Learned from nature

HAMLAR/Germany. Red, green, blue – colors evoke individual associations in people. They remind people of their first car, the first ice cream in summer, or their favorite jeans. Even if colors are subjective, they leave a lasting impression.

This effect is deliberately used in architecture. Design and color play an essential role and give buildings their unique character. The solar-active façade system from ENVELON supports this effect. With its diverse color palette, ENVELON allows the entire building to be branded with an unmistakable solar architecture that will be remembered.

The solar company does not “just” apply paint to the glass module but also uses a special coating technology that ensures that light penetrates the colored glass modules to the greatest possible extent and that the solar energy is utilized optimally.

Mike Oertel, Development Engineer at ENVELON, was involved in developing the color technology and explains what effect ENVELON has harnessed from nature.

The secret: Interference

Thanks to a unique color technology, ENVELON façade systems can be colored individually. Unlike other solar façade cladding, we do not use paint in the actual sense. Instead, we use the remarkable properties of sunlight and glass to activate the façade’s color.

The secret is interference, a cumbersome word for an effect that everyone has undoubtedly encountered in their day-to-day lives. For example, it is why soap bubbles shine brightly, or eyeglass lenses can be anti-reflective.

This is due to interference, i.e., the superposition of different waves and their reflection. When sunlight, which consists of different wavelengths, hits a thin surface – for example, the outer layer of a soap bubble – some of the light is reflected on the outside of the bubble and some on the inside. These shifting reflections lead to what is known as “interference.” Depending on the thickness of the soap bubble, we perceive different color impressions. The rest of the sunlight shines through the soap bubble's interference layer.

The ENVELON modules are designed according to the same principle: When sunlight falls onto the module, a microscopically thin interference layer reflects only a particular portion of the color spectrum at a time, so that around 85 to 95% of the light is passed through and converted into electricity by the SI cells. Depending on the selected color, the efficiency of the PV module is thus reduced by only approx. 3 to 10% compared to a black module.

This results in the particular advantage of this coating technology. If a conventional layer of paint were applied to the front glass, the SI cells would be exposed to more or less sunlight depending on the color intensity. Thanks to the unique coating technology, this is different with ENVELON: Strong colors can also be combined with high efficiency.

Shimmering like soap bubbles

In addition, the material's physical properties create a true attention-getter depending on the time of day and the light intensity of the sun: Due to the interference effect between the sun’s incoming light and the module, the color saturation of the surface varies according to the sun’s position during the day. This play of colors gives buildings with solar-active façades a special, literally “activated” envelope – and a space for creative architectural play with an inspired look. At the same time, the colored front glass is satin-finished and, therefore, glare-free so that there is no disruptive glare effect on the surrounding buildings or traffic.

Seamless building envelopes due to invisible suspension and substructure

In addition to design, architects and building owners also value aesthetic subtleties and individuality. ENVELON’s modular façade cladding meets these requirements with frameless glass elements. The mounting brackets are on the back of the PV module and are attached in an area that isn’t visible to onlookers. As a result, the suspended rear-ventilated façades offer all the building physics and design advantages of a conventional glass façade – with the added benefit of solar power generation. This is also reflected in the ENVELON system’s exceptional cost-effectiveness.

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