1999 design becomes reality: Mercator II is getting a colored solar façade

This technology has been further developed in recent years. Soluxa, a spin-off from Radboud University (Department of Applied Materials Science), developed a technique to add color to solar panels while maintaining their efficiency. In collaboration with the architect and the façade contractor, an invisible mounting method was devised to ensure full integration into the façade of the Mercator II building. What was the underlying concept behind this building design? And what specific technology did Soluxa develop that enabled De Ruiter to finally complete ‘his building’ more than 25 years later?

A colored solar façade

Thirty years ago, Paul de Ruiter was already researching the possibility of making buildings energy-positive. As an emerging architect in 1994, he was commissioned by the university to develop a number of energy-efficient buildings for what would become the Mercator Science Park. These were research buildings featuring labs and office space for startups. De Ruiter ultimately delivered two buildings: the glass Mercator I and the silver-colored high-rise Mercator II.

Paul de Ruiter: “At the time, the south side of Mercator II was designed so that the entire façade could be fitted with solar cells, with the aim of making the building energy-neutral. That wasn't feasible back then. Now, however, the time is right, and we are going to cover the entire façade with solar cells. The Nijmegen-based startup Soluxa developed something very clever: a color coating that can be applied to the panel without significant loss of efficiency. It is a truly brilliant solution - a ‘Columbus’s egg’- because you can purchase state-of-the-art solar cells and coat them in a wide range of colors.” A unique silver-gray color was developed for Mercator II to preserve the look of the original aluminum façade panels.

Nanotechnology

How does the technology behind the colored solar panels Paul de Ruiter refers to actually work? Standard solar panels are dark because this allows them to absorb as much light as possible. If you were to apply color to a solar panel using ordinary paint, the light would be lost for energy generation, and the panel would cease to function (or barely work at all). Soluxa utilizes an interference coating based on nanotechnology. Instead of absorbing light, this coating reflects only the desired wavelength (the color) by precisely tuning optical layers to one another. All other light simply passes through to the solar cell. This gives the panel a visible color while still retaining 80–98% of the efficiency of a standard black panel for most colors.

Broader applicability

One of the major advantages of colored solar panels is the combination of aesthetics (color) and function (energy yield). Many people consider traditional black panels ugly or unsightly. With this new technology, colors can be customized, making the panels suitable for a wider range of applications, such as integration into building facades. This increased versatility comes at an opportune time, as the so-called BENG3 regulations require new buildings to generate at least 40 percent of their own energy consumption. Rooftop panels are often insufficient for this purpose; solar facades can offer a solution by providing additional surface area.

Benefits of solar facades for the grid

Another advantage is that solar facades help relieve the strain on the electricity grid. South-facing rooftop panels primarily generate energy around midday, creating peak loads on the grid. This can lead to grid congestion—an issue that is currently unavoidable. In contrast, panels on east- and west-facing facades capture the morning and evening sun, precisely when energy demand is highest. A combination of rooftop and facade solar panels results in a more balanced and smarter energy profile. The only downside? The investment cost for a solar facade is slightly higher than for traditional cladding. However, the cost is recouped within a few years thanks to the energy generated.

Innovative project

The integrated solar facade at Mercator II, featuring Soluxa’s coloring technology, is an innovative project in many respects. It was realized with the help of the Demonstration Energy and Climate Innovation (DEI+) subsidy from the Ministry of Economic Affairs and Climate Policy; this underscores the campus’s role as a ‘living lab’ and will help make solar facades a viable option for new construction and facade renovation. Moreover, the solar facade features a unique, specially developed aluminum-colored finish, and in terms of scale, it will be one of the largest colored solar facades in Europe! Work begins in mid-August. The solar facade is scheduled to be connected to the electricity grid around November, at which point it can begin operating.

Solar façade sustainability factsheet

• Mercator II: completed in 2001
• Number of solar panels: 252 colored solar panels
• Dimensions: 1762 x 1134 x 30 mm per panel
• Color: approximation of RAL 9006, based on Soluxa Vibrant coating
• Multifunctional use: the solar panels generate electricity while simultaneously serving as façade cladding
• Improved exterior shell insulation: achieved by replacing existing insulation with a thicker layer of glass wool
• Power output: approximately 340 Wp per panel. Consequently, a colored panel delivers about 70% of the output of a black panel (480 Wp)
• Expected yield: approximately 65,000 kWh per year. The generated electricity is fully utilized on campus and is equivalent to the annual electricity consumption of about 25 households. Due to the vertical orientation, the yield is relatively favorable in winter, when electricity demand is higher and the low-hanging sun strikes the panels at a relatively perpendicular angle.
• CO₂ reduction: approximately 12,000 kg of CO₂ per year attributable to the panels

Partners involved

Paul de Ruiter Architects, Soluxa, Campus & Facilities, Kuijpers, Plegt-Vos, Flow Gevelbekleding, and SFS

This project was made possible in part by a Demonstration Energy and Climate Innovation (DEI+) grant from the Ministry of Economic Affairs and Climate Policy.