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Racing With The Sun

How would you like to cruise right past the gas station in your solar-powered car? No need to stop to buy fuel—your new car runs on free sunlight. Sounds pretty cool—and it’s not just a daydream.

Students at the University of Kentucky achieved major success this summer with their version of a completely solar-powered car.

Despite problems with overcast skies and strong headwinds during segments of the 2008 North American Solar Challenge car race, UK’s Gato del Sol III solar car rolled across the finish line of a 2,400-mile race that began July 13 in Plano, Texas, and ended in Calgary, Alberta.

Trials and errors
In his blog from Canada on the afternoon of July 22, driver Mark Taylor posted a cheerful message to all the folks back home and around the world who were following the team’s progress online. “We got 11th!” Mark wrote. “We are just happy to be a part of Kentucky’s first solar car that qualified and finished.”

Building a solar car isn’t that hard—if you only want a toy. Miniature versions of solar-powered cars have been around for many years.

Some come out of the box already assembled and others are do-it-yourself kits. These little cars are great fun to watch zip across the kitchen floor. Priced between $10 and $20, they’re an affordable gift for the boys and girls on your Christmas list this year.

Designing and building an adult-sized, road-ready solar-powered car is a lot more complicated.

UK students first began tinkering with a full-size, all-solar car in 1999. By 2003, they had a car capable of traveling at a top speed of 40 miles per hour, and entered their Gato del Sol car in that year’s American Solar Challenge race. Although the car didn’t qualify for on-the-road racing, the UK team did win the Sportsmanship Award for loaning their $15,000 motor to a team from the University of California, Berkeley, so their vehicle Solar Bear could continue racing.

Their second attempt at building a workable solar car began in the fall of 2003, with 25 students working on the project. Engineering student Nick Such got involved in the effort in April 2005 at the end of his freshman year.

Nick recalls the push to get the car ready for that year’s July race, which had been renamed the North American Solar Challenge, a truly cross-country event with a course running through both the United States and Canada. “I worked on minor finishing touches, things like helping to waterproof the car, and making sure we met all the regulations.”

Nick recalls with a laugh, “Height didn’t work out for me as far as basketball goes—I’m 5′ 8″. But being short helped me to become one of the drivers that year even though I was only a freshman.”

Each car entered in the race had to meet exacting standards on paper, then prove its road-readiness during qualifying rounds. The UK team took their car out to the starting point in Austin, Texas, in an enclosed trailer. They brought the car out into the sunshine to begin “fueling” their entry amid the other contestants. The week before the race included evaluations and dynamic testing of each vehicle—and that’s where UK’s second attempt ran into trouble.

Nick says, “In 2005, we passed all the inspection parts. Then, about two-thirds of the way through the qualifying laps on the track, we started having electrical system issues. At about mile 80 of the 120-mile qualifying test, the electrical system shut down.”

UK’s Gato del Sol II was forced to drop out of the competition.

“One of the key things we learned that year was that you need adequate time to test your car before going out to the race,” Nick says.

Planning and paying for a long-distance car race featuring innovative technology isn’t easy. When UK’s 2005 team returned to Lexington, no one was certain when the next race would take place. The students continued to analyze every inch of their failed car, working to figure out ways to correct problems. Modifications and corrections continued at a slow pace, but without a new race scheduled, the work didn’t seem urgent.

Third time’s the charm
Then in October 2007, details for a new race to be held in July 2008 were announced.

With sponsorship support from Defond North America (an electronics manufacturer), Toyota, and Missouri’s Crowder College, the 2008 North American Solar Challenge would focus attention on “a greater understanding of solar energy technology, its environmental benefits, and its promise for the future.”

A rule change for the 2008 race requiring the driver to sit upright instead of reclining meant some serious rethinking would be needed. With less than 10 months to get their entry ready, the UK team chose not to start from scratch.

Instead, they decided to modify the basic design of Gato del Sol II. The new entry, Gato del Sol III, would feature a completely new aluminum chassis, but the existing shell would be modified. They’d also reuse some of the older parts, including many of the internal electronics components and exterior solar cells.

Working with a penny-pinching budget of only $85,000, financing for Gato del Sol III was a creative combination of support from seven major donors and small contributions from individuals. Students volunteer their time to do all the labor involved in putting the car together. The car is garaged in the Terrel Civil Engineering building on UK’s Lexington campus.

Mechanical engineering student Kevin Wieman, who did some of the welding work on Gato del Sol III, notes that each car is very much a team effort.

“We meet at the garage on Monday nights and Saturday afternoons,” Kevin says. “Since we finished the race last year, our team has grown to include 40 to 50 students.” Only one woman participated during the 2007-2008 academic year, but now 10 women are involved in this newest car project.

The budgets for the top three finishers in the 2008 race varied from $2.4 million (first place, University of Michigan) to $200,000 (second place, Principia College), to $1.5 million (third place, German entry from FH Bochum).

Work on UK’s new solar car, Gato del Sol IV, is moving forward. With a budget of $500,000 this time, the team aims to finish in the top third of the next race, and increase the car’s average speed to 35 mph.

Within the team there are three major areas of responsibility—mechanical, electrical, and financial. Kevin recently moved from the hands-on engineering side of the team to the business section. That part of the solar car team plans public events and helps line up donations and sponsorships. Combining engineering know-how with financial management expertise in this volunteer project has inspired Nick to continue his education after he graduates with his engineering degree in 2009. Nick intends to enter UK’s master’s of business administration program to learn more about the details of project management.

Small car, big opportunities
These experimental solar cars are delicate creatures—even with a driver, UK’s Gato del Sol only weighs 645 pounds. During the race, each car requires front and rear escort vehicles with flashers on top to make sure other conventional vehicles on the road don’t get too close or cause extra safety hazards.

And these solar cars don’t travel at dependably constant speeds. Even with on-board computers, the driver must make decisions about lowering speed to conserve the amount of energy available in the batteries that can be transferred to the wheels. With a dwindling power supply, Gato del Sol III crept over the finish line only going about 5 miles per hour. Slow, but just right for the other team members to run alongside as the car passed the checkered flag.

But a solar car competition isn’t about thrilling high speeds. It’s about the future of transportation—and the future of energy use.

Whenever the UK team takes the solar car to public events, Nick often ends up talking with curious folks about the practical applications for such a novelty. Nick notes three aspects of solar car technology that could eventually cross over to more conventional vehicles: improvements in aerodynamic shapes, more practical ways to use composite materials for lighter-weight, energy-saving vehicles, and better protection systems for lithium ion or lithium polymer batteries to prevent fires and other safety problems.

A fourth key issue is a better understanding of how solar cell technology could be incorporated into a vehicle that uses other energy systems. At least two global car manufacturers are investigating how solar panels mounted on a car’s exterior could be used to power non-propulsion systems, such as air conditioning or navigation tools, maybe the car’s radio or stereo. A car of the future could have many energy systems, each doing what it does best or most economically.

Dan Eberle, interim director of the Missouri Alternative and Renewable Energy Technology program at Crowder College, says, “People learn by doing. If we want the next generation to value living energy efficiently, then we have to give them the opportunity to practice it and experience it.”


Fully loaded, the University of Kentucky’s Gato del Sol III solar car includes:
• 645 pounds, including driver
• 480 solar cells
• 168 batteries
• No air conditioning

Find a complete list of specifications on the Web at

Next month: Batteries and Energy Storage


For UK solar car technical specs, videos, and blogs about the solar car challenge race read the online supplement that goes with this column.

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