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The thermal solar system Hirtenwiesen II in Crailsheim has a collector surface area of around 7,400 square metres.
© Anna Durst, BINE Informationsdienst
Inauguration of thermal solar system
29.05.2012

The thermal solar system Hirtenwiese II includes an around 7,400 m² collector surface area (1) as well as one solar station (2), one hot water storage tank (3), one solar centre (4) and two buffer storage tanks (5).
© Stadtwerke Crailsheim

Storing the sun for learning and living

Germany´s largest solar thermal system, "Hirtenwiesen II", was inaugurated in Crailsheim in Baden-Württemberg, Germany. In addition to 260 accommodation units, the solar local heating supply system also supplies a school and a sports hall. The collector surface area is around 7,400 m² and includes one borehole heat exchanger heat storage tank and two buffer storage tanks. The German Federal Ministry for the Environment was one of the sponsors of the showcase project.

The development area “Hirtenwiesen II” was built on the former 115 ha barrack grounds in Crailsheim. One grammar school and its sports hall as well as around 260 single family homes and terraced houses are now being supplied via a local heating network for heating and domestic hot water supply. “The main challenge is to reduce consumption, with ‘efficiency’ being the keyword, “ emphasised Dr Urban Rid, Director General, German Federal Ministry for the Environment, Environmental Protection and Nuclear Safety (BMU). “The project in Crailsheim is about efficient construction and heating, which is why it is innovative,” he added.

The solar heat supply consists of a 7,410 m² solar collector surface, one 100 cubic metre or one 480 cubic metre buffer storage tank and one 39,000 cubic metre hot water borehole heat exchanger heat storage, a long-term storage system that stores hot water. The pressurised hot-water tanks (without heat exchanger) are directly integrated into the heat generation. The ground absorbs the heat through borehole heat exchangers and stores it from summer to winter. In the dam centre the solar heat as heating and hot water is fed to the heating network. The solar centre is underneath the sports hall. It regulates heat supply in the local heating network.

Domestic hot water heating in the residential buildings follows the circulatory principle. The supply temperature of the local heating network should be 65°C, and the average return temperature, 35°C. The expected total heating requirement of the local heating network is 4,100 MWh/a (incl. distribution losses), 50 per cent of which is to be covered by solar energy. Even in 2011 direct use of solar energy achieved a solar share of fraction of around 36 per cent. In the future, the running and monitoring of the heat pump and the collectors on the sound-proofing wall are to be tested.

Germany’s largest solar thermal system

The system concept was developed at the Institute for Thermodynamics and Thermal Engineering (ITW) at the University of Stuttgart in collaboration with the Steinbeis Research Institute for Solar and Sustainable Thermal Energy Systems (Solites). It was further specified through a number of simulation calculations. Solites is responsible for monitoring the system until July 2012.

In December 2004 the project in Crailsheim was selected by “Impulskreis Energie” as one of four innovative beacon projects. It is the only one in the area of renewable energies. The project received funding from the Crailsheim municipal utility company, the Baden-Württemberg Ministry of the Environment, Climate Protection and the Energy Sector and the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU).

Other projects

Other showcase projects in the area of solar local heating supply: “Summer sun against the winter cold” (02/2011), “Solar retrofitting of local heating“ (12/2009) and “Local solar heating – New housing estate Speyer” (14/2006).

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Scientific evaluation and monitoring
Universität Stuttgart, ITW

Scientific and technical project support
Solites