Solar thermal technology uses sunlight striking a capture surface to heat up a fluid running in a circuit, which can then be used for various applications.
The system features a series of modules exposed to the sun, a connecting circuit, a storage tank (for times when the sun is not strong enough), all connected to the traditional gas or electric boiler. The system must be integrated with traditional systems to prevent the user being left without service during periods like the winter, when there is not sufficient sunshine.
Solar thermal technology, like all other renewables, has two types of environmental benefit:
- Zero greenhouse gas emissions.
- Reduced extraction demand on conventional and fossil fuels.
Solar thermal technology preheats the user fluid (water or air) thus limiting the temperature differential (user temperature – input temperature) that a conventional energy source must overcome to provide the desired user temperature. In conditions when the system balances the energy draw against with the available sunlight, it can provide total preheating – in other words, completely replace the fossil fuel energy required to heat the water/air.
Solar energy replaces traditional energy sources like petrol, gas and coal and reduces emissions of CO2 (greenhouse gas) and other exhaust gases. Compared with an electric boiler, a 4 m² solar thermal installation can save up to 1,500 kg of CO2 a year.
Under current legislation, solar systems are considered works of public utility and extensions of the water mains system, and hence generally fall under the authorisations required for such installation.
If the Municipality does not reply to an application within 30 days of receiving it, work may begin.
If the building is in the town centre, is a heritage building, or under some specific restriction, you must follow the procedures provided by local authorities. Usually, this means you have to submit an application, including design and photographs, to the local heritage authorities. Note however that the actual system is completely concealed by the roof panels themselves. Since the system is not visible, it is particularly easy to get authorisation even for buildings with special restrictions.
Forced circulation employs a pump to drive the vector fluid through the circuit and deliver heat to the hot water tank, when required to do so by the electronic controller and its temperature sensors. If there is no sunlight (at night or in overcast conditions) or the maximum tank temperature has not been reached, the pump stops so that the fluid does not lose heat outside or inside the system.
Gli impianti solari termici con scambio ad acqua sono di vari tipi e la casistica si amplia molto a seconda delle condizioni di installazione e alle esigenze del singolo utente. Esistono impianti per l'acqua calda sanitaria, per il riscaldamento degli ambienti, ibridi fra i due, impianti per il riscaldamento di grandi quantitativi d'acqua (piscine o accumuli stagionali di calore), o per la produzione di vapore a pressione (anche se sono utilizzati in contesti industriali).
For personal hygiene, or for heating rooms with low temperature heating systems, for the swimming pool, even for washing machines and dishwashers. Heating systems which are used every day consume less energy since the starting temperature is not as low as the water mains temperature.
Solar thermal technology, like all energy saving solutions, has a significant scaling effect. The larger the volumes, the better the performance. Industrial processes which require large volumes of hot water are ideal for this technology, so long as the conditions for heat exchange actually exist.
During the summer, the hot water requirement is perfectly balanced with the amount of available sunlight. Large domestic installations designed to heat the home or provide hot water during the winter can use the excess produced during the summer to heat swimming pools, thus extending its period of use beyond the normal season.
Obviously yes, and for both air and water solar thermal systems. In the case of water systems, heating supply is most suited to low temperature radiators, wall or floor mounted. Theoretically, one could also integrate them with fan heaters, although this would not be the most suitable (or mostly cost-effective) approach. As for air systems, this is their ideal application. Air panels offer hot air at the ideal temperature for heating the rooms.
Theoretically yes, you only need a good roof area or structure sufficiently large to support the square metres of capture modules required to supply the demand for heat in each case. The other factors are the orientation of the supporting roof or structure, angle and location. As for the storage system, it is usually installed in the boiler room, or under the roof or in the cellar, in forced circulation solutions. In apartment blocks, one could imagine a centralised solution with individual meters thus enabling direct control of tenant draw, which would also provide better performance of the solar system itself.
Certainly, so long as the proper functionality is available for the solution to work.
The cost of fabrication and installation has a cost which is amortised by calculating the cost of the energy one would otherwise have purchased (gas or other fossil fuel). It takes about 5-10 years to recoup the initial investment in this way, including maintenance costs. After the initial cost has been amortised, you can consider yourself to be “earning” money.
In the case of water systems, you must take the following factors into account:
- You must know the approximate position and area of the surface to be used for the capture modules
- You must know the number of people using the system, so as to be able to size it accordingly
- You must have space for the storage tank
The service life of the entire system depends on the plumbing system, so we estimate it to be around 30 years. But the capture module itself has a practically unlimited life, due to:
- copper’s ability to protect itself against the weather and atmospheric agents
- the system is constructed of just one material, copper, which avoids material incompatibility and thermal dilation issues
- copper sheeting has excellent tensile strength, and is thus not likely to collapse or fail under the weight of snow, hail, etc..
The capture module itself does not, but the roof must be maintained like any other roof. The system itself requires two types of inspection:
- Condition of the storage tanks
- H of the vector fluid.
If you keep these two parameters under control, a well-sized system will lost for many years without problems.
The solar module is not covered, i.e. it is not fitted with glass or polycarbonate panels to create a greenhouse effect which can cause problems of stagnation when the fluid gets close to boiling point. There is thus no need to bleed or drain the coil when the system is not in use.
The system is designed with modular elements which integrate perfectly with each other, and are easy to remove/replace. The system can thus be expanded by simply brazing the new elements onto the existing plumbing circuit.
In the case of a solar thermal installation, the electrical components (pump, controller) require electric current. The costs are no more than 15 €/year. Regular maintenance ensures that the system lasts for many years, and costs around 100 €. In contrast to heating systems, the system need only be serviced once every two or three years.