing home energy costs. A back-up heating system for water will be necessary during times when solar radiation is insufficient to meet hot water demands.  This back-up can come from an electric or gas tank or tankless water heater.


Duke University Bryan Center solar thermal tank

Duke University Bryan Center solar thermal tank (photo prvided by Holocene Energy)


The N.C. Clean Energy Technology Center has a solar thermal testing laboratory that is working toward becoming an SRCC accredited laboratory. We also provide solar thermal energy assessments to citizens, businesses, and government entities in North Carolina.


Learn More

Solar Testing

Renewable Energy Assessments

NCSU Solar House

American Solar Energy Society

Solar Energy Industries Association