USA UNITED STATES DEPARTMENT OF ENERGY SOLAR POWERED CARS AND BOATS ENERGY SAVERS | THE AUSTRALIAN AND AMERICAN WORLD SOLAR CHALLENGES.

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Solar-Powered Vehicles

Solar-powered vehicles (SPVs), such as cars, boats, bicycles, and even airplanes, use solar energy to either power an electric motor directly, and/or use solar energy to charge a battery, which powers the motor. They use an array of solar photovoltaic (PV) cells (or modules made of cells) that convert sunlight into electricity. The electricity either goes directly to an electric motor powering the vehicle, or to a special storage battery. The PV array can be built (integrated) onto the vehicle body itself, or fixed on a building or a vehicle shelter to charge an electric vehicle (EV) battery when it is parked. Other types of renewable energy sources, such as wind energy or hydropower, can also produce electricity cleanly to charge EV batteries.

SPVs that have a built-on PV array differ from conventional vehicles (and most EV's) in size, weight, maximum speed, and cost. The practicality of these types of SPVs is limited because solar cells only produce electricity when the sun is shining. Even then, a vehicle completely covered with solar cells receives only a small amount of solar energy each day, and converts an even smaller amount of that to useful energy. At present, most SPVs with built-on PV arrays are only used as research, development, and educational tools, and/or to participate in the various SPV races held around the world (see discussion below).

Solar Car Designs

Perhaps the first, totally solar-powered car, the "Bluebird," was built by Ed Passerini, in 1977. Mr. Passerini has also built several other small, lightweight, and relatively low-cost (under $10,000) solar cars. At the other end of the spectrum, are solar cars equipped with advanced technology and built with the backing of large automobile manufacturers, including General Motors (GM), Ford, and Honda. Some solar cars use silver-zinc batteries, which have several advantages over traditional lead-acid batteries: they are lighter, are more efficient, and accept higher rates of charging. However, they are very expensive, and may only be charged and discharged (cycled) a few times before they become unusable and require recycling. While most developers use crystalline silicon cells in their designs, GM has used the higher efficiency, but more costly, gallium arsenide cells. GM's Sunraycer has a 90 square-foot (8.4 square-meter[m²) curved solar array integrated into the tear-dropped shaped body of the car. GM spent $8 million developing the Sunraycer.

John Mitchell Systems designed a SPV with a PV array integrated into two vertical air foils. These act as a sail to provide aerodynamic thrusts. In tests, the vehicle achieved 30 miles per hour (mph; or 48 kilometers per hour [kph]) using wind power alone. Ford Motor Co., and others, have designed tilting arrays that track the sun.

Advances in lightweight structural materials have also contributed to improving solar car performance. The Sunraycer has an aluminum chassis and body made of two lightweight composite materials. While the car is 19.7 feet (6 meters [m]) long, 6.6 feet (2 m) wide, and 3.3 feet (1 m) high; the chassis weighs only 14 pounds (6.4 kilograms [kg]). The entire shell weighs less than 100 pounds (43.4 kg). The total weight of the vehicle, without the driver, is 390 pounds (177 kg).

Integration of PV Cells onto Conventional Cars

Kyocera Corporation developed a prototype solar-assisted electric commuter vehicle. It is a small, two-seat hatchback, and weighs about 1,200 pounds (544 kg). With its nickel-zinc batteries fully charged, the car has a top speed of 40 mph (64 kph) and a driving range of 70 miles (112 km). A 23 square feet (2.1 m²) PV array can extend this range up to 100 miles (160.9 km) on a sunny day.

Two auto manufacturers have introduced models with an optional PV panel incorporated into a sunroof. The PV panel runs a ventilation fan to cool the car when parked in the sun. Other potential uses of solar cells are for vehicle starting battery charge maintenance systems. PV battery charging arrays have been designed for rear spoilers, and a "solar wing," a feature similar to a rear spoiler that provides a downward force on the vehicle to help improve its traction on racetracks and highways.

