Solarbay opacifying sunroof : Spectacular innovation born from a unique joint-development

Escape. Take to the road with passengers’s head in the clouds, in a light-filled cabin unobstructed by the sun. The experience aboard Renault Rafale and Scénic E-Tech electric equipped with the Solarbay opacifying panoramic glass roof is unique. Because as well as providing excellent thermal comfort and optimum light levels on board, it protects against the sun by darkening on demand, either in its entirety or in halves, in a fluid movement over nine segments. All in a matter of seconds. The effect is striking, to say the least.

A perfect illustration of the innovations that make Renault models "cars for living", this magical glass roof is the result of an unprecedented joint development project between Saint-Gobain and Renault.

Demanding specifications for Solarbay

“The Solarbay opacifying sunroof uses PDLC (Polymer Dispersed Liquid Crystal) technology,” explains Tim Jurkowski, VP Sales, Marketing, and Projects at Saint-Gobain. Used in the construction industry, this opacification technique is based on the displacement of molecules caused by an electric field. In the car industry, only premium manufacturers have used this technology for opaque glass roofs. Renault is the first generalist manufacturer to do so, adding the function of partial and segmental opacification. "To meet Renault's ambitions for its new models, Saint-Gobain Sekurit took up the challenge of adapting it to the interiors of several vehicles" adds Tim.

This was one of the constraints in the engineering specifications drawn up for Saint-Gobain. “Circuitry for sunroof opacification had to be easy to install on a range of vehicles. In addition, we wanted the innovative feature to be rolled out on several new models in succession, what we call the ‘wave effect’. Not to forget we also had a tight schedule,” says Patrice on Renault’s side.

More than meets the eye

While the PDLC opacification technology used in the Solarbay opaque glass roof is undoubtedly the most spectacular for all passengers, the technology used to ensure thermal comfort on board is no less remarkable.

A special coated glass is used to protect passengers from temperature variations and the "icicle" effect in winter and the "sauna" effect in summer when entering the car. “A first layer, 100 times thinner than a stand of hair, reflects most of the infrared radiation from the sun’s rays. A second layer stops heat from entering the vehicle interior in summer, and from escaping the car in winter,” explains Tim.

The glass is made using nearly 50% recycled glass from scraps that come from automotive glass production. This was an obvious choice to make for Renault and Saint Gobain, two companies actively working towards the energy transition and striving to ensure a better-preserved environment.

A unique joint-development between Renault and Saint Gobain Sekurit

During the Solarbay co-development period, meetings between the various working groups were held one after the other. Dedicated joint teams of more than 100 people worked in agile mode to coordinate the development of the glass roof with vehicle development. The Renault teams work with the vehicle architecture teams to integrate the roof so that it is as large as possible (1,470 x 1,117 mm on Rafale).
As for Saint-Gobain, “the challenge was to keep a close eye on both product development and vehicle development, while respecting Renault’s deadlines and quality requirements,” Tim recalls.
Having a fostered a trust-based relationship and guided by Renault's specifications, Saint Gobain succeeded in developing a discreet control box in the ceiling light to control the opacification manually.

Solarbay is a perfect illustration of Renault's ambition to develop technologies that are useful and accessible to as many people as possible by teaming up with the best.