Covestro Ӕthon
After two years of development and manufacturing, we are proud to present the fifth generation of our Sonnenwagen, Covestro Ӕthon. This vehicle marks the beginning of a new chapter for Team Sonnenwagen, as we face an unprecedented challenge: for the first time, the Bridgestone World Solar Challenge will take place two months earlier than usual. With significantly different weather and light conditions, this shift required us to rethink our approach and adapt every aspect of our car. Covestro Ӕthon is the result of countless hours of optimization, designed to meet these unique circumstances with maximum efficiency, reliability, and performance.
2025
Build year
Mono-Si cells &
Perovskite cells
Type of solar cells
3 kWh
Battery pack
138 km/h
Top Speed
6 m²
Area of the solar array
3
Number of wheels
<200 kg
Total weight
≈ 27 %
Efficiency of the solar cells
NMC
Battery technology
Explore Covestro Æthon in 3D
The Covestro Æthon is more than a race car, it is a high-tech test lab on wheels engineered to conquer the grueling 3,000 km across the Australian Outback. To withstand these extreme conditions, we worked with our partner Covestro to integrate advanced, lightweight polymer materials into the vehicle’s core.
Click on the annotations in the 3D model to explore the exact spots where these innovations maximize battery safety, provide vital driver protection, and prove that sustainable, circular materials belong on the racetrack.
For the best viewing experience, please select “HD” in the 3D viewer under Settings → Textures.
Technical highlights.
Aerodynamics
This year, a major regulation change for the Bridgestone World Solar Challenge increased the allowed solar cell area from four to six square meters. This completely shifted our workflow. Our team focused on finding the perfect balance between maximizing solar energy collection and keeping aerodynamic drag as low as possible. Through intense simulations and countless iterations, we optimized the final shape of the Covestro Æthon—significantly improving aerodynamic stability to safely withstand the strong crosswinds of the Australian outback.
Structure
Our team engineered composite components to withstand all potential loads while keeping the car as lightweight as possible. To achieve this, the large body was split into individual parts to fit our CNC machines and autoclaves. Despite a tight schedule with two months less preparation time, we milled 55 pieces and completed 21 vacuum infusions right on time. To ensure maximum driver safety, the monocoque is reinforced with a Kevlar-Carbon hybrid prepreg layer and energy-absorbing foam blocks.
Electrical Engineering
To bring Covestro Æthon to life, our electrical department optimized energy collection for Australia's low winter sun by placing the majority of solar cells on the car's rear. We designed a unique "Tandem-Tandem lid" combining silicon cells around the canopy with newer Tandem-Perovskite cells at the back, achieving an efficiency of up to 27%. Despite a major rule change limiting capacity to 3 kWh instead of a weight limit, our self-developed battery now features a smart modular design for easy testing replacements. Additionally, we upgraded our custom axial flux motor, significantly improving both its efficiency and mechanical ruggedness.
Mechanical Engineering
To turn the chassis into a race-ready vehicle, our team adapted the suspension system to the car's larger dimensions, increasing both wheelbase and track width for enhanced stability. This required redesigning the steering system with wider-opening wheel covers and larger steering angles, achieved through close collaboration with the aerodynamics department. For the first time, sensors for measuring suspension travel and acceleration have been fully integrated into our system. This allows us to instantly evaluate our design choices and lays a crucial foundation for future data-driven improvements.
Driving Strategy
Our driving strategy department joined forces with the aerodynamics team during the design phase, using simulations to balance a flat solar array for optimal sun exposure with an efficient shape. During the race, the team will travel directly behind Covestro Æthon in the "Chase" vehicle. From there, they maintain a constant data exchange to monitor energy consumption and battery health in real-time. Combining this with precise weather forecasts, the team makes critical, real-time decisions. Facing a winter race and a battery half the size of last year’s, this strategy is more vital than ever to finish first in Adelaide.
