Solar thermal energy: What it is and how it works in detail

  • Solar thermal energy uses solar radiation to generate heat through collectors.
  • Its main use is in water heating and heating in homes and industrial facilities.
  • The system includes components such as accumulators, exchangers and circulation pumps.

solar thermal

When we talk about solar energy, we most commonly think directly of photovoltaic solar panels, which are those that generate electricity. However, there is another type of solar energy that is less known but equally important: solar thermal, an efficient and clean option that is mainly used to heat water and generate heat.

Solar thermal energy plays a fundamental role in both residential and industrial sectors, allowing for greater energy efficiency and a reduction in the use of fossil fuels. In this article, we explain All about this type of energy: its operation, characteristics, components and advantages.

What is solar thermal energy?

What is solar thermal energy

Solar thermal energy is a renewable energy which uses the sun's radiation to produce heat. Unlike photovoltaic solar energy, which converts sunlight into electricity, solar thermal energy heats a fluid by capturing solar radiation. This fluid can heat water, generate heating or even cooling in certain systems.

This type of energy is especially useful in areas with high solar radiation, where it can be used for domestic use and in industrial applications. For example, it is estimated that more than 20% of energy consumption In hotels, hospitals and homes it is related to the use of hot water, which demonstrates its importance.

Components of a thermal installation

Components of solar thermal energy

For solar thermal energy to work properly, it is necessary to have an installation designed to capture, store and distribute heat. Below we highlight the main components of a solar thermal energy installation.

Catcher

The collector or thermal solar panel is responsible for absorb solar radiation and transfer the heat to the fluid circulating inside it. There are several types of collectors depending on their efficiency and technology:

  • Flat collectors: They are the most common and are used for hot water and heating applications in homes.
  • Vacuum tube collectors: They are more efficient, especially in cold areas, thanks to their improved insulation.

Hydraulic circuit

The hydraulic circuit is made up of pipes that transport the hot fluid from the collector to the accumulator, and back to the panel once it has cooled. It works as a closed circuit, ensuring that there is no heat loss.

Heat exchanger

This device allows heat to be transferred from the heat-carrying fluid to the water used in the home or facility. The exchangers can be internal (coils) or external, such as plate exchangers.

Accumulator

Since the amount of solar energy varies throughout the day, a accumulator to store hot water until it is needed. This tank is designed to minimise heat loss and keep water hot for several hours.

Circulation pumps

To ensure that the fluid circulates correctly through the system, they are used circulation pumpsThese overcome the circuit resistances and allow the constant flow of the heat transfer fluid.

Auxiliary power

On days with little solar radiation, solar thermal installations usually have an auxiliary energy system, such as a boiler, which can generate heat in situations where solar radiation is not sufficient.

Items Needed for Safety

Safety elements of solar thermal energy

Solar thermal energy installations must have a series of safety elements to avoid problems related to overheating or system pressure.

Expansion vessels

The volume of the fluid increases when heated, so it is necessary to have a expansion vessel to absorb this increase and prevent damage to the pipes. Expansion vessels can be open or closed, the latter being the most common in modern installations.

Safety valves

Safety valves are responsible for controlling the system pressure and release fluid if it exceeds the established safety limits.

Glycol

The fluid used in most solar thermal energy installations is a mixture of water and glycolThis additive allows the fluid to withstand sub-zero temperatures without freezing, which is essential in cold climates.

Heat sinks

If the fluid heats up excessively, the heat sinks They are responsible for releasing part of the temperature, preventing the installation from reaching dangerous heat levels.

Traps

The drainers allow remove air which accumulates inside the system, guaranteeing optimal functioning of the hydraulic circuit.

Automatic brine control

The most advanced solar thermal energy systems have a automatic control which monitors the different elements of the system, such as the temperatures of the collector, the accumulator or the circulation pumps. In addition, it can activate auxiliary or dissipation energy systems as required.

Thanks to solar thermal energy, we can generate hot water and heating in a more sustainable way. This technology continues to advance, allowing us to increasingly reduce our dependence on fossil fuels and minimize environmental impact.


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