A HELIOFLEX® foldable solar roof is being installed at the Vienna wastewater treatment plant in Simmering. Above the “West 2” primary settling tank, an existing infrastructure area will additionally be used to generate solar power – without requiring any additional land.
The pilot project is being implemented for ebswien kläranlage & tierservice Ges.m.b.H., a wholly owned subsidiary of the City of Vienna. Following our first project in Grazerfeld, Vienna will be the second foldable solar roof project to be implemented in Austria.
504 solar modules above the settling tank
The foldable solar roof has an installed capacity of 262.08 kWp. A total of 504 solar modules are distributed across 14 module rows, covering an area of approximately 1,750 m². The system is expected to generate around 260 MWh of solar power per year.
The key feature is its movable design. The solar modules are suspended in foldable roof groups from tensioned support cables and can be fully retracted or extended within approximately 30 seconds. This ensures that the primary settling tank below remains accessible for operational work, maintenance and cleaning.
At the same time, the foldable solar roof protects itself during extreme weather events: in the event of strong winds, hail or heavy snowfall, the system automatically moves into its protective position.
Combining solar power generation with plant operation
Wastewater treatment plants often have large areas available that are simultaneously required for ongoing operations. A conventional, permanently installed roof structure can restrict access to tanks and technical equipment.
HELIOFLEX® therefore combines solar power generation with the operational flexibility required at the site. This allows an infrastructure area that is already in use to additionally generate renewable energy without compromising its original function.
A pilot project with further potential
The foldable solar roof above the West 2 primary settling tank is initially planned as a pilot project. If the technology proves successful in operation, additional tank areas can be assessed for potential use.
The potential is significant: a feasibility study has identified a total area of approximately 46,000 m² at the Vienna wastewater treatment plant as generally suitable for foldable solar roofs.
If the expected yield of the current pilot project is extrapolated to this area, the theoretical potential amounts to approximately 6.8 GWh of solar power per year. This is roughly equivalent to the annual electricity consumption of 2,720 Viennese households.
The Vienna project once again demonstrates the potential of intelligently using existing infrastructure areas for multiple purposes.
back to all News