At the Birmensdorf wastewater treatment plant (WWTP), the HELIOFLEX solar folding roof has enabled an innovative solution for the sustainable use of existing infrastructure. The system spans approximately 1,900 m² above existing treatment basins, combining reliable wastewater treatment with the local generation of renewable solar energy – without requiring additional land use.
With an installed capacity of 374.4 kWp, HELIOFLEX unlocks the energy potential of previously unused infrastructure surfaces. While the treatment basins remain fully operational underneath the system, photovoltaic modules installed above generate clean solar electricity.
The roof structure integrates seamlessly into the existing facility while meeting high standards in operational safety, maintenance accessibility and long-term durability.
The photovoltaic system generates approximately 370,000 kWh of solar electricity annually. A significant share of this energy can be consumed directly on site, helping to increase the plant’s self-consumption and reduce reliance on external electricity sources.
Energy-intensive infrastructures such as wastewater treatment plants particularly benefit from this combination of local power generation and continuous energy demand.
By producing renewable electricity directly on the WWTP site, the installation saves approximately 35–40 tonnes of CO₂ emissions per year. The project therefore makes a measurable contribution to reducing greenhouse gas emissions and supports municipal and regional climate goals.
The Birmensdorf project demonstrates how technical infrastructure and renewable energy generation can be combined efficiently and intelligently. The consistent dual use of existing surfaces makes the HELIOFLEX solar folding roof especially attractive for wastewater treatment plants and other energy-intensive infrastructures where available roof or open spaces are limited.
With HELIOFLEX, the Birmensdorf WWTP becomes not only a facility for modern wastewater treatment, but also an active contributor to the local energy transition – resource-efficient, space-saving and future-oriented.