Belgians blitz field in big solar start

October 23, 2023
Matthew Agius is a science writer for Cosmos Magazine.

Renner Springs, NT | Belgian team Innoptus leads the Bridgestone World Solar Challenge after a chaotic and fast first day of the event in the Australian outback.

Teams dealt with 40-degree heat, bushfires off the road near Katherine and potholes and roadworks on a stretch of the Stuart Highway in the opening 9 hours of the event. All were safely navigated.

It was Innoptus and Dutch rival Brunel that performed best.

They were the only teams to clear the tiny roadside town of Elliot in the Barkly region of the Northern Territory. As a result, both crews are camping tonight on the red dirt of the Stuart Highway, nearly 800 km south of Darwin.

Innoptus Solar Team technicians point their solar array towards the setting sun near Elliott, NT. Credit: Matthew Ward Agius/Cosmos

Innoptus is the most recent winner of the 3,020km event between Darwin and Adelaide and averaged 96km/h on the opening day. That’s a fair clip – at one point the car was cruising at the Stuart Highway speed limit (110-130km/h).

These teams are among the best solar racers in the world and were always expected to be at the front, but both were surprised by just how quickly they were able to reach the lead.

“We wanted to play it safe with the qualification on Saturday, and we ended up second [in the start order] which was, really, much unexpected. It was a good place to be at,” says Innoptus’ former team manager Jarno Van Hemelen, who is providing support to the new crew at the event.

“From 50km out of Darwin, we started just driving our ‘strategy speed’ and that’s how we ended up in this place today.”

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Strategy speed, in this case, refers to a fixed pace set by team planners to optimise the solar energy captured and converted in the car’s power unit. Solar efficiency numbers are closely guarded by teams – usually, they’re around 25% of captured light converted to electricity – but even so, the myriad of other factors at play on the road, particularly temperature and wind direction, also play a part in speed calculations.

Innoptus feels its Netherlands-based rivals are pushing to keep pace with them, but Brunel’s team leadership was happy with how the day played out.

“In the end, it was way better for our strategy to keep driving the speed we wanted,” says Lennert Hessells, Brunel’s team manager. “We’re happy we’re at the front, now, with the Belgians in front of us, but we’re exactly where we want to be.”

Brunel and Innoptus expended battery energy to overtake the car of Germany’s Team Sonnenwagen Aachen, but both were comfortable with their decision to get a better road position.

Such is their speed that Innoptus advised event officials that the next control checkpoint in Tennant Creek may need to open earlier than scheduled. Already, teams are operating about 15km/h faster on average than the last event; 4 of the 6 leading teams are using new high-capacity batteries from US manufacturer Amprius.

The Brunel team’s overnight camp setup was hauled in shipping containers. Credit: Matthew Ward Agius/Cosmos

The top 4 cars are separated by 43km. In third place is Solar Team Twente, which improved from 11th at the start of the day, though how much energy was used in the process is unknown. Unlike entrants in the Cruiser class, which are allowed an optional charge in Tennant Creek and Coober Pedy, Challenger cars can only use solar electricity from their own generation.

“I would be lying if I said there was no energy wasted,” admitted Twente’s race lead Kirsten Bouwman.

“Overtaking another team costs some energy, but we planned this well and chose the right spots on the map to do so. I don’t expect we’ll overtake 8 teams again [tomorrow].”

The Sonnenwagen team is 4km further back. It led the field out of Darwin after setting the fastest time in a qualifying session on Saturday and was happy to cruise at a slower pace to force its competitors to overtake early in proceedings.

“It’s kind of what we expected to happen. We expect the other teams to go fast early, and then slow down later,” says Felix Meyer, Sonnenwagen’s driving strategist.

“We wanted to make it out of Darwin and then make them use energy to overtake us. I think this worked out pretty well.”

Teams from Tokai University and Kogakuin University in Tokyo, the University of Michigan (which started last and has leapfrogged 26 competitors) and Top Dutch Racing are currently positioned together in Dunmarra. This group is around 146km behind Innoptus.

Australia’s Sunswift Racing leads the Cruiser competition ahead of the University of Minnesota (USA) and Estonia’s Solaride team.
Bridgestone World Solar Challenge, current distances and speedsInnoptus Solar Team (BEL): 08 hours. 777km from start @ average speed 96km/h.
Brunel Solar Team (NED): 08h. 753km @ 93 km/h.
Solar Team Twente (NED): 08h. 715km @ 89km/h
Team Sonnenwagen Aachen (GER): 08h. 711km @ 89km/h.
Tokai Universirty (JPN): 08h. 634km @ 79 km/h.
University of Michigan (USA): 08h. 634km @ 79 km/h.
Top Dutch Solar Racing (NED): 08h. 634km @ 79 km/h.
Kogakuin University (JPN): 08h. 634km @ 79 km/h.
JU Solar Team (SWE): 08h. 607km @ 76km/h.
Eclipse ÉTS (CAN): 08h. 552km @ 65km/h

Full results at event website.