Solar district heating for German district

Date: 03/07/2014

A new 2000 m² solar thermal plant connected to a district heating net planned for next year in Chemnitz, Germany.

The local energy supplier ‘eins energie in sachsen GmbH & Co.KG’ is already installing the new district heating pipes in the district of Bühl. It is a LowEx-Net with lower temperatures than the already existing district heating net, which delivers heat between 120 and 80 °C. Therefore, heat losses are lower.

The new part of the net will have a feed-in temperature of 80°C and can therefore be supplied firstly from the return pipe of the traditional district heating net, explains spokesman Christian Stelzmann. The solar plant, which will be built in the second phase in 2015 can deliver heat at this temperature.

The current design foresees a flat-plate collector plant of 1700 to 2000 m². The plant should cover 10 % of the yearly heat demand of the district. It is not planned that the heat will be stored from summer to winter so that a relatively small buffer storage of 1000 m³ suffices.

The cylinder tank will have a diameter of 10 m and be 17 m high. A battery of district heating storages and a cold storage for the district cooling net of Chemnitz are situated nearby.

LowEx district heating is considered a compensating measure to fulfill the Renewable Heat Law. Thanks to the high fraction of renewable energies, more advantageous subsidies can be received for building refurbishment according to the German Energy Saving Ordinance.

The district concept Chemnitz-Bühl is supported by the program ‘Cities Energetical Refurbishment’ (‘Energetische Stadtsanierungs’) of the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safedy and from the Free State of Saxony. Participants in the project are the local energy supplier and the technical University of Chemnitz.