If you happened to be passing through central Idaho in what’s now the Snake River plain some 15,000 years ago, you might have spotted entire fields of lava, covering more than 600 square miles. And if you swung back through the area this past week, you might have spotted an equally alien phenomenon: a little yellow vehicle, 16 feet long, covered in solar panels, and rolling at a stately 30 mph past the long cooled land that’s now called the Craters of the Moon National Monument and Preserve.

For the University of Michigan student stuffed inside the Novum, the Craters of the Moon would have been just one more point of passing interest. The real focus would have been on the Sun overhead—the only source of fuel and the key to taking first place in the 2018 edition of the American Solar Challenge—a 1,700-mile race from Omaha, Nebraska to Bend, Oregon.

For nearly 30 years, races like the American and World Solar Challenge have been proving cars can use solar panels to generate all the power they need. In the sky and on the sea, other pioneers are making a similar point: With the right sort of engineering, the Sun’s rays are all you need to go from point A to B.

As the world’s automakers finally get serious about building electric cars, the question arises: What are the odds they’ll be able to generate their own electricity from solar panels built into the roof, body, and glass, without sacrificing creature comforts like air conditioning, legroom, and the ability to keep up with highway traffic?

The upshot is tantalizing. Cars would be freed not just from their reliance on planet-killing fossil fuels, but from the need for a charging infrastructure whose slow growth remains a major pain point. But the odds, if you must know, are slim. Researchers are working on making solar panels lighter, nicer looking, and more efficient. The next generation of solar materials will be applied like paint, turning a whole vehicle (or just about anything else) into a solar panel. But even such advances are unlikely to make enough power for the average driver’s commute—cars will always have small surface areas compared with their heavy-duty power needs. The good news is that there are other ways to integrate solar power and transportation to make driving greener.

State of Charge

The silicon-based solar cells you see on roofs of houses today are an elegant piece of engineering, the result of a century of experimentation and refinement. They have no moving parts, and silently, continuously, generate electricity whenever it’s light out. But they’re not very efficient, converting just 15 to 20 percent of the energy that falls on them.

That hasn’t stopped automakers from trying to integrate them into vehicles. Henrik Fisker built a solar roof into his ill-fated Karma electric-hybrid, an early rival to Tesla. The company bringing the design back as the Karma Revero has updated the solar setup, and says it can now make 200 watts of electricity per hour. Too bad modern EVs need battery packs with at least 60 kilowatt-hours. Give the Revero eight hours of sunshine, and it can make enough power to drive a mile and a half.

That’s why Toyota bills the optional solar roof on the plug-in Prius Prime as a way to top up the car’s battery. (It doesn’t offer the setup in the US, saying American buyers haven’t shown much interest.) And when WIRED crunched the numbers to see if an EV with more surface area—Tesla’s semi-truck—we found it would take at least 80 hours to fully top up the batteries.

Power Boost

So not much is gonna happen today or tomorrow. But let’s look at where solar’s going. The next step for the tech is multijunction (sometimes referred to as III-V) solar panels, usually based on gallium instead of silicon, which offer much better efficiency—as much as 45 percent more. That means fewer panels on a smaller surface area can do the work, but at a higher cost. “If you want to send a rover to Mars, this is totally what you use,” says Joseph Berry, senior research scientist at the National Renewable Energy Laboratory. They’re also great for satellites, where weight is a more important consideration than cost for designers.

Indeed, while the Mars Curiosity rover got an onboard nuclear generator, its predecessors, Spirit and Opportunity, pootled around Mars on solar power alone. That’s why Opportunity, which has driven 28 miles on the planet since arriving 15 years ago, is currently in hibernation. It’s waiting out a dust storm that has blotted out the Sun and left it unable to charge.

That works for NASA, but back on Earth, car buyers are a little more sensitive to price and prefer to be able to drive on cloudy days. They can look to researchers working on a solar solution that could be not only more efficient, but also cheap: perovskite solar cells, made from low-cost and easy to handle materials. After about a decade of development, the tech is still in the lab but has real potential.

“The notion with the perovskites is we do have a path to 30 percent, but at a much, much, lower price point,” says Berry, who specializes in their development. Perovskite materials can be applied as a liquid, and painted on to surfaces, with metallic ink printed electrodes. “We can print this stuff like you print a newspaper.”

That could provide a new way to coat an entire car with solar generating material. But making the materials stable is still a challenge, according to Berry, and there are plenty of practical questions as well. What happens when a car with an electrically charged surface crashes? Would customers buy a car if they couldn’t choose the paint job? Could manufacturers integrate their application into the factory process?

Maybe then the answer isn’t to put the power generation on the cars themselves, with their limited surface area and hearty power demands. Perovskite materials give researchers the opportunity to cover not just vehicles, but also the garage they sit in, the house that’s attached to, and just about anything else you can think of, like street lights and factory roofs. “We talk about the notion of photovoltaics everywhere,” says Berry.

