Solar-powered cars use photovoltaic solar cells to convert the sun’s energy into electricity. While most solar cars are still in the experimental phase, the Toyota Prius is a street-legal car that harnesses the sun’s energy to power its air-conditioning system. Fully solar cars can be seen in action every year at the World Solar Challenge and the North American Solar Challenge, two road races widely attended by solar enthusiasts.
How Solar Power Works
Solar cells absorb the sun’s light and convert it into electrical power. Each cell is a tiny rectangle cut from a thin sheet of silicon or other semiconductor. The cells are arranged together in frames, creating a larger solar panel. When sunlight hits the panel, the silicon absorbs the sun’s rays, packaged in invisible particles called photons. The photons sink through the silicon, loosening the material’s electrons. The electrons float on the surface of the silicon while the photons stay on the bottom. The negative electrical charge on the top of the panel and the positive charge on the bottom function like a battery — when these charged terminals are connected with a wire, they produce electricity.
The First Solar Car
An Australian named Hans Tholstrup drove the first solar car in 1982, according to the U.S. Department of Energy. Named the “Quiet Achiever,” it drove 2,800 miles in 20 days—beating a gas-powered car. Tholstrup founded the World Solar Challenge race to foster the growth of solar science and solar car experimentation.
Production Cars with Solar Elements
Although no commercial car has ever been offered with complete solar power, several have had solar components. The 2010 Toyota Prius, with optional solar-paneled roof, is the most famous. Audi’s A8 also has an option for a solar panel and the Mazda 929 offered the option as long ago as the 1990s, according to CNN.
Solar Car Challenges
Why don’t we have more entirely solar powered cars? Les Jackson of the “Washington Times” says it’s because of the solar panel surface area required to run a car. According to his calculations, one unit of horsepower requires 7.43 square feet of solar cells. To generate 50 horsepower, a car that is 19 feet long would be needed. What’s worse, these estimates don’t take into account the solar panels’ poor energy conversion, which is only 20 percent of the absorbed energy converted into power.
The Power of One
One recent solar success story is “The Power of One.” Built by former flight attendant Marcelo da Luz, this solar car made a highly publicized trip from Canada to the U.S. in 2009. It's 16 feet long and 6 feet wide, forcing da Luz to drive while lying down, not unlike a luge or skeleton sled. The car’s top speed is 75 mph, generated by almost 900 mono-crystalline solar cells with power stored in lithium ion batteries. When the battery is fully charged, the car can travel 300 miles in sunlight and 130 miles in the dark.