Mercedes-Benz/Webasto: More Light - How Solar Technology Boosts Range

When Audi equipped its luxury limousine A8 in the mid-1990s with an electric sunroof on request, which could supply the air conditioning with solar energy even when parked, it seemed like a leap into a promising automotive future. At least in the summer, no more getting into the blazing hot interior, but instead a slightly cooled leather interior, allowing you to start right away without breaking into a sweat. Over the past decades, there have been repeated attempts to utilize free solar energy as efficiently as possible in cars. Since electrified vehicles have gained increasingly significant importance, and car developers are fighting for every kilowatt-hour that can either be saved or ideally recovered, solar energy has come back into focus more than ever.

The now discontinued Fisker Ocean had a special solar roof that supplier Webasto had developed elaborately. With sufficient sunlight, the attractively designed roof structure of the electric SUV, developed with the help of Magna, could collect countless sunrays in everyday operations, which should have been enough for an additional 2,500 kilometers per year. But the Fisker dream burst, and development partner Magna and technology supplier Webasto, as well as the customers, were left out in the cold.
 

Polycarbonate Sheet Over the Rear

But at least at Webasto, they still believe in solar energy. The supplier recently introduced the Eco Peak, a test vehicle whose polycarbonate sheet not only covered the vehicle's roof but, similar to the technology carrier of the electric Mercedes EQXX, also encompassed the rear window. The correspondingly enlarged area was equipped with solar cells that supply the vehicle with up to 350 kWh of electricity per year.

"It's not always just about the pure utility. A modern, attractively designed solar roof from Webasto is a statement for sustainability and the environmental consciousness of the vehicle buyer," explains Jan-Henning Mehlfeldt, responsible for the roof business at Webasto.

Since there is currently a lack of demand from automakers for solar roofs, the roof specialist near Munich is currently focusing on lighting installations, switchable shading, and sensors for driver assistance systems that are installed on the car roof.

Do Not Leave Solar Energy Unused

However, Mercedes does not want to let solar energy go unused in the medium term and has developed a solar coating for its vehicles that could generate electricity for several thousand kilometers in a few years. This is made possible by an extremely thin film applied to the vehicle's paint. At a thickness of five micrometers, it is thinner than a human hair and weighs just 50 grams per square meter of vehicle surface. The advantage: the film is not only light but can be flexibly applied to all body modules without altering the design of the vehicle, as the photovoltaic surface can be applied to almost any substrate. In preliminary development, the thin solar cells have an efficiency of a solid 20 percent. A mid-size crossover with a paint surface of eleven square meters could produce free energy for up to 12,000 kilometers per year under appropriate sunlight.