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Tina Casey headshot

The Ultimate Green Car: Built-In Solar Panels To Power Electric Vehicles

By Tina Casey

Businesses that use electric vehicles get good marks for helping to fight air pollution, and now, auto manufacturers may be on the verge of giving them an even better opportunity to flash their green cred. At least two startups are planning to offer EVs that generate their own electricity on the go from built-in solar panels, and more may be on the way.

Solar panels on trucks are already a thing, but they are generally meant as an add-on, providing an auxiliary source of electricity for lifts, lighting, air conditioning and other accessories. This new crop of solar powered passenger cars takes it up to the next level by providing motive power.

An electric vehicle with built-in solar panels

Not too long ago, electric vehicles with built-in solar panels would have been a pipe dream: too expensive, too heavy, and too inefficient to be practical.

Well, that was then. Solar panels are now lighter, less expensive and more efficient, and Sono Motors is one startup jumping on that opportunity.

The built-in solar angle also benefits from advances in the new lightweight materials used in auto manufacturing. Lighter autos mean that EV batteries can provide longer range. Here's the rundown on Sono's "Sion" model:

The full efficiency of the Sion is guaranteed by the lightweight design. The exterior is mainly made up of rust-proof polycarbonate [a type of plastic resin]. It further is scratch-resistant. The most unique feature in the body work are the solar cells, which are located on the roof, on both sides as on the hood and the rear.

The Sion will have 330 integrated solar cells in all. Wear and tear would be a major consideration, but Sono states that the polycarbonate shell provides a shatterproof, weather resistant cover.

According to Sono, when weather conditions are right the solar panels alone can provide the car with a range of 30 kilometers, or a hair over 18 miles.

The battery can also be charged from an outside source for a range of 250 kilometers. That's important because in less than optimal weather—in winter, for example—the solar panels may only cover as little as three miles of travel.

Even at three miles, that's quite an improvement over another recent iteration of built-in solar panels. Last year, Panasonic announced a rooftop solar system for sedans, but it's more on the order of an efficiency booster than a means of making the car go.

An auto mechanic in every garage

The Sono battery is designed to be bidirectional, meaning it can be used to power any common household electronic device. That could provide some interesting opportunities for local businesses at street fairs and other community events.

Another point of interest is that Sono offers a lease option for the battery. Batteries account for a major portion of the cost of an electric vehicle, so the battery lease would help reduce the up-front cost of the car.

What really makes the Sono business model interesting, though, is the repair plan.

An electric vehicle power train is relatively simple compared to conventional engines, and Sono has taken advantage of that benefit to design a car that can be repaired by novices -- at least, in theory.

To be sure, you would have to be handy to begin with, but according to the company you can order most spare parts online and follow step-by-step tutorials:

With the help of our step-by-step manuals, everybody should be able to repair the Sion, single-handed and for free. We will offer the instructions as videos and texts. If you do not feel like repairing the Sion by yourself, just bring it to the next auto shop. Since we will unveil the complete workshop manual, every mechanic in the world should be able to repair the Sion.

Solar panels on cars: everything old is new again

The next couple of years could be a breakout season for solar panels on electric vehicles, and it has been a long time coming.

Mazda is acknowledged to be the first to attempt it back in 1992, but the results were disappointing: too expensive, and not very effective.

By 2009, Toyota, Audi and the now-defunct startup Fisker Automotive were on board with the concept.

However, MIT Technology Review took a good look at the on-board electricity generation angle back in 2008 and threw some cold water on the subject. High costs were among the obstacles cited by MIT article:

“I think it’s more a marketing gimmick,” says Andrew Frank, a plug-in hybrid pioneer at the University of California, Davis, and chief technology officer for UC-Davis hybrid-vehicle spinoff Efficient Drivetrains. “It takes kilowatts to really drive the car.”

MIT also noted that the small surface area, sub-optimal angle and lack of a sun-tracking feature make car bodies less than ideal places to put solar panels. Researchers modeled out a car with the most powerful solar cells available on the market, and the results were still disappointing.

The conclusion was that it made more sense to put more money into improving battery range and simply charge electric vehicle batteries by plugging into stationary solar panels, rather than adding solar panels to cars.

On the other hand, the article included this parting observation:

Frank says that, even if onboard solar is a marketing gimmick, it could advance the electrification of transportation by advertising the possibility of replacing gasoline with renewable energy. “Whether it’s perception or real doesn’t matter,” he says, “because it creates public awareness.”

Solving the EV charging conundrum

That certainly was a prescient observation. Rooftop solar panels are generally hidden from view, but putting them on cars and trucks bring them down to eye level.

Companies like Ford have already noticed that the high visibility of small wind turbines can have branding value, and the same could be said of vehicles that are literally solar powered.

Solar cells are more efficient, energy storage technology has also improved, and innovation in both areas is ongoing, leading to future drops in weight and cost. EV electrical system integration is another area in which efficiency has improved. All together, this has created the opportunity for solar-integrated electric vehicles to leap from failed concept to a functioning reality.

Sono plans to start production in 2019, and the Dutch startup Lightyear is also taking orders for its solar-integrated EV, so it seems that companies looking for trendsetting clean power branding opportunities will have some new alternatives in the coming years.

Image: via Sono Motors.

Tina Casey headshot

Tina writes frequently for TriplePundit and other websites, with a focus on military, government and corporate sustainability, clean tech research and emerging energy technologies. She is a former Deputy Director of Public Affairs of the New York City Department of Environmental Protection, and author of books and articles on recycling and other conservation themes.

Read more stories by Tina Casey