Solar Cars Still in the Dark

Solar-powered cars may never be economically feasible, but the technology developed could still help reduce dependency on fossil fuels

On July 14 the students in University of Michigan's Solar Car Team unveiled the Continuum, a super-aerodynamic one-man racer that sports a shimmering armor of solar panels. The Continuum, UofM's ninth solar racer in 18 years, is a top contender in this October's Panasonic World Solar Challenge—a roughly 1,900-mile race from the northern to southern border of Australia. Compared with previous generations, this car looks less like something out of The Jetsons and more like something the average consumer might one day drive to work.

That's because Events South Australia, the division of the country's tourism commission that organizes the race, this year imposed new rules to encourage more practical, commercially feasible, sustainable vehicles. UofM and its competitors, 46 other corporate-sponsored universities and research labs, now must use some 25% fewer solar cells than years before, drivers must sit at a slightly more upright, 26-degree angle, and all cars must observe the country's 110 km/h speed limit (about 68 mph).

The Solar Race is On

While a production solar-powered car is still more an object of science-fiction wonder than a near-term reality, in recent years several solar-powered boats have hit the market (see, 5/17/07, "New Light on Solar Energy"). Now staging its 20th biannual race, the World Solar Challenge has emerged in both renewable energy and automotive industries as the central catalyst of worldwide innovation aimed at this elusive goal. The North American Solar Challenge, another biannual race formerly sponsored by the U.S. Energy Dept., is chiefly an academic competition.

"The solar car competitions do drive technology forward, but in a more exploratory way rather than directly applicable technology to mass-produced automotive applications," says Dean Degazio, development engineer for hybrid vehicle integration at General Motors (GM). For years, GM has played a major role in the UofM team's cadre of backers, a list that also includes Ford (F), Netherlands-based diversified resources company BHP Billiton (BBL), and Michigan-based automotive technology maker Denso. "Advances in structures, power management, solar cell output, and ingenuity of design for low drag, low rolling resistance," says Degazio, make solar cars "very compelling projects in the context of an engineering curriculum."

The mass market certainly couldn't afford a car like the Continuum. Whereas in 1989, the team's first year of development, donations of cash and materials totaled less than $500,000, in 2005 they came to $1.8 million. For 2007's Continuum, the team raised upward of $2 million. For the first time, GM supplied the molds for the Continuum—a tax write-off of about $50,000. Ford will be supplying a wind tunnel model and will help train the team's drivers.

Costly Cells

By far the most expensive component of the Continuum is its high-efficiency photovoltaic solar cells, the silicon-based panels that convert the sun's rays into electricity. UofM spends about $500,000 on the high-end cells, which are made only by a handful of companies, such as Albuquerque (N.M.)-based Emcore (EMKR), and Sylmar (Calif.)-based Spectrolab, a subsidiary of Boeing (BA).

As opposed to the simpler photovoltaic cells you might find on the roof of a house or on a solar-powered calculator, which make use of about 15% of the energy available in sunlight, these "multi-junction" cells are about 27% efficient and cost about 100 times more.

The photovoltaic industry, initially fueled by space applications (such as powering communications satellites), has seen rapid growth in recent years because of an increase in demand for renewable energies in the commercial marketplace. According to Paul Maycock, industry consultant and president of Williamsburg (Va.)-based Photovoltaic Energy Systems, the sector has seen 40% compounded growth over the past seven years to reach around $15 billion in 2006. Currently about 15% of that market is in consumer products, such as grid-connected rooftop panels. It may grow by as much as 40% compounded over the next 20 years.

Solar cell makers see autos as a possibility but aren't factoring them into their projections for the foreseeable future. "We're always looking at new markets," says David Danzilio, general manager of Emcore's photovoltaic division. "Nobody from the automotive industry has approached us. Our products will be quite suitable to that application when the time comes."

Others are more skeptical. "I don't think there will ever be [a production solar-powered car] that's very feasible," says Tom Carroll, a recent graduate of UofM and the current business director for its Solar Car Team. "If you look at our car, the weight is around 600 pounds, it generates about two horsepower, and it has one driver who's not exactly the most comfortable."

Unplug and Go

And perhaps advances toward plug-in electric cars and residential solar panels will supplant the need for a solar-powered car altogether. Imagine, for example, a world where every garage has a roof lined with solar panels, and everyone plugs their car in when they get home. When they get to work, they plug their car into the solar chargers in the company parking lot. If these advances come to fruition, why cart around expensive solar panels all day and deal with their slower speeds and shorter range?

In January of next year, French sports carmaker Automobiles Venturi will be the first company to launch a production hybrid solar-electric car. The Astrolab is a light, two-person car with 21% efficient solar cells. It can go up to about 75 mph and has a range of 68 miles. While a surprising pioneer, the Astrolab shows the limitations of solar power. It will cost around $125,000—the cost of a high-end sports car or ultra-luxury sedan—but looks more like a go-kart than a car.

Click here to see the latest in solar-powered vehicles.

Before it's here, it's on the Bloomberg Terminal.