World Solar Challenge
The World Solar Challenge, named the Bridgestone World Solar Challenge since 2013, is an international event for solar powered cars. The course is over 3,022 Kilometers through the Australian outback, from Darwin in the Northern Territory to Adelaide in South Australia.The event was created in 1987 to encourage the development of solar-powered vehicles and has been held fifteen times over its 32-year history.
The World Solar Challenge is usually held every two years, but the 2021 event was canceled because of the COVID-19 pandemic, causing a four-year gap between the 2019 and 2023 events. The event was initially held once every three years, and became biennial from the turn of the century.
The WSC attracts teams from universities, corporations, and high schools around the world. Team from Delft University of Technology, known as the Nuna team and cars, have won eight out of twelve races since 2001.
Since 2007, the WSC has included multiple vehicle classes. In 2013, a radically new "Cruiser Class" was introduced, promotes the technological development of practical, road-legal, and multi-seater solar vehicles. The speed of competing cars has increased from an average speed of in 1987 to in 1996, to by 2005.
Objective
The objective of the challenge is to promote the innovation of solar-powered cars. It is a design competition at its core, and every team/car that successfully crosses the finish line is considered successful. Teams from universities and enterprises participate. In 2015, 43 teams from 23 countries competed in the challenge. Except Nuna team and cars from Delft University of Technology, team from Delft University of Technology, known as the Nuna team and cars, have won eight out of twelve races since 2001. The Tokai Challenger, built by the Tokai University of Japan, won in 2009 and 2011. The Belgian formerly known as the Agoria Solar Team from KU Leuven University won in 2019 and 2023.Remarkable technological progress has been achieved since the General Motors led, highly experimental, single-seat Sunraycer prototype first won the WSC with an average speed of. Once competing cars became steadily more capable to match or exceed legal maximum speeds on the Australian highway, the challenge rules were consistently made more demanding and challenging — for instance after Honda's Dream car first won with an average speed exceeding in 1996. In 2005 the Dutch Nuna team were the first to beat an average speed of.
The 2017 Cruiser class winner, the five-seat Stella Vie vehicle, was able to carry an average of 3.4 occupants at an average speed of. Like its two predecessors, the vehicle was successfully road registered by the Dutch team, further emphasizing the great progress in real-world compliance and practicality that has been achieved.
Challenge strategy
Efficient balancing of power resources and power consumption is the key to success during the challenge. At any moment in time, the optimal driving speed depends on the weather forecast and the remaining capacity of the batteries. The team members in the escort cars will continuously remotely retrieve data from the solar car about its condition and use these data as input for prior developed computer programs to work out the best driving strategy.It is equally important to charge the batteries as much as possible in periods of daylight when the car is not driving. To capture as much solar energy as possible, the solar panels are generally directed such that these are perpendicular to the incident sun rays. Sometimes the whole solar array is tilted for this purpose.
Important rules
- The timed portion of the challenge stops at the outskirts of Adelaide, 2998 km from Darwin. However, for the timings recorded at that point to count, competitors must reach the official finish line in the centre of the city under solar power alone.
- As the challenge utilises public roads, the cars have to adhere to the normal traffic regulations.
- A minimum of 2 and maximum 4 drivers have to be registered. If the weight of a driver is less than, ballast will be added to make up the difference.
- Driving time is between 8:00 and 17:00. In order to select a suitable place for the overnight stop it is possible to extend the driving period for a maximum of 10 minutes, which extra driving time will be compensated by a starting time delay the next day.
- At various points along the route there are checkpoints where every car has to pause for 30 minutes. Only limited maintenance tasks are allowed during these compulsory stops.
- The capacity of the batteries is limited to a mass for each chemistry equivalent to approximately 5 kWh maximum. At the start of the route, the batteries may be fully charged. Batteries may not be replaced during the competition, except in the situation of a breakdown. However, in that case, a penalty time will apply.
- Except for the maximum outer dimensions, there are no further restrictions on the design and construction of the car.
- The deceleration of the dual braking system must be at least 3.8 m/s2.
Rule evolution
- By 2005, several teams were handicapped by the South Australian speed limit of, as well as the difficulties of support crews keeping up with solar vehicles. It was generally agreed that the challenge of building a solar vehicle capable of crossing Australia at vehicular speeds had been met and exceeded. A new challenge was set: to build a new generation of solar car, which, with little modification, could be the basis for a practical proposition for sustainable transport.
- Entrants to the 2007 event chose between racing in the Adventure and Challenge classes. Challenge class cars were restricted to 6 square meters of Si solar collectors, and later to 3 square meters for GaAs, driver access and egress were required to be unaided, seating position upright, steering controlled with a steering wheel, and many new safety requirements were added. Competitors also had to adhere to the new speed limit across the Northern Territory portion of the Stuart Highway. The 2007 event again featured a range of supplementary classes, including the Greenfleet class, which features a range of non-solar energy-efficient vehicles exhibiting their fuel efficiency.
- For the 2009 challenge class several new rules were adopted, including the use of profiled tyres. Battery weight limits depend on secondary cell chemistries so that competitors have similar energy storage capabilities. Battery mass is now 20 kg for Li-ion and Li-polymer battery.
- In 2013, a new Cruiser Class was introduced. After the German team of competed with a four-wheeled, multi-seat car, the BoCruiser, in 2013 a radically new "Cruiser Class" was introduced, stimulating the technological development of practically usable, and ideally road-legal, multi-seater solar vehicles. The route took place in four stages. Final placings were based on a combination of time taken, number of passengers carried, battery energy from the grid between stages, and a subjective assessment of practicality. Since its inception, Solar Team Eindhoven's four- and five-seat Stella solar cars from Eindhoven University of Technology won the Cruiser Class in all four events so far.
- In the 2015 Cruiser Class regulations, the scoring formula emphasized practicality less than before. Elapsed time will account for 70% of the score, passengers 5%, grid energy use 15%, and practicality 10%.
- In 2017, solar array areas were reduced, and the Cruiser Class was changed to a Regularity Trial, with scoring based on energy efficiency and practicality.
- In 2025, to slow down the race and show that solar cars are feasible even during winter, the race was shifted by two months to the end of August. To add more emphasis on the solar aspect of the challenge, the solar collector area was also increased to 6 m2 while limiting the battery pack capacity to 11 MJ.
History
After the 4th event, he sold the rights to the state of South Australia and leadership of the event was assumed by Chris Selwood.
The event was held every three years until 1999 when it was switched to every two years.