PV EV Battery Charging

The Sacramento Municipal Utility District built a PV array that it uses to help charge several of the electric cars and trucks that it owns. The array also shelters the vehicles when they are being recharged. Several other shelter/arrays have been built around the country.

Solar Powered Bicycles, Boats, and Aircraft

The city of Palm Springs, California, has constructed 16 charging stations for electric bicycles around the city. The city's police department and many commuters use the stations daily. The stations have lockers for electric bikes with an electrical outlet that is connected to a pole-mounted PV array. When parked and "plugged in," the array charges a bike's battery.

In 1974, two brothers, Robert and Roland Boucher, flew the Sunrise I, an extremely light-weight, remote controlled, pilot-less aircraft powered by a PV array on the wings, to a height of 300 feet. The next year, their more advanced Sunrise II flew to 17,000 feet (5,000 meters). The US Air Force funded the development of these solar powered aircraft with the hopes of using them as spy planes. In 1980, the son of Paul MacCready, piloted a smaller, sun-powered version of the pedal-powered Gossamer Albatross (which cyclist/hang glider pilot Brian Allen had pedaled across the English Channel). With support from Dupont, MacCready built the Solar Challenger, and crossed the English Channel on July 21, 1981. It attained an average speed of 50 mph (80 kph), and at about 12,000 feet (3658 meters).

The National Aeronautics and Space Administration (NASA) has sponsored the development of remote controlled, pilot-less solar powered aircraft since the early 1990's. These craft are essentially "flying wings" covered with solar cells that power motor driven propellers placed along the wing. The initial version was the Pathfinder, which achieved an altitude of 50,000 feet (15,240 meters) in 1995. The next version, Pathfinder Plus reached 86,000 feet (26,200 meters) in 1998. The current versions, Centurion and Helios, were flown in 1998 and 1999 respectively. In 2001, Helios flew to a record 96,863 feet (29,524 meters). These craft are alternatives to space-based remote sensing satellites. For more information see NASA Dryden Flight Research Center in the Source List below.

Solar/battery powered boats are another type of SPV. PV (and wind energy) systems can charge batteries to run small electric lights and appliances, and even to run electric motors to move the boat itself. The Minnesota Renewable Energy Society sponsors an annual solar-powered boat race in Minnesota (see below).

Solar Car Races

SPV races serve as proving grounds for new solar vehicle technologies, and help expose the public to the idea of solar energy as a power source.

One of the first solar car races was the World Solar Challenge, the first transcontinental solar vehicle race. The first race was in 1983 and crossed 1,872 miles (3,012 km) of rough Australian terrain. The race is held every three years. In 1987, the GM-sponsored Sunraycer won, finishing more than 600 miles (965 km) ahead of its nearest competitor. In 1990, The Spirit of Biel II, an entry from a Swiss school, won the race. In 1993, Honda's vehicle won with an average speed of 52.79 mph (84.96 kph). In 1996, Honda won again, finishing with an average speed of 55.77 mph (89.76 kph). In 1999, team Aurora, won the 1,870 mile (3,010 km) race from Darwin to Adelaide in 41 hours and 6 minutes, at an average speed of 45 mph (73 kph). The 2003 World Solar Challenge was from Darwin to Adelaide, October 18-28. The Nuon Solar Team won in 30 hours 54 minutes, with an average speed of 60.4 mph (97 kph).

For more information on the World Solar Challenge (and World Solar Cycle Challenge), click the link above.

In the United States, interest in solar car races has steadily increased. The first American Solar Cup was held in September 1988 in Visalia, California. The racecourse covered 160 miles (257 km). Of the seven cars that competed, only the student-built, Massachusetts Institute of Technology (MIT) entry finished. The California Highway Patrol escorts clocked the car at speeds up to 85 mph (137 kph)!

