This solar district heating plant in Graz represents the world’s largest field test for solar thermal collectors.
Energie Steiermark’s central District Heating plant supplies a significant portion of the City’s District Heating needs, with a peak load of 550 MW and an annual demand of approximately 1200 GWh to the town and surrounding villages. Originally, the district heating supply was primarily sourced from combined heat and power (CHP) during winter and gas heating plants during summer.
In 2007, a 3.5 MW (5000 m²) solar thermal installation was initiated on the roofs of the municipal recycling center. Subsequently, additional areas near the heating plant became available, leading to the establishment of a comprehensive collector field for district heating feed-in, testing, and comparison. This field featured collectors from seven different manufacturers, employing various technologies, which underwent rigorous testing and evaluation through research and development projects.
Owned by the solar energy service company solar.nahwärme, the project sells heat to Energie Steiermark. It plays a pivotal role in the city and utility’s joint efforts to enhance the environmental sustainability of the district heating supply. Future plans include a substantial increase in the solar thermal share within Graz’s district heating network.