New solar cars defy sci-fi reputation

There are many ways to describe the solar-powered cars of today. A flying saucer with wheels. A teardrop with a cockpit. A drivable airplane wing. One word that never seems to come to mind is 'practical.'

A new generation of engineers is hoping to change that perception by introducing solar cars that nearly anyone could see themselves driving around town.

Dubbed 'cruisers' by those who design and build them, these vehicles look and function more like mid-sized sedans than flying saucers with wheels.

The cruisers will debut at this year's World Solar Challenge, a grueling 3,000-kilometre endurance race through the Australian outback from Darwin, on the north coast, to Adelaide, on the south coast.

The race is held every two years in early October and is widely regarded as the premier international showcase for solar-powered cars.

Canada's first cruiser

'Everybody thought we were crazy, showing up with a car we knew couldn't win. But soon, many other teams were saying "we'd love to build a car like this".' —Stefan Spychalski

The University of Calgary Solar Car Team, after three years of racing at the World Solar Challenge, has built Canada's first cruiser. Described as a "two-door coupe with a large rear-hatch," it is — by leaps and bounds — the team's most practical solar car yet.

"Our car has about twice as much storage as a standard Honda Civic," said Matthew Johnson, the mechanical engineering manager on the University of Calgary team. "You can put your golf bags in it, go for a picnic or pick up your groceries, which is a lot nicer than a typical solar car."

Johnson said he and his team were inspired to build a solar cruiser by the interest regular Canadians have in the potential of solar-powered vehicles.

"We take our cars to schools and community events across Alberta and the first question we would always get from people was, 'When will I be able to drive a solar car to work or around town?' " Johnson said. 

"In the past the answer would have been 'never.' I think we, and other teams from around the world, recognized the need for a practical solar car."

Street-legal solar

The ultimate end game for teams in the "cruiser class" is to build a car that can be street-legal in their home country.

The idea evolved from a surprise entry by the Bochum University of Applied Sciences in Germany in 2009. The team showed up with a solar car like nobody had ever seen before: bigger and slower, but just like the small cars that drive city streets throughout Germany.

It shocked the competition, but quickly other teams came around to the idea of building more practical solar cars.

"Everybody thought we were crazy, showing up with a car we knew couldn't win," said Stefan Spychalski, spokesperson for Bochum's solar car team. "But soon, many other teams were saying 'we'd love to build a car like this'."

Spychalski says cruisers will show the world that it's possible to at least imagine a family-style functional car powered by the Sun. He's quick to say that at the core, these cars are essentially the world's "most efficient electric cars that require little or no input from the electrical grid. We are taking the concept of an electric car to the next level."

A question of curves

But even the most ardent solar enthusiasts admit that the reality of solar car is, at best, decades off.

Solar cars use panels on their bodies to charge a set of onboard batteries that provide the power to the engine, lights and other systems.

Those batteries are heavy and take up space, and the design changes necessary to also accommodate passengers, trunk space and amenities like air conditioning make it very difficult to build a solar car that can harvest and store enough solar energy to run without help from the electrical grid.

The cruiser class cars at this year's World Solar Challenge are allowed to carry more batteries on board than their more traditional counterparts.

"In order to power a solar car, you need lots of surface area. To do that, you have to use an odd shape and design," said Marcelo da Luz, leader of the Power of One solar car project in Toronto and advocate for solar technology.

That odd design exposes a car's solar panels, or solar cells as engineers call them, to as much of the sun's energy as possible.

The best commercially available cells for use on solar cars are largely made from silicon and are able to convert about 20 per cent of the sun's rays into usable energy. That's not efficient enough to keep a moving vehicle's batteries charged without consistent sunshine, or provide enough back-up energy for nighttime drives unless the car is left idle in the sun during the day.

Helping hybrids with solar

On top of that, currently available battery technology is unable to store enough energy for trips exceeding a few hundred kilometres, giving drivers "range anxiety" and stifling public acceptance of electric vehicles in general, says da Luz.

Until commercial solar cells can convert more of the sun's rays into useable power, or batteries can store more energy per kilogram, the most likely option is to combine solar and electric technology in a single vehicle.

"What is practical is using solar as an augment to charge an electric car," said da Luz.

He points out that the Nissan Leaf, a fully electric car currently on the market, has a small solar panel on its rear spoiler. The panel is used to charge a battery that runs electrical components within the car.

Da Luz is hopeful that the cruiser class competition will encourage engineers to find a balance between practicality and efficiency, and integrate more solar panels on hybrid and electric vehicles.

"These cars are labs on wheels," said da Luz. "They represent an opportunity to test drive and innovate new technology."