Status

completed

Short description

The combined use of solar energy for heating and cooling has the potential to upgrade solar thermal energy from a mainly domestic hot water provider to a major building energy supplier. Up to now the necessary sorption chillers were only available in a higher power range (>100 kW). The new small-scale sorption chillers will open the market for small applications, which make up for the major part of the heating and a constantly growing part of the cooling demand in Europe. Thus, accelerating and smoothing the market entry of small scale Solarcombi+ (SC+) systems, the project will contribute considerably to achieving important energy policy goals of the European Union; in particular relating to the share of renewable energies and the security of energy supply in the European Union. Furthermore the project supports the market entry of a technology where a group of European enterprises has a favourable starting point for international leadership. The participation of numerous European producers of small-scale solar-driven sorption chillers as direct partners as well as the declaration of interest of the solar thermal industry shows the importance of the project for a smooth and sustainable market entry of Solarcombi+ systems.

To identify standard system configurations for SC+ plants and most promising applications, several virtual case studies were performed within this project. Based on market analysis, promising system configurations (package solutions) were simulated for typically boundary conditions (i.e. utilization, climate, building type) and economically and ecologically evaluated. Furthermore geographical maps were developed, which allows a simple analysis of locations, which are adequate for SC+ applications. Finally, various dissemination activities were performed to communicate the project and its results.

The market-analysis showed that the European market for air conditioning actually shows an increasing growth rate. It could be identified, that small residential, office and commercial buildings, equipped with a central cooling distribution system, are a promising market for Solarcombi+ systems.

The realised simulation study in TRNSYS based on broad numerical simulations, whereas a broad range of parameters was varied (type of chiller, type of building, location of the building, kind of energy distribution system and kind of heat rejection). Within each defined system a variation of the collector area (from 2 to 5 m²/kW cooling capacity) and each with a various storage volume (from 25 to 75 l/m² collector area) was effected. The analysis of the simulation results showed, that a combination of a collector field with 4 to 5 m²/kW with a storage heat volume of 50 to 75 l/m2 showed the best values according to primary energy savings. Solar fractions up to 80 % and primary energy savings up to 60 % (with natural gas boiler as heat backup) could be achieved. Systems with solar autonomous cooling showed quiet better values.

Based on the simulation results an online tool was developed, wherein several simulation results are deposited (like collector area, storage volume, solar fraction or primary energy savings). With that tool it is possible to compare the influence of the general requirement data on the characteristic values and choose the most advantageous configuration for the current case.

Promising markets could be elaborated and defined as well as visualised in European-maps by comparing the building-energy-demand with the available local solar irradiation across Europe. It could be shown that locations in southern European countries suit better for cooling applications due to the higher solar irradiations there. For locations in northern European countries passive cooling solutions could be a better opportunity.

On the basis of the analysis of the simulation results available package solutions could be defined, which were brought on the market. In these packages pre-defined components for the whole solar cooling application were described according to one specific sorption chiller.

Therewith the planning and installation effort for Solarcombi+ systems could be decreased considerably.

In the framework of this project some dissemination activities for communicating the project and its results were made:

• Establishing and operation of a project website
• Emission of newsletter
• Creation and dissemination of brochures
• Publishing of articles in professional journals
• Design and presentation of poster and leaflets
• Active participation on fairs and conferences
• Organisation of seminars, workshops and presentaions
• Mentoring of public authorities for subsidisation of Solarcombi+ applications
• Recommendations within the Energy Performance of Buildings Directive (EPBD) for Solarcombi+ systems
• Feasibility studies
• Press release in several newspaper

There could be obtained some basic recommendations for the planning of SC+ systems due to the project:

• Big collector areas: 3.5 to 5 m²/kW cooling capacity and a heat storage volume of 50 to 75 l/m² collector area.
• Optimised control strategy: Adapted control strategy of the system according to the location, the application and configuration – especially the control strategy of the heat rejection.
• Cooling energy distribution: Prefer chilled ceiling systems due to their higher cold water temperatures instead of fan coils.
• Solar autonomous cooling: If the SC+ system is big enough, the coverage of the building’s cooling energy demand can be over 90 % and there is no need for a backup.
• No fossil heat back up for thermal cooling.

The project showed that SC+ systems could generally result in primary energy savings if they are dimensioned well and operated proper. Unfortunately, some already existing plants show quiet bad primary energy savings. In the framework of the IEA SHC Task 38 several plants for solar cooling were monitored with the result, that only a few plants showed satisfying results. Nevertheless there could be detected relative big optimisation potentials. Mostly the reasons for malfunction could be found in the conventional system parts and the overall control part but not in the solar thermal cooling part itself.

Thus, there is still a quite huge research requirement for SC+ systems to operate them more efficient and economical so that this technology gets more competitive to conventional appliances.

Project manager

AEE - Institut für Nachhaltige Technologien

Project and cooperation partners

Industrial partners

• SorTech (DE)
• Climatewell (S)
• Fagor/Rotartica (E)
• SOLution (AT)
• SonnenKlima (D)

Research institutions

• EURAC (I)
• Tecsol (F)
• Ikerlan (E)
• CRES (GR)
• Universität Bergamo (I)
• Fraunhofer ISE (DE)
• AEE INTEC (AT)