European BIPV Case Study || Colorful Photovoltaic Curtain Wall of a Multi-Storey Car Park in Sweden

This project involved Soltech Energy installing a 60 kW solar facade on the wall of a car park in Sweden, which houses 300 electric charging points. It features a steel structure to facilitate air flow.

▲ The colored cadmium telluride solar glass used in the project was manufactured by Longyan Energy.

Airflow within the car park is important because cars emit exhaust fumes. According to the company, the facade is open, so air exchange doesn't need to be measured as it far exceeds the car park's required level. It also claims that airflow benefits the temperature of the panels.

“The facade uses semi-transparent colored cadmium telluride solar glass, which requires a certain angle of inclination. Simultaneously, it's placed on the building's wall, requiring substantial airflow exchange between the inside and outside of the wall,” said a relevant person in charge of the company. Based on the above design, the project uses a prefabricated 11-meter hot-dip galvanized steel structure. This structure allows the solar glass to be deployed at the required inclination angle before the structure is connected to the wall and provides the necessary air passages for the car park walls through gaps between the rows of solar glass.

▲ The prefabricated 11-meter hot-dip galvanized steel structure

According to the person in charge of Soltech Energy, this structure and module configuration facilitates simple, high-quality, and fast installation, as it only took about a month and a half to install and put the car park project into operation. It also ensures that the cell wires of the cadmium telluride solar glass are invisible from more than 2 meters away; only the colored effect of the solar glass is visible.

“The glass isn't colored; the fine black lines are the sub-cells of the cadmium telluride solar glass, but you can only see them from a distance of less than two meters. If you're further away, you only see the colored effect on the solar glass,” explained the relevant person in charge. “The technology to create visual impact is quite old for ordinary patterns and is called ‘raster graphics’.

Client Wallenstam, a Swedish real estate company, wanted the area to draw inspiration from the patterns and colors of Swedish designer Viola Grå sten, who helped popularize brightly colored rya rugs in the 1950s. Raster graphics are digital images made up of tiny rectangular pixels arranged in a grid. They are usually characterized by color gradients, varying lines and shapes, and complex compositions.

▲ Four different colors of semi-transparent photovoltaic components

The colored photovoltaic curtain wall of the facade powers the car park, which has approximately 300 electric vehicle charging boxes. The system comprises 1096 pieces of cadmium telluride colored translucent solar glass with 40% light transmittance. This product is provided by Longyan Energy, a Chinese cadmium telluride photovoltaic component manufacturer, and comes in four colors: red, blue, orange, and green.

The person in charge of Soltech Energy finally stated that the photovoltaic facade concept can be compared to any decorative facade. “You can have it as an open facade in a car park, but you can also have it as a decorative facade on a building and then add a closed facade behind it.”