Japanese High Technologies Put Together
Tokai Challenger is about 5 meters long, 1.6 meters wide and 1 meter high, and weighs 134 kg or a 10th that of an ordinary compact car. The vehicle is a single-seat tricycle, powered by a rear–wheel drive system. The vehicle does not really look like any of the cars you know; it looks more like a huge board because it has a large solar panel set on the roof to receive as much sunlight as possible.
A view of the vehicle's cockpit. |
The narrow cockpit can barely seats a driver. |
Why is it that Japanese solar cars are so fast? According to Professor Hideki Kimura of Tokai University, a leading solar vehicle researcher in Japan and a leader of the university’s solar car team, the solar model “is the essence of Japanese technology." Japan is known for its great manufacturing technologies, all of which are put together to produce the solar vehicle.
The vehicle's body has Japanese-made solar panels boasting the world’s highest sunlight-to-electricity conversion rate.
Until 2010, solar cars used to have solar panels made of compound semiconductor solar cells, an advanced type of solar cell used for spaceships and other sophisticated systems, rated at 30% in sunlight-to-energy conversion. From 2011 on, however, race organizers introduced a stricter rule of competition, making it mandatory to use easily available solar cells. So, Tokai University has been using silicon solar cells often used for home solar panels. Silicon solar cells are for general use and still durable. This all-purpose type of solar cell has a lower energy conversion rate of 22% at best, but it is still one of the best silicon solar cells in the world.
The solar vehicle's motor was also made in Japan. (Photo courtesy of Tokai University)
The solar car is powered by a very efficient electric motor. The motor can use as much as 97% of all electricity generated by sunlight to power the vehicle, and only 3% of electricity is wasted. It is a world-class level of efficiency.
The body of the vehicle is made of a high-tech material called carbon fiber, which Japan is very good at making. Carbon fiber is made of carbon and little else, so it is lightweight and tough. Carbon fiber is widely used for important parts such as the body, main wings and tail wings of spaceships and airplanes as well as for sporting gear such as tennis rackets. Japan is the world's number one carbon fiber-producing country and its quality is also rated the best in the world. The solar vehicle made from lightweight, strong carbon fiber has also been made very light.
The solar car's lithium ion batteries can store a large amount of electricity and yet are lightweight. A total 450 batteries are connected to one another – 15 batteries in parallel and 30 batteries in series – to store enough electricity for 3 hours 45 minutes of solar battery output. The battery is covered with a thin film, instead of paint, to reduce weight. Solar cars can thus be called a collection of cutting-edge technologies.
The car body is made of Japanese carbon fiber, a lightweight and tough material used in airplanes and many other products. (Photo courtesy of Tokai University) |
Lithium ion batteries, widely used for laptops and other high-tech products, are lightweight, safe and capable of storing a large amount of electricity. (Photo courtesy of Tokai University) |
Weather Satellite Used in Racing
Tokai Challenger's strength goes well beyond the vehicle itself. The Japanese weather satellite Himawari was in orbit watching weather over a wide area, including Australia where the car race was held. The solar car's crew was able to see Australian weather in highly precise satellite images. They also knew, beforehand, about the amount of clouds and, therefore, sunlight waiting for the solar vehicle by analyzing images captured with five different satellite sensors such as visible light and infrared.
There were cases where the sky was cloudy but the driver knew from the weather satellite that there was a sunny break ahead and accelerated to get there fast. In other situations, the driver knew it would be cloudy all day and would continue to drive at a lower speed.
Tokai University's team members in the South African race included Saudi Arabian students studying solar energy as well as two women, including one of the drivers. She finished in first place, the first time for a female driver. The Tokai University team, supported by Japan's high technologies as well as students' teamwork, plans to develop a four-wheel solar car with improved usability in 2013.
Members involved in the Light Power Project at the Tokai University Challenge Center. (Photo courtesy of Tokai University)
In Japan, electric cars are quickly becoming a common sight, while solar vehicles may take a little more time before they are widely used. What is necessary for the development of solar cars now is to gather as much knowledge as possible from races such as the solar car race and feed it back to the development side. At the end of the road will be waiting commercially viable solar cars that will help us sustain the earth's environment.
(January 2013)