Brief
Graz, with its 302,749 inhabitants, hosts a solar district heating plant representing the world’s largest field test for solar thermal collectors with commercial district heating feed-in. It was initiated in 2007 on the roofs of the municipal recycling centre and enlarged when additional areas near the heating plant became available, leading to the establishment of an 8,213m² comprehensive solar collector field for district heating feed-in, testing, and comparison. It plays a pivotal role in the city and utility’s joint efforts to enhance the environmental sustainability of the district heating supply.
Technology
The solar field in Graz features solar thermal collectors from seven different manufacturers, employing various technologies, which underwent rigorous testing and evaluation through research and development projects. Originally, the district heating supply was primarily sourced from combined heat and power (CPH) during winter and gas heating plants during summer. Thanks to the employment of solar heat, renewable energy for domestic water heating is supplied to around 8,000 citizens of Graz around 740 tonnes of carbon are now saved every year. Future plans include a substantial increase in the solar thermal share within Graz’s district heating network.
Financial Structure
Owned by the solar energy service company solar.nahwärme, the project sells heat to Energie Steiermark, which operates a central district heating plant supplying heat to Graz and surrounding villages. It received financial support from the Austrian Climate and Energy Fund.