Combined shading and photovoltaic system in the fanlights of the atrium
The background
In the conceptual engineering phase of the extremely representative and architecturally appealing Head Office of Würth Holding, the planning team faced a particular challenge:
The building's high energy input during the summer months, due to the large amount of glass used in the façade, had to be reduced to avoid additional cooling loads.
At the same time, it had to be ensured that sufficient light could get into the atrium to avoid the use of artificial light during the day.
The solution
With the involvement of several experts the designers eventually developed a concept that was able to fulfil both demands:
a combined shading and photovoltaic system. The ten, roughly 12 metre long rows of fanlights in the building were fitted alternately with electrically adjustable blinds and fixed, semi-transparent photovoltaic modules.
CIS modules in a semi-transparent striped design
This arrangement created a visually appealing chessboard pattern for the entire fanlight system.
All CIS shading elements have a ventilation system. This prevents the radiated thermal energy from entering the building.
Within the framework of a coordinated energy concept adjustable glass slats were installed in the façade in addition to the fanlight solution. The overall strategy enables optimum regulation of the light and the radiation conditions within the atrium, effectively blocks thermal energy entering the building and also generates electricity.
Cables concealed in the cavities of the clamps
CIS in use
The photovoltaic shading elements have a striped design with a strip width of <1 cm. Each module was produced specifically according to the building physics specifications for transmission and the G-value.
Even in the conceptual engineering phase it was very important that the shade caused by the striped design would be diffused. This avoided potential irritation for visitors (Allen Effect) right from the outset.
The trapezoidal shape of the atrium meant that eleven different sizes of photovoltaic modules had to be used.
Fascinating interplay of the shading and photovoltaic system
The glass for the photovoltaic shading elements was designed so that spans of up to 1,650 mm were possible and that the elements could be fixed on the top side. This creates the impression of an aesthetically uniform glass area uninterrupted by clamps.
Each photovoltaic module was produced with the same working voltage and was connected in series with the other modules. The solar energy is provided to the building by means of an inverter.
„To complement our environmentally friendly building management systems our aim was also to employ leading edge technology in the energy generation system.
We were able to implement this project with Würth Solar as a strong partner.
We determined that the roof of our building was the best location for the installation. One of the main challenges was to resolve the shading problem. Ten rows of fanlights are installed in the flat roof, which provide natural light in the top floor and down to the open atrium on the ground floor.
Consequently, the system could not darken the windows. But this requirement was fulfilled wonderfully with, what to date, is a unique design of CIS elements. We are convinced that this combined use of photovoltaics, energy generation and shading will become popular in addition to all the traditional applications.
The system has worked perfectly since it was installed. We are proud to have such an innovative photovoltaic system installed in our building.“
(Felix Steiger, Project Manager Würth Holding, Chur)
The technology
- Number of modules: 125
- Width (mm): 3000 / 600 / 450 / 300 / 150
- Length (mm): 1650 / 1550 / 998
- Total output installed: 3.7 kW
- Light transmission of the CIS modules: 50%
- G-value (@ 50% light transmission)
- Module design: 10 mm ESG front glass (solar glass)
