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Thermal solar energy


The use of photovoltaic solar energy at the domestic level is something very well known today. However, solar thermal energy is somewhat more unknown. Thanks to this type of installation, the heat of the Sun can be used to transport it to a heat transport medium, to produce heating and sanitary hot water.

Despite this ignorance, the growth of this type of facilities at a domestic level has had a very significant growth. Although self-consumption cannot be achieved, they support the production of heating and sanitary hot water, both for homes and companies.

What is it and what types of solar thermal energy are there?

As we have already mentioned in the introduction, solar thermal energy can be used for domestic hot water and heating in a building.

However, there are other applications, such as the production of electricity or even cold, although due to the complexity of the facilities to achieve this, it is not yet developed at the domestic level.

Sanitary Hot Water

The so-called thermosyphon is the simplest system, which uses solar heat to produce domestic hot water. Many of us are familiar with these computers. You must have seen them on the roofs or terraces of many single-family houses, hotels, etc. And they are easy to identify because they have one or two solar panels and are positioned horizontally over these tanks.

The name of the thermosyphon is given by its operation. Because the movement of water in solar thermal energy equipment is carried out by the temperature difference between the heat transfer fluid that flows through the plate and the heat storage coil. Only when the tap is open, the drinking water enters the cold water from the water meter and leaves the water tank. And it is driven by cold water and does not require a circulating water pump.


To support the heating, we need a forced circulation system. That is, a pump is required to force the water or glycol to move in the circuit. In addition, they are characterized by having many solar panels and accumulators inside the house.


For the generation of electricity with solar thermal energy, a large installation is required. These facilities are called solar thermal power plants. Solar thermoelectric power works similar to a thermal power plant, but uses solar energy instead of coal or natural gas. The sun's rays are installed in the receiver of the solar thermal energy installation through a mirror and the temperature of the receiver reaches 1,000ºC. This heat is used to heat the fluid and produce steam, which drives a turbine and produces electricity. Although the first power plants could only operate on a few hours of solar radiation, today it is still possible to store heat at night to generate electricity.


The absorption cooling system of solar thermal energy equipment is a means of generating cold air, which takes advantage of the fact that matter absorbs heat when it changes from liquid to gas. This cycle is physically based on the ability of certain substances (such as lithium bromide) to absorb another substance (such as water vapor).

The basic physical process consists of at least two chemical components, one serving as a refrigerant and the other as an absorbent. Absorption machines can be classified based on the pairs of substances that act as coolant / absorbent.

What are the components of solar thermal energy?

When we want to install solar equipment in our homes, we must know that it is not only composed of well-known solar panels. To capture the energy from the sun's rays, store it and use it as thermal energy, it is necessary to install other components, which are part of the solar thermal energy system.

Solar collectors

Solar collectors are called solar panels or solar panels. It is well known that they are located in the visible part of the solar installation because they are located on the roof of a single-family home or building. However, at first glance, if we do not know the exact composition of solar energy, we can mistake it for photovoltaic technology.

These components of the solar thermal system are responsible for collecting solar radiation. In these plates, the heating fluid is heated and then circulates in the circuit. There are also several types of collectors: low temperature, medium temperature or high temperature.

Closed circuit

The closed loop is the second most important part of the system. Heat transfer fluid circulates in it (generally glycol, which consists of a mixture of antifreeze and water), and this fluid comes from the collector.

You must distinguish between exit loops and return loops. The closed loop is made up of pipes that connect the remaining components of the loop. Among these circuits, one acts as the main circuit and the other acts as the secondary circuit. The first layer is the one that connects to the collector, goes to the exchanger and returns, and the second layer is the one that leaves the exchanger and goes to the solar collector, distributing the water throughout the property.

Heat exchanger

The third element of this type of installation is the heat exchanger. This element transfers heat from the ethylene glycol in the primary circuit to the water in the secondary circuit, that is, to the water to be consumed.

As the name suggests, its function in solar installations is to exchange heat. In some cases, the exchanger is not a single element, but is integrated into the accumulator, as can be seen in the operating diagram.


Sometimes the energy is not consumed immediately, so the device can store hot water for later use. Your job is to accumulate water without cooling quickly and then provide water when needed. In other words, they are isolated storage tanks with a specific capacity to avoid energy losses in solar installations.


As the name suggests, in a solar installation, a pump pumps fluid to flow through the entire circuit. In other words, they are the heart, and their movement causes the water or glycol to move in the primary and secondary circuits. On the other hand, it avoids the loss of load in the circuit. This is another important part of solar energy.

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