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In 2020, the capacity of large solar-thermal arrays feeding into Germany’s district heating networks grew by 41%. With more than 31,000 m² (334,000 ft2) of gross collector surface area starting operations, it was the most successful year ever for solar district heating in the country, the Steinbeis Research Institute Solites reports.
A Super-Green Technology on the Rise
By the end of the year, Germany boasted 44 solar district heating plants with a collector surface of 107,000 m² and a total capacity of 75 MW. Three new multi-megawatt systems commissioned in the first half of 2020 contributed the lion’s share of the growth.
New records are coming and going fast and furiously. In February 2021, a new largest-ever 14,800 m² (3.7 acre) plant started delivering CO2-free heat to buildings in Ludwisburg/Kornwestheim in Germany’s Southwest. But that record is about to fall to an even bigger plant currently being built in the northeastern city of Greifswald.
“In the last five years we’ve seen rapid growth in the German solar district heating market – something we’re forecasting will continue into the future”, says Patrick Geiger, a researcher at Solites.
Based on known projects, both under construction and planned, the experts at the Stuttgart-based research institute expect the number of facilities to double by 2025 to 90 and the total collector surface area to triple to over 300,000 m² (74 acres).
Competitive and Space-Efficient
Predictable and low heat production costs are a major driver for the market development of solar district heating. Large plants can deliver heat at about 40 – 70 €/MWh (net) – especially thanks to attractive funding from the federal government – which makes the technology competitive with fossil-based heat production. Increasing CO2 emission prices and EU requirements on decarbonizing district heat networks will likely reinforce this trend in the coming years.
“Systematic communal heat planning is needed if the potential for solar district heating is to be realized“, says Dirk Mangold, director of Solites. “Planning authorities have not paid attention to securing potential sites for solar heating. The growing competition for surface area is one of the biggest challenges facing the energy transition – in the heating sector as well.”
Yet competition for space could be a driver of solar-thermal district heating, which is characterized by its extremely high surface efficiency. With an annual heat yield of about 2 GWh per hectare, solar-thermal is three or four times more space-efficient than photovoltaics and 30 to 50 times more so than the cultivation of energy crops.
A Key to Decarbonizing the Building Sector
“The development of district heating networks based on renewable energy and waste heat is a key to quickly decarbonizing the building sector. Solar heating, large-scale heat pumps and geothermal energy have the greatest potential”, Mangold remarks.
Press release (in German)