Solar Thermal Panels

Solar Thermal Panels

Picture of a terrace with thermal solar panels

I advise everyone to evaluate for their own apartment (even if they live in an apartment building) if there is the possibility of installing thermal solar panels. However, it is appropriate to do an energy redevelopment intervention because this is the right time to do it.

In fact, the state has implemented a maneuver imposed by the European community to facilitate all those who intend to carry out works that reduce the emission of polluting gases. Example:

  • the installation of forms of clean energy;
  • replacement of fixtures;
  • replacement of traditional boilers with condensing ones;
  • insulation of the external walls and the floor (as thermal insulation I recommend extruded polyurethane foam which has the lowest transmittance values);

Let’s talk now about thermal solar panels; I will try to best illustrate these new technological products.

Table of contents

  • What are solar panels?
  • What is a solar collector?
  • The advantages of thermal solar panels
  • Government incentives
  • How do solar thermal panels work?
  • How to size them?
  • If the sun is not there?
  • What if the sun and the heat is too strong?

What are solar panels?

As we all know, solar panels use solar energy to transform it into useful energy or heat for human activities. Solar panels are divided into two different categories of products depending on their use, we can distinguish them in:

  • Photovoltaic Solar Panels, aimed at the production of electricity;
  • Thermal Solar Panels, aimed at heating domestic water.

We will focus on thermal solar panels to better understand what advantages they can bring to those who decide to install them on the roof of their home.

What is a solar collector?

The solar thermal panel (solar collector) is a device suitable for the conversion of solar radiation into thermal energy and its transfer, for example to an accumulator (kettle) for later use. A solar thermal system normally consists of a panel that receives solar energy, an exchanger where the fluid used to transfer it to the tank used to store the accumulated thermal energy circulates. The system can have two types of natural or forced circulation.

The advantages of thermal solar panels

First of all, the Solar Thermal Panels with Vacuum Tubes with Superconducting heat allow you to heat sanitary water for daily use without using gas or electricity. The thermal solar panels are therefore a substitute for the electric water heater and the gas boiler to obtain hot water, saving up to 90% of electricity. In Euros (for a family of 4) this translates into savings for Electricity of approximately € 300 / A and almost € 200 / A of Gas. Total about € 500 per year, in excess of this the cost of the tube and vacuum collector is amortized in 2 years, not to mention that part of the cost is tax-deductible.

Government incentives

The finance company introduced the incentive consisting in the tax deduction of 65% in the tax return phase for the installation of solar panels for the production of hot water. The incentive requires certification of the collector only according to the UNI EN 12975 standard or of the Collector – Boiler system according to UNI EN 12976, only if the storage unit cannot be separated from the collector; both are not needed.

How do solar thermal panels work?

The solar thermal panel works according to a very simple principle: capturing the energy that reaches the Earth from the Sun and using it to produce hot water at a temperature that can reach up to 80-100 ° C.

The Thermal Solar Panels are composed of the following parts:

  • Real thermal solar panel, similar to a radiator, which allows the heat absorbed by the sun to be transferred to the water in the tank and thus to produce hot water; directly or indirectly;
  • Hot water storage tank and possibly a pump for forced circulation of the water;
  • hydraulic and electrical connections;

How to size them?

To calculate the dimensions of the solar thermal panel to be installed, the square meters must not be taken into account. of the house, but of the number of family members: it is estimated, in fact, that on average the consumption of hot water is equal to 30-50 liters per day per person. Consider that from 3-5 minutes to take a shower about 50 liters of the waterfall.

Other determining factors are:

  1. the water temperature;
  2. pressure;
  3. geographical area;
  4. daily solar radiation.

As an indicative value, we can consider a water production at a temperature of 40 ° C, equal to 80-130 liters per day, for each square meter of panel installed. To heat the water contained in the tank (about 50-80 liters per square meter of solar collectors installed), it takes about half a day of sunshine in the summer and one day in the winter. The water temperature that can be reached from the panels on days of full sun is around 30-50 ° C in winter and around 70-100 ° C in summer.

If the sun is not there?

Thermal solar panels are capable of producing thermal energy even if there is no sun. The radiation incident on a panel is also given by the radiation present in the entire celestial vault. Obviously, if it’s sunny, the panels work better.
In order to have hot water always and regardless of the climate, it is however essential to resort to solutions integrating solar radiation.

This can be done in two ways:

  1. In the house, there is already an electronically controlled instantaneous gas boiler for the production of domestic hot water. It is possible to connect the solar system to the existing heating system. In this case, the solar system integrates the traditional one, with a considerable saving of energy and money!
  2. If it is not possible to connect to the gas boiler, the electrical resistance of at least 1.5 kW with a thermostat set at about 40 ° C must be inserted in the tank. The compact solar panels on the market are equipped with a hole for the integrative electrical resistance positioned inside the tank.

What if the sun and the heat are too strong?

All solar thermal panels must have a safety valve; it generally performs 2 functions: it opens when the temperature exceeds 99 °, it opens when the pressure exceeds 6 bar. In the summer there are no precautions to be taken. If you really want to limit the water temperature as much as possible, you can remove 1 or 2 side pipes, or if you want you can also cover them by partial zing them. There are also electric solar shutters if necessary and due to excess of zeal.

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