12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaThe return medium of the heating grid is heated up andtransferred to the flow (Fig. 2) [2]. The adaption of solarthermal technology for the temperature and pressurelevels of the district heating grid were challenging. Thisproject was realized with standard large scalecollectors (1420 m² collector area) of the Austrianmanufacturer Ökotech and temperature levels in thedistrict heating flow of above 70 °C have to be reacheddependant on the ambient temperature.During first operation years, detailed monitoring wasdone on the plant‘s performance. Dependant onclimate condition, the annual yield of the plant wasbetween 521 MWh/a and 569 MWh/a. Thiscorresponds to a specific yield of 370–404 kWh/a persquare meter collector area. Also the returntemperature of the heating grid is of great importancefor the performance of the solar plant.Fig. 2: Hydraulic scheme of solar feed-in at Stadion Liebenau2. SDH connected to a large scale fossil fuel firedstation – plant AEVG GrazThis is the largest solar thermal plant in Austria and it isinstalled on four different buildings of the localcollection and recycling station (Fig. 3).Situated next to the central heating plant, pressureparameters are favourable for feed-in. Pressure ishigher in return and thus only valves are necessary andno additional pumps for integration into the districtheating grid.Fig. 3: Solar plant AEVG Graz141