In 1997 Eibiswald district heating installed its first solar district heating plant of 1246 m² collector area. As the district heating network of the village in South Western Styria, Austria, doubled its size in recent years, the collector area was enlarged by another 1200 m² by end of 2012.
The biomass-fired district heating plant of Eibiswald started operation in 1994 and in 1997 the first solar thermal plant went in operation. It was installed on two roofs of biomass storage buildings north and south of the brook Saggau. At start of operation, the solar thermal plant could cover over 90 of the heat demand in summer months. Surplus heat could be used for wood chip drying. In following years, district heating company “Nahwärme Eibiswald” succeeded in finding new customers and the heat demand rose despite renovation of existing buildings. By 2012, the grid had a length of 10.000 meters and an annual heat demand of 7-8 GWh. So it was decided to build a new solar thermal plant in order to cover the increased summer time demand. In addition to the solar thermal plant, two wood chip boilers of 2,3 resepectively 0,7 MW heating power generate heat. With the first solar plant, a buffer of 105 m³ was installed. In 2012, another buffer of 70 m³ was installed in order to increase the heat storage capacity of the entire solar thermal plant.
The new solar plant is built on the south facing roof of a new storage and chipping building, at an inclination angle of 25°. It is also planned to build a photovoltaic system on a small part of the roof which was not covered with collectors. For the new solar plant, an additional pump unit and heat exchanger were installed.
The solar thermal plant was supported by the Austrian “Klimafonds” programme for large scale solar thermal plants. In the framework of this programme, AEE Intec, Gleisdorf, will conduct a measurement scheme on site for one year.
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