Powerful “sunroof”

Just under a year separated the initial idea and the grid connection of Switzerland’s most powerful rooftop photovoltaic system. Weidmüller’s know-how and experience helped achieve this record-breaking time.

Powerful “sunroof”

Powerful “sunroof” - Helion Solar, Switzerland

With the help of Europe’s largest mobile crane and the Super Puma transport helicopter, the preassembled units consisting of 20 kW inverters and photovoltaic modules were raised from the ground onto the roof and mounted on the unique steel structure.

What was being lifted here is currently Switzerland’s most powerful rooftop photovoltaic system, which has been installed on the flat roof of a production hall in the municipality of Zuchwil. The owner of the building is Swiss Prime Anlagenstiftung. The local company Helion Solar was contracted with the planning, execution and maintenance of the rooftop system.

Unique construction

“The photovoltaic system is unique in terms of its construction since it was erected on the roof of an existing production hall. A special steel structure on which the photovoltaic modules were mounted four metres high above the existing gable and shed roofs, provides easy access for subsequent maintenance work,” reports Dominik Stierli, project manager at Helion Solar. “Due to the cut-off date for the feed-in remuneration, we had a strict deadline of 30 September. We managed to stick to the tight project schedule through measures such as prefabricating the installation units. But also partners such as Weidmüller, who supported us with high standards and dedication, are a big reason behind the success of this project.”

Initial ready-to-connect solutions in no time at all

On the 36,000 m² roof area, 22,000 solar panels now generate 5.6 MW of power. That covers the demand of several thousand single-family homes - around a third of the population of Zuchwil. The CO2 savings amount to approximately 595 tonnes annually, which is equivalent to the fuel emissions of a new car driving around the globe 104 times. 284 combiner boxes assembled individually for Helion Solar helped produce this result, by reliably bundling the output from the individual strings and connecting that output to the inverter.

“When the Helion Solar project manager came to us with the request for customised combiner boxes, there were still around three months before the planned commissioning date. We told him this wouldn’t be a problem and delivered the first ready-to-connect solutions, including initial samples, within just two weeks,” reports David Schütz from Weidmüller, who supervised the project as a specialist for application-specific solutions. “Thanks to our knowledge of technical regulations in Switzerland, we were able to develop solutions for Helion Solar which are fully standard-compliant and carefully configured for the planned system architecture. Our prototypes therefore directly passed the test during the application stage. We then delivered the combiner boxes fully assembled and tested, so that the installation time on site was reduced to simply the commissioning itself.”