Brunel Solar Team holds on to lead after nail-biting duel

Telowie, 27 August 2025 – The fourth race day of the Bridgestone World Solar Challenge has come to an end and was all about sailing on the wind for the Brunel Solar Team. Thanks to the two innovative fins on solar car Nuna 13, the team managed to hold its ground against competitors from Belgium and Twente, while the shifting weather conditions of the sun, clouds, and rain made the battle even more challenging. With the finish line in Adelaide in sight, the three leading teams are preparing for the decisive final day.

The morning started off fresh and windy. The first control stop at Cooper Pedy came just 20 km after the start of the day, where Nuna 13 was the first to arrive. Team members formed a protective wall around Nuna so the solar panel wouldn’t catch too much wind while charging. Rivals Solar Team Twente and Belgium’s Innoptus Solar Team followed just a few minutes behind. By the third control stop, the tension had risen further: “Today was a constant battle with our competitors,” says Henk Wallenburg, structural engineer at the Brunel Solar Team. “When we arrived at the last control stop, Innoptus Solar Team was only three minutes behind us. We discovered the front right tire was flat and decided to change it immediately after the stop. The swap went flawlessly, but it still cost us time, leaving us just seventeen seconds ahead of the Belgians at that point. With more than 200 kilometers to go, tomorrow will be nerve-wracking. A single mistake, no matter how small, could be the difference between victory or defeat.”

In the afternoon, the team faced changing weather conditions: short but heavy rain showers limited the input from the solar panel. The wet road surface made steering more difficult for the drivers. “The rain reduced visibility and cut down on our energy yield, which was a setback, but luckily it cleared up quickly,” says Jules Teeuwen, driver at the Brunel Solar Team. The wind also played a major role. Clever aerodynamic innovations, consisting of a retractable canopy fin and a manually mounted swordfin, allow Nuna 13 to effectively ‘sail’ on the wind and achieve higher speeds without extra energy consumption from the battery. “The fins give us an extra boost in these conditions. It feels just like sailing, but on wheels,” says David Mol, aerodynamicist and strategist at the Brunel Solar Team. “Every gust of wind from the right angle is an opportunity to gain speed. Our fins helped us stay ahead of the Belgians today.”