Solar Thermal System: How it Works

The Solar Thermal System is a valid solution for optimizing the energy resources of your home while reducing your bill costs. Thanks to this type of system it is possible not only to produce domestic hot water but also to (partially) heat your home. Furthermore, installing a solar thermal system helps to increase the value of your home, without impacting the surrounding environment.

Solar Thermal System Operation

The Solar Thermal System is a system that, by exploiting solar rays, transforms solar energy into thermal energy without producing harmful emissions; to have a concrete idea of ​​how it works, just think that it allows not only to heat homes but also to guarantee them domestic hot water.

The components that make up the solar thermal system are a solar collector, a storage tank, an integration generator (for example a heat pump or a condensing boiler), and a control unit: each of these is connected to the others to guarantee the correct functioning of the entire system.

At the basis of every heating system, there is the same principle: collecting solar energy to transform it into thermal energy. Through the panel, sunlight reaches the absorber, which, as it heats up, transfers the heat to the heat transfer fluid (usually water mixed with antifreeze). The heat transfer fluid in turn will transfer the water to the users which can be hot water for sanitary use and water from the heating system.

Heating domestic water is the most frequently used because the temperatures used make the solar system more efficient and furthermore domestic water is used throughout the year; Solar integration into the heating system is only convenient in the presence of low-temperature heating systems, For Example, radiant panels.

Difference Between Photovoltaic and Solar Thermal

When we talk about photovoltaics and solar thermal systems we think that the two concepts overlap, but this is not the case: in fact, the only thing in common between the two technologies is that they both exploit solar rays to produce energy, as photovoltaics convert the sun’s rays into electric current while the solar thermal system accumulates the heat. In addition to their purposes, the two systems differ in various characteristics:

  • The material that mainly constitutes photovoltaic systems is silicon combined with various chemical elements, glass, and various structural components; solar thermal systems are instead made of metal (aluminum, copper, steel) and glass
  • Even in terms of efficiency, the differences between the two systems are marked: photovoltaic has an average efficiency between 17% and 25%, while solar thermal enjoys a higher efficiency that can reach up to 80%.
  • As regards tax breaks, photovoltaic systems can reach up to 50% deduction, while for solar thermal systems, it can reach up to 65%.

Types of Solar Thermal

There are two different types of solar thermal. The first classification is based on the temperature that the panel is able to make the water reach: they are called collectors at low temperatures up to 120 degrees, medium temperatures between 120 and 500 degrees, and finally high temperatures when it exceeds 500 degrees. For residential applications, the former are mainly used. Other criteria used for the classification of solar are the type of mechanism exploited by the components used:

Types of Solar Thermal

Direct Storage Solar Thermal System: 

It is composed of a tank and a surface for heat absorption which must be positioned in a place exposed to abundant sunlight. This is an economical solution, suitable for users with hot or even lukewarm water consumption concentrated in the summer period, such as bathing establishments

Natural Circulation Solar Thermal System: 

It consists of flat solar panels above which a double-layer storage tank is positioned. The circulation of the heat transfer fluid occurs naturally: in this case, the water heats up inside the collectors, where it expands, becoming lighter and rising, taking the place of the colder fluid. This creates a natural circulation of the fluid which heats the domestic water contained in the accumulation inside the tank. The domestic water will then be distributed within the domestic systems thanks to the network pressure. It is a simple and economical system, but provides for a high dispersion of the accumulated heat

Forced Circulation Solar Thermal System:

In this case, a pump regulated by an electronic control unit pushes the heat transfer fluid inside the collectors, where it heats up, and then toward the components of the heat accumulation and transfer system to the domestic water, located inside the building

In the Description of Solar Thermal Systems, reference has always been made to a storage tank as the use of thermal energy, for example for showers, can occur at any time regardless of the presence of solar radiation; the tank therefore allows you to accumulate energy to use it when necessary.

Solar Thermal Advantages

Installing a solar thermal panel has numerous advantages for a family: in fact, its use can reasonably cover up to 70% of the domestic hot water requirement with a significant saving on the electricity or gas bill.

The installation of a solar panel, chosen based on the possibilities offered by the type of building, allows you to get closer to energy independence at limited costs. Furthermore, owning a solar system increases the value of your home. If the minimum maintenance required is guaranteed every few years, a well-built system will on average last 20 years.

No less important, the use of solar thermal significantly reduces emissions of carbon dioxide, sulfur oxides, and other polluting substances, improving the conditions of our planet, without giving up the comfort of hot water.

Incentives and Tax Deductions for Solar Thermal Systems

There are two main incentives for those who install a solar thermal system in Italy, as well as various possible local benefits: tax deduction (so-called Ecobonus) and Thermal Account. With the Ecobonus it is possible to obtain a 65% deduction for a single home on the expense incurred for the solar system, as well as for other types of interventions. For condominiums the deductions are higher: we are talking about 75% for interventions that improve the energy performance of the building. The Thermal Account instead provides a capital incentive over two or five years for various energy efficiency interventions which, in the case of solar thermal, can cover a variable share (between 40 and 60%) of the expenditure.

Bosch is a company expert in the production of solar thermal systems: green and efficient solutions that contribute to the reduction of energy consumption and carbon dioxide emissions.

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