Wish We Were Here ...
Solar power has long been the awkward cousin of the other green technologies touted as alternatives to the internal combustion engine. On the one hand, it has huge potential – the energy in just one hour of sunlight hitting the earth could power the world economy for an entire year; but on the other, no one has quite worked out how to harness this energy to power cars. Slowly, however, the gap between possibility and reality is being closed in innovative ways.
The achievements of Louis Palmer, a self-styled environmental adventurer, illustrate the size of the challenge. In 2008, Mr. Palmer became the first person to circumnavigate the globe in a car powered solely by the sun. The vehicle's battery stored the sun's energy and allowed him to travel at night and so cover distances of up to 100 kilometers in 24 hours. His pioneering adventure proved beyond doubt that solar energy can be a legitimate alternative to petrol or diesel.
However, it also highlighted the many reasons why solar power is hugely impractical for everyday use. Mr. Palmer's vehicle, the Solartaxi, only has room for two people and it needs to drag around six square meters of photovoltaic cells on a five meter long trailer to generate sufficient power. This is hardly practical for a trip to the local store.
Solar power's drawbacks do not end there. The photovoltaic cells typically used to power cars are bulky, expensive to manufacture and do not provide anywhere near enough power needed to drive a traditional five door family car. The range of most solar powered cars is also severely limited, particularly in countries where the sun does not shine frequently. In the words of one solar expert: "We can't all live in California".
Even the most passionate supporters of solar power accept that it is a long way from being a practical alternative to fossil fuels for cars. Mr. Palmer – speaking from the Ural mountains, where he is organizing and taking part in the world's first zero-emission round-the-world race – describes solar-powered cars as "an eighties concept" and points out that the vehicles he drives tend to be lightweight prototypes that are expensive to build.
It seems the world's car manufacturers have reached the same conclusion. They have produced solar-powered cars – such as BMW's Lovos car or the Honda Dream – but these are usually just concept cars or made to run in specialist races. John Kingston, government affairs and environment manager for Honda in the UK, says that despite the Honda Dream winning the prestigious World Solar Challenge race in 1993 and 1996, the technology wasn't developed further. "We reached the conclusion that solar was not the most effective way to power a car," he says.
Ken Zweibel, director of the Solar Institute at the George Washington University, says solar cars are often just used as a publicity stunt by the big car makers. "You might as well just use a plug and batteries," he says. "There are uses for solar panels on cars, such as keeping batteries charged or cooling, but you only get three-quarters of a kilowatt hour per day from a square meter of solar panels, which equates to a couple of miles. No car has 10 square meters to devote to solar panels."
Not everybody, however, takes the view that solar panels have no place on the cars of the future. Hannah Macmurray, a former car designer for Honda and Mercedes Benz and now editor of Green Car Design magazine in London, says: "If we're saying that [solar] is a waste of time, then we're saying that things like fuel cells are a waste of time. If we don't start somewhere, we won't get anywhere."
Research into solar cells is also moving on. Swiss-born inventor and physicist, Nunzio La Vecchia, advocates a "solar skin" that gets around the problem of bulky panels. His company, NLV Solar, worked in partnership with Swedish supercar manufacturer Koenigsegg to develop the NLV Quant car.
It is powered by two electric motors on the rear wheels and is covered in a photovoltaic solar skin, which sends the sun's energy to a lightweight battery in the car. Ultimately, the NLV Quant relies on most of its power from other means, and the high-tech solar skin only powers its cooling system.
But Mr. La Vecchia's car illustrates the advances being made in the field. This is why the world's biggest car manufacturers, despite the current drawbacks of solar power, are not abandoning the concept altogether. Some are finding there is a third way: To use solar as a supplement to both petrol and electric power. The hybrid car of today is rapidly evolving into the tribrid car of tomorrow. The 2010 Toyota Prius hybrid can be fitted with a solar roof for an extra $10,000, Nissan's new Leaf hybrid car can be fitted with a solar panel spoiler and General Motors will introduce a solar option on its Chevrolet Volt hybrid car.
Outside the mainstream car makers, French battery manufacturer Bolloré and Italian car designer Pininfarina teamed up in 2009 to create the 'Bluecar' – a hybrid of electric and solar – and for the true renewable disciple there is the Venturi autonomous energy vehicle that runs purely on wind and solar power.
Solar Electrical Systems in California designed the solar roof on the Toyota Prius. Greg Johanson, the company's chief executive, says there is increased demand from carmakers for his company's expertise. But he is also realistic about the potential of the technology.
"Solar panels are better on a Soccer Mum's SUV than on a Prius. Solar will give you two miles but batteries will give you 30 miles," he says.
Ultimately, the role of the solar panel in powering cars might well lie, not on the car itself, but on the garage that houses it. Ms. Macmurray says: "Keep in mind that solar panels are a product designed for commercial use on flat objects that don't move – from calculators to buildings. Car designers, and probably not engineers, were the ones who put them on cars."
Mr. Palmer is adamant that this is the future for solar-powered cars: "Today we have batteries that allow you to charge the car from home. If you put 10 square meters of solar panels on your roof you can generate 15,000 miles of driving time. For a cost of between €4,000 to €5,000 you won't need to visit a petrol station for 40 years," he says.
"The world has so much roof space. If everyone put solar panels on their roofs, we could be independent of fossil fuels."
Mr. Corbett is the reports editor for The Wall Street Journal Europe. He can be reached at charlie.corbett@wsj.com
