Long before Nuna 7, the students from Delft University of Technology had made the World Solar Challenge their own. Their third car, Nuna 3, won the 2005 race. It covered the 3,021 km from Darwin to Adelaide in a record 29 hours and 11 minutes, at an average of 102.75 km/h.
The Nuon Solar Team consisted of eleven students who put their studies on hold for a year. Their adviser was Wubbo Ockels, the first Dutch astronaut, then a professor at TU Delft. Instead of starting from scratch, the team refined the winning Nuna 2 in countless details: better aerodynamics, slightly better solar cells, less weight.
The heart of the car is its triple-junction gallium arsenide solar cells, space-grade technology with an efficiency of more than 26%. Because the 2005 race took place in September, when the sun stands lower over Australia, the team even placed cells on the side wheel covers. Four MPPT trackers with more than 97% efficiency matched the panel voltage to the battery. The in-wheel motor in the rear wheel, by the Swiss company Drivetek, weighed only 10 kg, delivered more than 2,400 W and reached over 98% efficiency. The wheel covers were shaped to give extra push in a crosswind, almost like a sail.
On the road Nuna 3 reached 140 km/h on the first race day and set a daily record of 858 km. The finish in Adelaide made it the third Delft win in a row. The same team later won with Nuna 4, 5 and beyond. Many of the ideas, from hub motors to MPPT charge controllers, are the same ones we use today on DIY solar e-bikes, only at a different scale.
Technical data
| Builder | Nuon Solar Team, TU Delft (Netherlands) |
|---|---|
| Year | 2004–2005 |
| Layout | Three wheels, driven rear wheel with in-wheel motor |
| Solar | Triple-junction GaAs cells, >26% efficiency |
| Motor | Drivetek in-wheel motor, ~10 kg, >2.4 kW, >98% efficiency |
| Weight | ~189 kg |
| Result | World Solar Challenge 2005 winner: 3,021 km in 29 h 11 min, Ø 102.75 km/h |
Photos
- Top photo: Nuon Hans-Peter van Velthoven / Wikimedia Commons, CC BY-SA 2.5
- The Nuon Solar Team with Nuna 3 at its presentation in Zandv… Photo: Unknown / Wikimedia Commons, CC BY-SA 2.5
- Nuna 3 on show at a city race event in 2006. Photo: Niels Broekzitter from Piershil, The Netherlands / Wikimedia Commons, CC BY 2.0