Day 2 dawns, at 5:30 a.m., with the Dutch ex-astronaut sitting alone in the middle of Nuna’s dark campsite, strumming a few bars of ”House of the Rising Sun” on his guitar. Sleepy, orange-clad figures emerge from the colony of canvas tents. They prop up the top half of the car’s body, with the solar array, as the first rays of the sun peek over the horizon. They roll up their sleeping bags, make Nutella sandwiches, and dust the insides of the car. ”This is the day of truth,” says Ockels. ”With an empty road and much less overtaking, we’ll see which team really is the best.”
One car from the convoy departs an hour early to collect weather data and report on road conditions—a euphemism for kangaroo roadkill. As 8 a.m. approaches, the day’s first driver, Joep Steenbeek, steps into the solar car and tightens his helmet strap. With less than 10 minutes left, the crew attaches the top, fastens cables, and tapes over the edges to smooth them against air resistance. The race official calls time, and the team waits for a looming road train to pass. The solar car slides onto the road, the motor singing its weird whine over the road train’s fading rumble.
The morning drive is smooth and sunny. Umicar Infinity coasts into the next of the race’s mandatory control stops, at Tennant Creek, 7 minutes before Nuna 4. (The control stops give reporters a chance to catch up with the solar cars and the teams an opportunity to check vehicles for wear and tear.)
But all is not well in Infinityland. An aluminum bolt holding the steering system in place has snapped, causing the rack-and-pinion gears to wear down and making steering nearly impossible. With no other option, the Belgians pull aside to repair their steering system and replace the bolt with a simple clamp, and Nuna 4 slips past them. ”Yeah…aluminum was maybe not the best choice of material for that bolt,” says Niels Burez, who oversaw Umicar’s mechanics, with a gloomy smile. ”If it wasn’t for these problems, we’d be passing Nuna, I’m sure.”
But then the weather takes a turn for the worse, as the vehicles speed into a storm brewing over Alice Springs—the midpoint of the race, and of Australia. Nuna’s suspension, strained by a persistent crosswind, finally gives in. The team stops to replace a collapsed shock absorber, surrendering 15 precious minutes. Then 80 km/h winds cause the car to yaw left so much that the left tire bursts. The unthinkable almost happens: Nuna nearly empties its battery while racing the setting sun to Alice Springs. It is forced to stop just 12 km north of the city. But when it gets there, the following morning, it is 1 hour 22 minutes ahead of the Belgian car.
The teams trickle into this odd oasis, corralled by race officials who had decided that the half-day lag between cars was bad for press coverage. Wearing a floppy hat and wraparound sunglasses, veteran solar racer Alain Chuzel examines a few vehicles in the blinding sun. Chuzel, from Phoenix, has a company, SunCat Solar, that encapsulates solar arrays for racers. Encapsulation protects the arrays from airborne pebbles and debris, which can crack cells. Because a string of cells performs only as well as the weakest in the sequence, protecting an array from damage is of utmost importance.
Usually, solar cells have minor defects, Chuzel explains. Depending on what’s needed, ”one man’s junk is another man’s gold.” Once cells are selected, they are arranged in strings and coated in special materials to make them sturdy enough to bend over a car body and withstand flying pebbles.
Hans Gochermann, who has a solar-technology company in Germany, adds another step to each encapsulation. The fanciest solar cells—mostly rejects from the International Space Station, he says—are no more than 31 percent efficient, and there’s an art to squeezing as much energy as possible out of those brittle semiconductor slices. He encapsulated the top three teams’ arrays by texturing the cell surface with matte 5-micrometer-wide pyramids. When light hits the surface, some of it is reflected. But instead of allowing light to bounce away, the pyramids deflect some of the rays back onto other pyramids, giving the photons a second chance to be soaked up and increasing the array’s power by 4 percent. The technique is particularly effective with the oblique rays of morning and evening.
Cell encapsulation is but one of several cutting-edge microindustries that have emerged to cater to solar racing. Looking for the most efficient motor controllers on the planet? You’ll find them here, most of them made by Tritium, of Woolloongabba, Australia. Tritium’s motor controller—a lightweight three-phase 20â¿¿kW inverter with supposedly unprecedented power density—came from the company employees’ own solar car experience, at the University of Queensland. The controller has a cruising efficiency of 98.3 percent, so very few of the car’s scanty supply of watts get wasted. Tritium is hoping that, having locked up the solar car market, it can now branch out into electric vehicles and grid-connected photovoltaics.
This wouldn’t be the first solar-car spin-off to become something bigger. The builders of Honda’s solar cars, which dominated the races in the early 1990s, later designed the Honda Insight, the first mass-produced hybrid car. General Motors’ solar car, also from that era, morphed into the company’s first electric effort, the EV 1. True, it was pulled from the market peremptorily, prompting conspiracy theories and a major motion picture. And mass-market success has also so far eluded New Generation Motors, an American company licensing Australian technology, whose astoundingly efficient wheel motors—at best 95 percent—are used by most solar racers.
”These are literally the engineers of the future, as in, they’re ahead of their time,” says Steven Camilleri of In Motion Technologies, another race alumnus now trying to sell uniquely efficient, lightweight motors born during his solar racing days. ”The world isn’t ready for us,” Camilleri concludes. [See ”Motor Maniac,” in this issue, for a profile of Camilleri.]
Early the next morning, the cars are released back onto the road. Some thin clouds scuttle across the sky, and an east-blowing crosswind continues to badger the teams.
”You have to look carefully at a cloudy sky,” says Hagemans, the Nunans’ logistics guru. Teams may adjust their speed to go faster through the cloudy parts and slow down in sunny patches, to give the battery pack more time to charge.
Dust storms periodically shatter the monotony of the drive. Sticks dance in the middle of the road, and seconds later a shroud of dust slams Nuna 4, throwing it off its course. A harrowing second later, the driver regains control.
The heat, the dust, and the battering force solar car designers to balance robustness and weight against low drag and rolling resistance. This year, the race’s organizers required the cars to be a shade more practical. As a result, the vehicles now have smaller arrays, normal upright seats, and ordinary steering wheels. A German entrant, Bochum University of Applied Science’s SolarWorld No. 1, with three wheels and a platypus front end, almost looks like something you’d take to pick up a few groceries. But its commodious form makes it seem bloated next to the sleek, anorexic top performers, and during the race it dawdles behind the lead cars, averaging 73 km/h. By contrast, the team proudly reports that Nuna 4 was the most aerodynamic vehicle ever tested at the wind tunnels run by DNW, a German-Dutch aerodynamics-testing facility. The Aurora 101 car also excelled aerodynamically, with a record of its own at Monash University’s wind tunnel, near Melbourne.
The Nuna convoy flies through Coober Pedy, an opal-mining town with a spectacularly lunar landscape. The wind never lets up, and that afternoon they pop the left tire four times. Each change takes less than 3 minutes for the well-practiced team, but it is clear the suspension is in peril. That night, they rebuild the left suspension, change tires, and vacuum everything in sight.
It is to be the Nuna crew’s last night under the outback’s starry skies. The next day they push—hard—to reach the outskirts of Adelaide by the 5 p.m. official cutoff. The Belgians are about 40 minutes behind them. It is a solid lead, but not an unbreakable one, and Infinity is technically a faster car. Just one small breakdown, or one miscalculation, could blow the race.
The sunset fills the enormous sky with radiant colors. The air is chilly, and the team builds a fire with a few scraps of wood they scavenge from the blank landscape. A half-dozen skeletal trees stand out in silhouette against the purple sky, improbable signposts of a greener time. The students string colored lights around the campsite and blast dance music into the deaf, endless desert.