The integration of photovoltaics into buildings represents the preferred route in Switzerland, given the country’s urban density. The Freesuns company specializes in the design of solar tiles blending into traditional roofs and has just completed the renovation of three historic buildings in the city of Neuchâtel.
October 21, 2024 Gwénaëlle Deboutte
Roofs with irregular curves and slopes pose a challenge to the standardized dimensions of conventional solar panels. This becomes even more complex when it comes to protected or historic buildings. In Switzerland, the integration of photovoltaics into buildings represents a preferred path given the human density, highly concentrated in cities. However, according to a census carried out in 2018 by the Federal Statistical Office (FSO)out of a total of 1.8 million buildings in Switzerland, more than 270,000 monuments are classified as buildings of particular interest with a view to their preservation (i.e. 15% of the built heritage in Switzerland). 75,000 of them are classified as historic monuments and protected by law (i.e. more than 4% of buildings).
To exploit this potential, the Swiss designer of solar tiles Freesuns, based in Colombier-sur-Morges, has been targeting this market since 2016, whether in the residential, municipal or commercial segments. For example, its Solaris VDiamond Terracotta tile, with an output of up to 97 Wp/m2, aims to reproduce traditional Swiss heritage roofs with a range of terracotta toned colors. The Solaris Heritage range, with power of up to 138 Wp/m2, imitates slate tiles and is suitable for new or existing buildings.
Solar roof of the Collège des Parcs in Neuchâtel.
Image : Freesuns
For its latest project, Freesuns tackled three renovation projects for protected buildings in the canton of Neuchâtel. They include the Collège des Parcs, belonging to the city of Neuchâtel as well as the school building on rue des Beaux-Arts and the university building on rue A.-L. Breguet belonging to the Canton. For the Collège des Parcs, a century-old building, the municipality had to carry out major sanitation and upgrading work but wanted to respect its exterior and interior architecture, while improving its energy balance. The solution therefore consisted of installing a 192 kWp roof with Solaris Premium Black tiles. Measuring 700 x 460 mm, they are pre-cut into different shapes which allow them to adapt to the configuration of the roof. A power optimizer is dedicated to a group of 10 to 20 tiles maximum, to minimize the impact of shading on the performance of the plant. Each tile, guaranteed for 10 years, includes four PERC 5BB monocrystalline cells. The college will therefore benefit from energy self-production of nearly 150,000 kWh of electricity per year, allowing it to cover its energy needs.
As for the cantonal buildings, they will respectively benefit from an installed power of 130 kWp and 95 kWp with Solaris Heritage solar tiles, also in PERC monocrystalline, for a power of up to 138 Wp/m2, which can be installed by roofers on a standard wooden frame. They are manufactured in a glass-to-glass configuration using tempered glass with anti-reflective coatings. In total, 33,300 solar tiles were installed on the three buildings. “We hope that these pioneering renovation projects will be an inspiring model for other townships and municipalities. They perfectly illustrate the balance between respect for heritage and sustainable development,” underlines Deborah Learoyd, Managing Director of Freesuns.
67 kWp curved solar roof in Meggen.
Image : Freesuns
This technology was developed with the assistance of the Swiss public-private technological innovation center CSEM. It is in its laboratory that all the characterization tests but also mechanical resistance, aging and fire resistance were carried out. Last March, to continue its research and development work in the areas of its design software and hardware, the company raised one million Swiss francs (1.07 million euros) from a consortium composed of investors, including Phida Group, a Swiss player in the building envelope sector.
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