Bonding the World’s First Retractable Solar Roof

A fully automated metering and mixing system is helping to create retractable solar roofing systems in Switzerland and Germany.

Parking spaces, logistics areas, and wastewater 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.

The world’s first patented retractable solar roof was developed under the name Horizon by dhp technology AG. In 2018, the first car park model went into operation at 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% of the electricity demands of the energy-intensive wastewater treatment plant. The entire system remains fully accessible, and the retractable solar roof provides shade during necessary maintenance work in summer while also reducing algae growth.

Focus on Automation

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 for use or folded up and stored in a garage during inclement weather. The lightweight system consists of a galvanized support structure and the roof made of solar modules suspended from supporting cables.

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 that 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.

Eldomix conveys the two components by means of two gear-metering pumps. The pumps are driven by three-phase asynchronous motors and offer high metering precision. The material is supplied directly from the original container by means of two drum pumps. In general, eldomix is suitable for processing low- to medium-viscosity multi-component materials based on polyurethane, epoxy, or silicone. The material is homogeneously mixed via a static mixing system; the mixing ratio and the discharge quantity are variable.

The material can be discharged in shot form or continuously via a dispensing valve. In this way, the photovoltaic modules can be safely and reliably bonded to the metal frame and then assembled into a high-quality retractable solar roof. The production line is running at full capacity, and more retractable solar roof systems will soon follow in Switzerland and Germany.