Making clever use of the sun

Parking spaces, logistics areas and waste water treatment plants require a lot of space.

Why not make efficient use of this space? This is what the Swiss start-up dhp technology thought when it constructed the world’s first retractable solar roof. The individual modules are manufactured with dispensing technology from DOPAG.

At the car park for Kronberg cable car system in the Swiss canton of Appenzell Innerrhoden, visitors have a pleasant surprise in store. They can park in the shade and charge their electric vehicles at the same time. The 4,000 m² car park is covered by a retractable solar roof. This provides power to the Kronberg cable car system, which climbs from the valley to the mountain station situated at approximately 1,600 metres. During stormy weather, hail or snowfall, the solar modules fold up by themselves and are stored in long garages. The world’s first patented retractable solar roof was developed under the name Horizon by dhp technology AG. The car park roofing is one of the latest projects from the young Swiss company based in Zizers in the canton of Graubünden. This all began with the roofing of wastewater treatment plants. In 2018, the first model went into operation in the wastewater treatment plant for the town of Chur. It was the first installation of its kind in the world. With an area of 6,400 m², the retractable solar roof covers 20 per cent of the electricity demands of the energy-intensive wastewater treatment plant. The benefit of this is that the entire system remains fully accessible, and the retractable solar roof provides shade during necessary maintenance work in summer and reduces algae growth.

Focus on automation

Managing directors Gian Andri Diem and Andreas Hügli

Managing directors Gian Andri Diem and Andreas Hügli (Picture: dhp technology)

The retractable solar roof has a system control function with an integrated meteo algorithm. In connection with data collected by a weather station mounted on the system, the modules are either unfolded or, during inclement weather, folded up and stored in a garage. Managing directors Andreas Hügli and Gian Andri Diem have found a niche in the market with this business idea. The pair turned to cable car technology for the flexible photovoltaic roof. The lightweight system consists of a galvanised support structure and the roof made of solar modules suspended from supporting cables. These are made from non-glare plastic and connected to one another by means of hinges.

"As far as production is concerned, we have focused on automation from the very beginning, as this allows us to grow."

Gian Andri Diem

For the production of the individual solar modules, the eldomix metering and mixing system from DOPAG was integrated into the production line. It meters and mixes a dual-component adhesive which is used to bond the thin plastic photovoltaic modules to a metal frame. Application of the material is fully automated. The individual modules are then assembled into a complete retractable roof group. The company has already used a rental system from DOPAG in the production of a prototype. "The solar modules are exposed to extreme weather conditions, from strong solar radiation, wind and rain to snow and sub-zero temperatures", says Andreas Huegli.

"Stable, durable bonding of the modules to the frame is therefore vital for us. We are impressed by the precise, reliable metering and mixing technology from DOPAG."