With the HELIOFLEX® foldable solar roof at the Frankfurt-Niederrad wastewater treatment plant, dhp Technology has successfully delivered another project that enables the dual use of existing infrastructure. Installed on the premises of Frankfurt's municipal wastewater utility, the system generates solar energy without affecting the facility's primary function.
The foldable solar roof has an installed capacity of 151.36 kWp and is expected to generate approximately 150,000 kWh of solar electricity per year. A total of 352 PV modules are installed across eight movable roof sections. Covering an area of approximately 1,188 m², the system was successfully commissioned in June 2026.
One of the project's key features is its integration into an existing operational facility. Unlike greenfield developments, the implementation required careful consideration of the site's structural and operational constraints. Planning and construction were carried out while maintaining the normal operation of the wastewater treatment plant, requiring close collaboration between the operator, engineers, authorities and installation teams.
The project demonstrates how HELIOFLEX® can be successfully integrated into complex existing infrastructure, opening new opportunities for locations where conventional photovoltaic systems may be difficult to implement.
Like all HELIOFLEX® systems, the Frankfurt-Niederrad installation operates automatically. The solar roof unfolds in the morning and retracts in the evening. In the event of strong winds, hail, snowfall or thunderstorms, the system automatically moves the modules into a protected position.
This combination of renewable energy generation, operational accessibility and active weather protection makes HELIOFLEX® particularly suitable for infrastructure facilities with high requirements for safety and availability.
While Frankfurt-Niederrad is not among the largest HELIOFLEX® installations, it is one of the most technically demanding. The successful completion of the project demonstrates that existing infrastructure can be transformed into valuable renewable energy assets even under challenging structural and regulatory conditions.
The project highlights the potential of HELIOFLEX® to support the energy transition by unlocking previously unused infrastructure areas while fully preserving their original purpose.