Toyota Motor is trying to figure out how to make a car run forever

Put together the best solar panels money can buy, super-efficient batteries and decades of car-making know-how and, theoretically, a vehicle might run forever.

That’s the audacious motivation behind a project by Toyota Motor, Sharp and New Energy and Industrial Technology Development Organisation of Japan, or NEDO, to test a Prius that could revolutionise transportation. “The solar car’s advantage is that — while it can’t drive for a long range — it’s really independent of charging facilities,” said Koji Makino, a Toyota project manager.

Even if fully electric cars overtake petroleum-powered cars in sales, they still need to be plugged in, which means building a network of charging stations across the globe. The sun, on the other hand, shines everywhere for free, and when that energy is paired with enough battery capacity to propel vehicles at night, solar-powered cars could leapfrog all the new-energy tech being developed, from plug-in hybrids to hydrogen fuel-cell vehicles, in one fell swoop.

But the current forecast is only partly sunny because there’s still some work left to reach that level of efficiency. “This is not a tech we are going to see widely used in the next decades,” said Takeshi Miyao, an auto analyst at Carnorama. “It’s going to take a long time.”

Not for lack of trying. Toyota and Hyundai Motor already introduced commercial models with solar panels on the roof, but they were too underpowered and could barely juice the sound system.

A Prius plug-in hybrid that sells for more than 3 million yen offers solar panels as an option, but they only charge the battery when parked. The maximum amount of power for driving only lasts about 6 kilometers, said Mitsuhiro Yamazaki, director at the solar energy systems division of NEDO.

Toyota has been testing a new solar-powered Prius since July, though it acknowledges that cars running nonstop without connecting to a hose or plug are still far away. Even so, the Toyota City-based firm said the research will pay off in other ways. Indeed, there have been some breakthroughs, mainly due to advancements by Sharp. The prototype’s solar panel converts sunlight at an efficiency level of more than 34 per cent, compared with about 20 per cent for current panels.

Because the solar cell being used by Toyota, Sharp and NEDO is only about 0.03 mm thick, it can be placed on more surfaces, including the curvy parts of the roof, hood and hatchback. The electrical system can charge the vehicle even when it’s on the move. If the car is driven four days a week for a maximum of 50 kms a day, there’s no need to plug into an outlet, NEDO’s Yamazaki said.

Toyota’s bet on solar is one of many that Japan’s No.1 carmaker is placing on the future of transportation. With Volkswagen and other auto titans facing uncertain futures as new technologies and business models ripple through the $2.23 trillion global industry, they’re investing billions of dollars in cars powered by electricity and hydrogen to keep apace.