Heat from the sun for everyone
The use of solar heat in buildings is the most common and widespread employment of solar thermal systems, not only in Europe but also worldwide. This use can be segmented in terms of system size, ranging from smaller applications for single family houses and medium size for multi-family houses to larger applications for tertiary buildings, such as social amenities and commercial buildings.
These larger applications employ mainly forced circulation systems, where a pump is used to circulate water between the collector on the rooftop and the thermal storage inside the building. These systems are suitable for different social amenities, wherever there is a substantial use of domestic hot water. These can include schools, hospitals, swimming pools and sport facilities, dormitories, retirement homes, etc. Similar applications exist in commercial buildings, such as hotels, camp sites, shopping centres, restaurants, car washes, etc.
Description of use
Half of the energy consumed in Europe relates to heating and cooling. Over one third of the EU’s energy-related greenhouse gas emissions come from buildings as the high heating demand is still widely met by fossil fuels. It is crucial to replace this with clean energy technologies, such as solar thermal.
The three main factors to consider regarding the adoption of a solar thermal system in tertiary buildings are the hot water demand in terms of quantity, i.e. when it is needed, the amount, and the desired temperature (to assess the energy required to warm it up from the inlet to the outlet temperature). The size of these systems can vary hugely, from relatively small systems of 10 m² (7 kWth) to systems of 500m² (350 kWth), or even larger. Their operating principle is simple and effective: The solar collector harnesses energy from the sun, which heats a fluid used that is stored in a thermal energy storage unit, ready to be used for space and water heating.
In higher latitudes, where the radiation in winter is significantly lower than in summer, such systems can cover between 60 and 80% of the annual domestic hot water demand. This means that a supplementary or backup heater is required. In low latitudes, solar thermal can cover 100% of the domestic hot water demand a backup heater is required only for exceptional conditions.
Benefits of Solar Thermal
Systems!
The benefits of solar thermal systems, cover environmental, political and economic aspects.
Environmental benefits relate to the capacity to reduce harmful emissions, impacting both our environment and our health. The reduction of CO2 emissions depends on the quantity of fossil fuels replaced directly or indirectly by the solar thermal system, for instance gas or carbon-based electricity used for water heating. Depending on the location, a 2.8kWth (4 m2) system could generate the equivalent of 2.2MWhth/year, a saving of around 350kg of CO2.
Political benefits are associated with the possibility of improving energy security by reducing energy imports while creating local jobs related to the manufacturing, commercialization, installation, and maintenance of solar thermal systems. The solar thermal sector has a strong European manufacturing base, supplying over 90% of the local demand and exporting worldwide. Therefore, opting for solar thermal systems in Europe means choosing solar energy produced by European companies, boosting the European economy and creating green jobs.
Economic benefits are associated with the potential savings in energy costs. Even though solar thermal systems require higher upfront costs, they offer an economic advantage in the longer term. Solar thermal systems ensure price stability for at least 20 years. Analysis of existing systems demonstrates that solar heat is economically competitive with other renewable energy sources and gas. This competitiveness is even more accurate when energy prices fluctuate, as seen during Europe’s recent energy crisis.
There are three main aspects to consider that have a bigger impact on the comparable costs of the energy produced by a solar thermal system. These are the initial costs of the system, the lifetime of the system, and the system’s performance. These factors depend on the location (affecting climate, insulations, taxes, cost of living, etc.) and quality of the system (affecting performance, lifetime, and cost).
This can vary significantly from country to country, thus leading to different average investment costs for solar thermal systems.
For tertiary buildings, pumped indirect systems are the most commonly used. For these, investment costs can go from 765 to 1710 EUR/kWth in central Europe, while in northern Europe they can go up to between 1440 to 2160 EUR/ kWth. In terms of energy costs, the former can range from 16.7 to 26.6 EUR cents/kWhth while the later may range between 9.5 to 23.9 EUR cents/kWhth.
Explore Solar Heat for Tertiary Buildings
Case Studies
Technical information
The operating principle is rather simple. The sun heats a fluid in a solar collector, which is then used to store domestic hot water in a hot water store, ready to be used. Larger systems are usually forced circulation systems, consisting of solar thermal collectors, pipes, hot water store, pumps, controller, heat exchanger, valves and backup heater. The solar irradiation is captured by an absorber and converted into heat. To increase efficiency, the absorber is often selectively coated, which means that the absorption of the irradiation is maximised, but the emission of heat is minimized. The absorber heats a fluid circulating in contact with it. The heat carried in this fluid is then transferred to domestic hot water by a heat exchanger. The domestic hot water is pumped into a hot water storage tank, ready for use. Additional water heating systems, such as heat pumps, usually also feed into the hot water store.
Temperature: Between 40 to 60 degrees Celsius
This is the usual temperature range required for the most common uses, even if the user
lowers the temperature by mixing with cold water.
Control: Simple control and simple metering. Advanced control and monitoring are possible and recommended.
These systems require simple metering and control. Although it is possible, and even desirable, for larger and/or commercial systems to have advanced metering and control, with remote monitoring.
Operation & Maintenance: Generally very low, higher in colder climates. The operating and maintenance requirements are rather simple, requiring usually one routine visit per year.
