Is a Solar-Powered Car Coming Soon?

Last Updated Aug 2, 2011 11:04 AM EDT

Sunlogics is installing this solar canopy at Volt dealerships.
GM Ventures, the venture capital arm of General Motors, recently announced a $7.5 million investment in Michigan-based Sunlogics, which makes solar-powered electric car changing stations. GM also revealed it was committing to doubling solar capacity at its plants to 60 megawatts. Large solar arrays atop flat-roofed GM plants can dramatically cut the company's carbon emissions and help it walk the talk on alternative energy. But is solar headed for a really big role powering cars? Nah.

GM--and every other automaker--is a still world's away from a "solar car" that could actually run on electricity from its own small photovoltaic panel. There's a lot of public confusion about that as automakers boast about the solar they're adding to cars, but vehicles running solely on photovoltaics are not happening now, or maybe, ever.

The limits of solar
An increasing number of cars actually do have small roof- or spoiler-mounted solar panels, but they're mostly a feel-good exercise. Even the phrase "solar cars" is misleading because it is impossible to run any kind of practical car from its own solar panel. You have to strip a car to its absolute fundamentals -- a frame, a seat, wheels, an electric motor -- just to get something that will roll and compete in a solar race.

Electric cars are energy hogs, and it takes a significantly large battery pack to give them even a 100-mile range. Auto roofs don't have much space for a solar panel, so one that's sized to fit on a regular car will provide only a minuscule amount of power, and not nearly enough to drive the car.

So a car-mounted solar panel is maybe good for powering the CD player, or -- as in the case of an option on the Toyota Prius -- providing some useful air circulation while the car is parked. The forthcoming Fisker Karma will also have a solar panel on the options list, which makes sense because it has a lot of gaudy green tech (including dash wood recovered from river bottoms).

But who can deny the showroom appeal of auto-mounted solar for green consumers? The panels can be mounted on the top of the car or even incorporated as thin photovoltaic film into the fabric of a convertible top? Actually that last one is fanciful but it got a lot of mileage when it was announced as part of a "Volt convertible" April Fool's joke.

Some automakers have made some form of solar assistance an option, and discovered to their amazement that consumers really like it. Some 95 percent of people ordering the Nissan Leaf electric car are opting for the upscale SL model, and two main reasons are the availability of a fast-charging port and the really cool spoiler-mounted solar panel. It's a great talking point, but all it does is charge the 12-volt accessory battery. As Mike Boxwell points out on a Leaf forum:

It's a really tiny panel. And it is amorphous, which means it is pretty inefficient (but cheap). At a guess, the solar panel can generate a peak of around five to six watts, which would work to trickle charge your mobile phone or satellite navigation system, but probably no more than that.
A history...on concept cars
"Solar cars" actually have a long history. The first entries were home-built cars like the "Bluebird" and "Quiet Achiever" in the 1970s, but then Ford installed headlight-mounted solar in the 2006 Reflex concept car, and around the same time Mazda put a rooftop panel in the similarly fanciful Senku. The Cadillac Provoq powered accessories from solar. The French company Venturi has tried to market a three-passenger car called the Eclectic that gets power from wind, batteries and solar. Too bad it can only go 30 miles an hour.

Hope springs eternal, I guess. Solar costs are coming down rapidly, while output climbs. Maybe someday we will actually ride around in solar cars. But that day isn't around the corner, and it's probably not on the imminent timeline, either.

Under the canopy
Solar is actually very useful when it's integrated into electric vehicle charging. Sunlogic is putting solar canopies (which hold the panels and double as car ports) at Chevrolet dealerships selling the Volt. GM has two Sunlogics solar canopies installed so far, and wants to have 250 signed on. The canopies deliver about 25 percent of the dealerships' electric needs. That's a smart use for solar (GE is building similar chargers) because stationary panels can be scaled to actually deliver useful power.

It makes sense that the GM Ventures fund, launched last year with $100 million to spend, would put money into this kind of solar. Its other investments are also in not-quite-there-yet-for-the-car technologies (including solid-state EV batteries) that showcase its forward thinking. GM's smartest money went into Bright Automotive, which builds a very smart plug-in hybrid panel truck that had been starved for development capital.

I listen when GM Ventures' Jon Lauckner talks, because although Bob Lutz gets all the credit for the Chevy Volt, it's actually Lauckner who sketched out a practical car. His thoughts:

Global solar energy use is predicted to more than double by 2016, so we believe that investing in renewable energy is a smart and strategic business decision.
That's undeniable, but solar will ultimately prove its worth on the utility scale -- with really big applications covering hundreds or thousands of acres (some using mirrors to "concentrate" the sun's rays) and replacing coal and other fossil fuel plants. Solar needs a lot of room to work well, and a car's roof is just too small.


Photo: GM