Thermal solar panels: type, installation and incentives

Solar thermal panels can contribute to energy efficiency and respect for the environment. Solar energy is clean, renewable and available, although its intensity varies according to the periods of the year and the latitude.

If you want to make your home more and more “smart” by equipping it with solar panels and don’t know where to start, here is a simple choice guide.

To begin with, we need to distinguish between thermal solar panels and photovoltaic panels: in a nutshell, the latter is used to convert solar energy into electricity through photovoltaic cells. I will return to this topic soon. In this image you can see the difference between the two types of panels:

Solar thermal panels

The solar thermal panels, technically called solar collectors, are used for the production of domestic hot water. There are different types of solar collectors on the market, but the most used are:

  1. Flat plate panels: supply hot water and feed the environmental heating with low-temperature systems (radiant panels, floor heating). They are relatively cheap and are the most widespread in Italy.
  1. Vacuum tube panels: they have higher efficiency, even with the sun light shielded from the clouds or weak, as in the winter months, thanks to a heat dispersion reduced to the minimum and to the greater efficiency of the absorbing material of the sunlight used. (see cover photo). The system can be integrated with heating systems operating at high temperatures.

How the system works

The operation of the plant is relatively simple: inside the pipes flows a heat transfer fluid that is heated by solar radiation and which, through a circuit, reaches a tank, in which it transfers the accumulated heat to cold water. The water thus heated is then introduced into the domestic water network. However, the solar heating system must be combined with an auxiliary heating system.

We must then distinguish between two circulation systems:

  • Natural circulation: the passage of the heat transfer fluid from the panel to the tank occurs without the use of electric pumps. The heated fluid, being lighter, rises upwards, according to the principles of convection: it is collected in the tank positioned at the top of the panel itself. This system is not suitable for areas subject to intense and prolonged frosts.
  • Forced circulation: the tank is separated from the panel and positioned inside the house. The circulation of the fluid is activated by a circulation pump, regulated by a control unit.


The solar panels can be installed on the roof, on the terrace or in the garden: the important thing is to position them in the right inclination, with the right orientation, and in a non-shaded point, to have the greatest possible radiation.

While as far as orientation is concerned, the choice is simple, that is to the south with scales up to 45 ° towards the east or west, for the inclination the choice is more complex, as it depends on many factors. For this reason it is advisable to rely on a trustworthy and expert company that can advise you based on the geographical and environmental position of your home: in addition, the technicians will design a customized system suited to your consumption needs.

Good thermal insulation

A good thermal insulation of the house, of the pipes of the system and of the tank contributes to increasing the efficiency of the system, thanks to the maintenance of the high water temperature even when, due to lack of sunlight, the collectors work at the low regime.


Until 31 December 2018, incentives can be used, thanks to the 2.0 GSE Thermal Account, a fund created to support energy efficiency improvement measures. For thermal solar panels, both for new systems and for the replacement of old ones, the bonus can be requested within 60 days from the end of the works, in order to obtain a refund of up to 65% of the expense incurred. On the GSE website, you will find all the information and forms.

Alternatively, you can opt for the Eco bonus, or for the deduction from the personal income tax of up to 65% of the costs incurred, spread over 10 years.

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