Why aren’t there solar-powered cars?

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Chen Liu, Clarkson University

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Why aren’t there solar-powered cars? – Emma, age 16, Springville, Utah

Solar cars exist. The best place to see them is the World Solar Challenge, a race that’s held every two years in Australia. Competitors have to drive about 1,870 miles (3,000 kilometers), from Darwin on the country’s north coast to Adelaide on its south coast, using only energy from the Sun.

Many cars that compete in this race look more like amusement park rides or science fiction vehicles than the cars you see on the road. That tells you something about why solar cars aren’t an option for everyday travel, at least not yet.

Collecting enough sunlight

While a lot of sunlight falls on Earth during the day, the light becomes scattered as it travels through the atmosphere, so the amount that hits any given surface is fairly low. Averaged out over a full year to remove the effects of different seasons, it’s about 342 watts per square meter, an area equivalent to about 10 square feet. That’s...