The Haufeld multi-storey car park, located at Industriestraße 25 near the Haufeld district in Siegburg, commenced regular operation on 1 July 2026. The six-storey new build comprises approximately 500 parking spaces for cars from the second floor upwards, as well as 20 specially designated e-parking spaces. A modern parking system, equipped with licence plate recognition and digital payment options, is in use. The lower level of the car park also serves as an operating and storage area for the lorries of the Kohr company.
A specific feature of the construction project is the combination of a green roof with photovoltaic systems and an extensive facade greening covering approximately 2,800 square metres on the building side facing the city. Wi SOLAR GmbH from Kaisersesch, Rhineland-Palatinate, was responsible for the installation and commissioning of a photovoltaic system covering approximately 1,500 square metres, including the green roof substructure, on the roof of the multi-storey car park. The client for this PV project was rhenag Energie, a regionally active energy service provider from Rhineland-Palatinate and North Rhine-Westphalia. Stadtbetriebe Siegburg AöR is managing the operation of the newly constructed car park.
Innovative PV Solution and Space Efficiency
The photovoltaic system installed by Wi SOLAR consists of 602 solar modules and achieves an output of 270.9 kWp. An annual yield of approximately 251,611 kWh is forecast. This project utilised a substructure, deployed for the first time by Wi SOLAR, which ballasts and fixes the photovoltaic system onto the green roof. Typically, the substructure for PV modules is integrated into the green roof assembly and incorporated into the framework of the green roof.
Sven Endris, Managing Director of Wi SOLAR GmbH, stated that the mounting system could be adapted to the green roof's requirements during the planning phase. Thanks to the early selection and integration of the substructure, the system was designed to optimally reconcile greening, maintenance, electricity generation, and technical servicing on the roof. At the same time, an yield-optimised alignment of the modules was achieved.
The combined solution of a PV system and substructure developed by Wi SOLAR is considered efficient for planning, installation, and operation. This will lead to its continued use in future projects. Bundled planning and execution reduce interfaces, coordination, and handover processes between the trades involved. Technical detailed knowledge, responsibility, and warranty lie with a single point of contact. Maintenance of the PV system on the Haufeld multi-storey car park is carried out by Wi SOLAR through a long-term management contract, which includes regular yield and functional checks.
Thomas Beckers, Business Development Energy Services at rhenag Energie, highlighted that the photovoltaic system on the Haufeld multi-storey car park represents another energy project implemented in the region. He emphasised that the combination of a green roof and solar power generation demonstrates intelligent multiple use of limited spaces. With its installed capacity of 270.9 kWp, the system will contribute to regional renewable power generation. He expressed particular pleasure at the realisation of the project with Wi SOLAR, which marks the fifth joint project in Siegburg and underscores the importance of early coordination and holistic planning of green roofs and photovoltaics for successful implementation.
