What type of solar system component should be used to manage expansion and contraction of fluids?

The correct choice is to use an expansion tank to manage the expansion and contraction of fluids, particularly in systems that involve heating and cooling, such as those found in solar thermal installations.

An expansion tank is specifically designed to absorb the extra volume of fluid that occurs when water or another fluid heats up and expands. In closed-loop systems, the fluid can increase in volume as it gets hotter, and if there is no room for this expanded fluid, it can create excessive pressure that may lead to system damage or inefficiencies. The expansion tank provides a space for the excess fluid to go, maintaining system pressure within safe limits.

These tanks typically contain both water and air. As the fluid expands, it pushes against the diaphragm in the tank, compressing the air, which in turn alleviates pressure in the system. This balance helps maintain operational integrity and prevents potential failure of mechanical components due to pressure fluctuations.

In contrast, while other components listed may play roles in thermal management, such as controlling fluid flow or acting as energy reservoirs, they do not specifically address the need to accommodate volume changes of fluids caused by temperature fluctuations in the same way that an expansion tank does.