The closest most people can get to a solar-powered car is to buy a battery-electric vehicle and charge it with electricity generated by a home solar array.
But cars powered directly by the sun really do exist--at least a handful of them.
Every two years, teams from around the world converge on Australia to compete in the World Solar Challenge--an efficiency competition for purpose-built solar cars.
The 2015 World Solar Challenge wrapped up October 25, after 40 teams from 20 countries covered around 3,000 kilometers (1,864 miles) on solar power.
The route stretched from Darwin in the extreme north of Australia, to Adelaide on its southern coast.
As in long-distance rallies, cars are shadowed by support crews, but the teams themselves must be essentially self sufficient.
2015 World Solar Challenge
Drivers were tasked with covering as much distance as they could on each day until 5:00 p.m. local time, when they stopped and made camp wherever they happened to be.
Cars are only allotted 5 kilowatt-hours of onboard energy storage--anything else needed to propel them must be continuously harvested from solar panels.
All cars are purpose built for solar racing, and are divided into the three classes.
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The Challenger Class consists of streamlined single-seaters, built to maximize aerodynamic efficiency and the placement of solar cells.
This year marked a one-two finish for The Netherlands, with the Dutch Nuon Solar Team and Solar Team Twente taking first and second place, respectively.
The winning Nuon car completed arrived in Adelaide 37 hours and 56 minutes after leaving Darwin, and averaged 91.7 kph (56.9 mph).
The Cruiser Class was introduced in 2013 in an attempt to bridge the gap between the alien-looking Challenger Class cars and everyday production models.
2015 World Solar Challenge
While they look nothing like the average sedan or hatchback, these cars do have four seats and a trunk.
Cruiser Class entries may recharge from the grid at certain points, and are also judged on design features such as ease of access, comfort, and "desirability."
The 2015 Cruiser Class winner was another Dutch entry--the Stella Lux of Solar Team Eindhoven.
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Finally, the Adventure Class is open to vehicles that competed in previous years, or that do not meet the technical regulations for the other two classes.
The top finished in this class was Australia's own TAFE SA team.
The next World Solar Challenge will take place in 2017, giving engineers another chance to demonstrate what solar technology can do.
[hat tip: Brian Henderson]