October 15, 2017

World Solar Challenge Marks Progress Of Solar-Powered Cars

The 2017 World Solar Challenge is underway with its largest-ever field, unsurprising given the astonishing strides solar-powered and electric cars have made since the last race. The 42 teams involved aren’t about to mass market their products, but the recent explosive growth of both solar-powered and electric cars has made combining them a live issue.

The first day of the event saw Tokai University’s Tokai Challenger take the lead in the Challenger Class, where cars are judged on speed. It averaged 80.8 kilometers per hour (50.2 miles per hour) over the 322-kilometer (200-mile) first stage from Darwin to Katherine in Australia, but still had plenty of competition snapping at its heels.

Meanwhile, in the Cruiser Class, where vehicles carry a passenger and are more similar to something that could one day be road-worthy, the contest looked to be over from the get-go. The leading cruiser – the Dutch Stella Vie – scored 80 points on a system that incorporates practicality and energy efficiency. The second-ranked team had 50.5 points, despite the fact that the South Australian Minister for Tourism predicted that the Dutch team, which won the class in the last two challenges, would get “a run for their money”.

The second day confirmed the closeness of the cruiser race, with the Tokai Challenger dropping its average speed slightly and being overtaken by the Dutch Nuna 9, which was just 0.2 km/h (0.12 mph) faster. Meanwhile, among the cruisers, Stella Vie outscored the next two teams combined.

Building a solar car is still no easy feat. Tushka Hashi III barely made it out of Darwin before hitting trouble, but as the product of a high school (Mississippi Choctaw) it is perhaps more remarkable it made the race at all, later recovering and completing the second stage. In the meantime, cars with more institutional backing also spent time on the sidelines.

The origins of the competition trace back to 1982, when Hans Tholstrup and Larry Perkins did what many considered impossible – they crossed a continent in a car powered entirely by sunlight. At the time, solar panels were largely used for satellites – where most other power sources are impractical – or for applications that use only small amounts of power. Even many renewable energy advocates doubted that the then inefficient and very expensive photovoltaic cells would play a big part in the world’s future.

The success of the east-west crossing of Australia, albeit in an uncomfortable vehicle capable of only transporting one person rather slowly, inspired the first World Solar Challenge in 1987. This, like subsequent races, ran north-south from Darwin to Adelaide. It proved Tholstrop and Perkins’ achievement was no fluke, but also that solar powered cars would not be threatening the oil industry anytime soon. The first winner, GM Sunraycer, still depended on a light driver and had a frame weighing less than a heavy bicycle. Even though most of the race was under the desert Sun, the average speed of 67 km/h (42mph) suggested no one was going to be buying a solar-powered car for commuting, even if the price came down.

Then again, in 1987 putting solar panels on your roof was still almost unheard of, and electric cars were mostly golf carts. That remained the case for most subsequent races, once run every 3 years, before becoming biennial in 1999.

Things have changed in both departments. Sales of electric cars in 2015 and 2016 were far greater than all previous years combined, and 2017 has already exceeded this. Installed solar power almost doubled in the same amount of time.

Solar now powers tuk-tuks used for transport in congested Asian cities, but in Europe and America, if electric cars have solar panels they are usually to power the air-conditioning, rather than drive the car. At current efficiencies, covering a typical electric car in solar panels would extend its range by just a few extra kilometers, even on a sunny day. At the moment, if you want to power a conventional car with sunlight you’d have to charge the batteries using solar panels on the roof of your house.

That’s why the cars in the World Solar Challenge not only have surface areas shaped to catch sunlight but carry only the driver and at most one passenger. If mass-market cars are to be powered substantially by their own solar cells, these cells will need to be much more efficient than anything we have now, and the cars will need to get a lot lighter.

Tholstrup and the other challenge organizers hope that the machines now speeding down the middle of Australia will inspire designers to find better ways to bring solar-powered cars to the road.