District Heating Mürzzuschlag

Solar District Heating for a middle town

In Mürzzuschlag is Austria’s largest ground-mounted solar thermal system

Mürzzuschlag is a town of 8,500 inhabitants in a mountain region between Vienna and Graz. It’s district heating system used to be fired by natural gas and biomass boilers. As both are scarce ressources, the integration of solar thermal was very much appreciated.

The customer Stadtwerke Mürzzuschlag wanted to keep its high share of renewable energies in the district heating grid at low emissions. And the utility didn’t want to invest on its own, so they preferred an ESCo deal.

After a suitable area close to the heating grid was found, SOLID developed a solution with a large collector field and 3 heat storages of 180 m³ in total in 2020. The ESCo company SolarWärme MZ GmbH was founded. This company owns the solar plant and sells the produced solar heat to the utility.

The customer has advantages due to a higher renewable share than before and due to peak load management by the storage. The possibility of extension was already integrated by installation of larger pumps and pipes, and was realised in 2023. Due to the numerous new connections to the Mürzzuschlag district heating system, the plant was expanded to 6850 m² (4800 kW) and 420,000 litres of storage volume. This will further increase natural gas and CO2 savings.

Gefördert von 


Technical Specifications


CO2 Savings
930 t/a

Collector area
6850 m²

420 m³

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