How about those miles and miles of blacktop on which cars drive? Idaho-based Solar Roadways is among those hoping to put some of that area to work making electricity, using heavy-duty solar panels that could self-defrost and contain lights for road markings. China claims to have opened the world’s first solar road in Jinan, at 1.25 miles long. The complexities may outweigh the advantages. The scale of solar roadways would help with the business case, but engineers have yet to figure out how to replace failed panels without disrupting traffic, or how to easily dig up the roads for pipe work underneath, for example.

With the advent of perovskite solar cells, large generation plants at the grid scale, with panels on factory roofs or in the middle of the desert, will become cheaper to build and operate, making it easier to supply everyone with green (yellow?) power. That’s where the bulk of Berry’s work is focused, and he believes a step change is coming. “That’s certainly what wakes me up in the morning,” he says.

So even if you leave the solar car to crafty college kids trundling across the country, you can be driving on sunshine.

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Geof Syphers got in his Chevy Volt Tuesday morning, like he does most days, and headed to the Sonoma Clean Power office in Santa Rosa.

Later that morning, he traveled south to the Lavio family farm in west Petaluma and drove to the back of the property where about 4,000 solar panels had been installed earlier this year. They were generating one megawatt of electricity, enough to power 300 homes.

One of those homes belongs to Syphers, a Cotati resident and the CEO of SCP. His electric car is charged solely by the sun’s energy, and it was the kind of commute Syphers is hoping will become a mainstay for residents throughout region.

“Building inside Sonoma County has been a goal from the beginning,” Syphers said. “This is the first (solar project) that we have finished. So one of the things that excites me is just being able to see this through, all the way from the plan through the construction and see it finally serving customers.”

This week, SCP and developer Coldwell Solar hosted a ribbon-cutting ceremony at one of the two solar power plants recently constructed in Petaluma, the first of their kind for the nonprofit electricity provider for Sonoma and Mendocino counties. The event was attended by local officials, Coldwell and SCP staff and members of the Lavio family.

Some two dozen rows of solar panels have been erected on undeveloped space behind the former dairy farm, quietly humming as they generate sustainable power along the lower slope of a hillside, completely hidden from nearby D Street.

The other plant is located in east Petaluma off Stage Gulch Road. Together, the two megawatts generated can power up to 600 homes by funneling the electricity through the PG&E grid to SCP customers using their EverGreen service, a premium package that comes from 100 percent renewable sources like these solar arrays.

SCP program specialist Nelson Lomeli said SCP currently has 1,643 EverGreen customers — 182 of them are in Petaluma.

“These projects will feed the electricity grid, so anybody in service would be able to take advantage of that electricity,” he said.

Uncovering project sites like these two are a rare occurrence in Sonoma County, Coldwell CEO Dave Hood said. Even with all the open space and clear skies, developers have to cut through all sorts of red tape — not to mention find locations that have the proper utilities set up so they can connect to the power grid without disturbing the land.

Coldwell has properties throughout the state, and Hood estimated they’re producing 1.2 gigawatts of solar power, which amounts to about 1,000 sites the size of the two plants in Petaluma.

Key to finalizing this project was SCP’s feed-in tariff program, or ProFIT, that allows landowners to lease their under-utilized space to generate utility- scale solar energy.

Once Coldwell located the two sites in Petaluma, it entered into a Power Purchase Agreement with SCP, selling the energy to the electricity nonprofit for the next 20 years. That means the Lavio family will be able to reap the benefit of that deal for two decades without having to ever lift a finger.

“I like to look at it this way,” Hood said. “Before the solar was there, that power was just going into the ground. Now we’re harnessing that.”

BERNARDSTON — A solar farm could be at 32 Fox Hill Road by the end of the year if the town’s approval process goes smoothly.

The land is owned by the Grover family, who run a dairy farm. They are leasing it to the Clean Energy Collective, a company based in Colorado with offices in Worcester that builds and manages community solar farms.

“We were trying to figure out how we could sustain the farm to be able to continue on for the next 105 years,” said Rena Grover. (The farm is now 105 years old.) “This was the most sustainable way to keep the farm going.”

Solar panels will cover about 23 acres of the 32-acre farm, said Chris Rodstrom, a co-owner of the Clean Energy Collective. As a community solar farm, residents and local businesses will be able to subscribe to the energy generated from the farm and its tax credits, “to essentially be shareholders in the solar energy,” Rodstrom said.

Rodstrom said that planners from the Clean Energy Collective have talked to the neighbors of the farmland and have adjusted their designs to accommodate nearby homes.

“We’ve been working pretty hard to try to present a plan that we think is a good balance for providing a lot of clean energy but also not impacting the town,” Rodstrom said. “I think it’s actually a pretty good fit for what we’re proposing and what the site can accommodate.”

On Tuesday the Conservation Commission opened its public hearing on the project, which it will resume August 7. The Planning Board will hold its public hearing August 2, although Chairwoman Chris Wysk said that the board probably won’t come to a decision then.

Rodstrom said construction of the solar farm will take “a few months.”