Don’t underestimate the Sun

Around nine billion tons: that's how much carbon dioxide global transport produces every year – roughly a quarter of all energy-related CO₂ emissions. The challenge is clear: mobility must become more climate-friendly and more efficient. The more interesting question is: how do we get there?

Right now, electric cars are in the spotlight. In 2025, more than 20 million of them were sold worldwide – one in four newly registered passenger cars now has a battery on board. And the technology is once again front and center on the annual World EV Day.

But there's one thing we shouldn't overlook: the mobility transition needs more than one answer. The requirements for a city bus, a passenger car, a long-haul truck, or an aircraft differ considerably – and may call for drive systems other than the electric motor.

More than one drive type

That's why, alongside batteries, hydrogen and synthetic fuels are also part of the mix. And increasingly, an energy source that was previously associated with niche applications is coming into view: the sun. This topic is examined in more detail in the latest Covestro web-talk.

Vehicle-integrated photovoltaics, or VIPV for short, turns the vehicle surface into part of the energy system. How large its contribution can be depends not only on the vehicle type but also on location and usage. According to the European SolarMoves report from 2025, VIPV could cover up to 50 percent of a passenger car's annual energy demand in Madrid, and up to 35 percent in Amsterdam.

This doesn't mean, of course, that every car will run exclusively on solar energy in the future. Rather, the key point is that solar power can already be relevant even if it only covers part of the energy supply. In combination with other drive types, it can provide additional range, reduce charging needs, or power auxiliary systems.

The body becomes a power plant

Commercial vehicles are particularly interesting here: large roof and body surfaces offer the potential to use solar energy directly during operation. For example, a solar system on a Ford E-Transit in Northern Europe covered around 12.5 percent of its total charging energy in a one-month test. The value of VIPV lies not only in potential CO₂ savings. Vehicles that generate part of their own energy can become more independent of charging infrastructure and take the strain off local power grids.

At the same time, limits remain: available surface area, solar irradiation, efficiency, and costs. And this is where the next challenge begins – how efficiently does a vehicle use the energy available to it? Weight, aerodynamics, thermal management, battery safety, and material selection all come into play here.

This is exactly where Covestro comes in – as a materials developer delivering solutions for precisely these requirements. For example, in the "Sonnenwagen," the solar car built by the student team of the same name from Aachen. At the World Solar Challenge, the solar racing car recently covered more than 3,000 kilometers through the Australian Outback powered exclusively by solar energy. Under these conditions, every gram and every watt-hour saved counts. And so does the question of which materials can meet several requirements at once.

A laboratory on wheels

This is exactly what the Sonnenwagen team and Covestro are working on together. The students bring their deep understanding of the vehicle and specific technical requirements, while Covestro contributes its materials and application expertise. Together, they discuss, test, and refine solutions – for lightweight construction, battery and thermal management, or the protection of sensitive components.

More than ten Covestro materials are used in the current model, the "Covestro Æthon." These include chemically recycled polyurethane foam from end-of-life car seats in the driver's seat and a coating that cures at room temperature, saving energy.

In this way, the solar car becomes a laboratory on wheels – for solutions that could later find their way onto our roads. And they show that the future of mobility hinges on the right materials.