The Sunrayce is exclusively for vehicles powered directly by the sun. The first race was in 1990 from Florida's EPCOT Center to GM's technical center in Warren, Michigan in July 1990. General Motors, the US Department of Energy (DOE), and the Society of Automotive Engineers (SAE) sponsored the event. Thirty-two university groups competed. The cars spent 11 days racing, and despite several days of rain and clouds, all but one of the teams completed the race. The University of Michigan team, which included over 100 students, won. They raised and spent more than $800,000 on their vehicle.

Sunrayce 93 was just as exciting as Sunrayce 90. The rules were changed to try to give smaller schools a better chance of beating large, well-financed teams. The race was close until the fifth day, when bad weather forced everyone to stop except the University of Michigan team, which won again. The University of California at Poly-Pomona team was a close second. Michigan again spent the most ($575,000) on their car. The University of Puerto Rico spent the least ($25,000) and finished last.

Sunrayce 95 began in Indianapolis, Indiana, on June 20, and finished 1,500 miles (2,414 km) later in Golden, Colorado on June 29. Thirty-eight colleges and universities competed. The MIT team won with an average speed of 37.23 mph (60 kph). The University of Minnesota car was only about 19 minutes behind. The University of California at Poly-Pomona finished third, and George Washington University fourth.

Sunrayce 97 started June 19 in Indianapolis, Indiana, and ended in Colorado Springs, Colorado. Thirty-six teams competed in ten exciting days of racing. The event ended with bright sunny skies in Colorado Springs with California State University - Los Angeles as the overall winner, with a record setting pace averaging 43.29 mph (69 kph), and total time of 28:41:24 hours. MIT was a close second with a total time of 29:00:20 hours, followed by Stanford University/UC - Berkeley at 29:33:15 hours. In fourth was Texas A&M with a time of 29:47:21 hours.

Sunrayce 99 was held from June 20th to the 29th, 1999, from Washington, DC to Orlando, Florida. The winner was the "Rolla" SPV designed by a team at the University of Missouri. The Rolla covered the approximately 1,300 mile (2092 km) course in 56 hours, 16 minutes and 44 seconds at an average speed of 25.3 mph (37 kph), and finished about one hour and twenty-six minutes ahead of Queen's University, the second-place finisher. Cloudy, rainy weather throughout the race dampened performance relative to previous races.

After the conclusion of Sunrayce 99, General Motors Corporation, a principal sponsor of Sunrayce, and which "owned" the title of the race, decided to discontinue its sponsorship. The concept of a SPV "racye" continues as a cross-continental race under the name American Solar Challenge.

The first American Solar Challenge, sponsored by the U.S. Department of Energy, the National Renewable Energy Laboratory, and Terion, Inc., was held from July 15th to the 25th, 2001, covering 2,300 miles (3,700 km) from Chicago, Illinois to Claremont, California. This challenging racecourse followed what remains of Route 66, passing through the plains, mountains, and deserts of seven states. The University of Michigan's entry, the M-Pulse, won with a time of 56 hours, 10 minutes and 46 seconds, at an average speed of 40 miles per hour. The University of Missouri at Rolla was second with a time of 57:30:52, and the University of Waterloo, Ontario, Canada, was third with a time of 62:00:18. For details on the American Solar Challenge contact Formula Sun (see Source List below).

The 2003 American Solar Challenge was again from Chicago to Los Angeles, covering 2,300 miles. The University of Missouri-Rolla came from second place in the previous years race to take first place, averaging nearly 43.3 mph and beating the record time from the 2001 race by more than four hours. The University of Minnesota came in second, nearly five hours behind Missouri-Rolla, while the University of Waterloo again took third place.

The Formula Sun Grand Prix is an annual closed-course solar car "rayce" and a qualifying event for the American Solar Challenge. Results on these races are available at the Formula Sun web site (see Source List below). For details on the American Solar Challenge contact Formula Sun (see Source List below).

The Tour de Sol is a 250 mile (400 km) race held annually since 1985 in Switzerland. The race, organized by engineering students, differs from the World Solar Challenge in that it seeks to produce practical commuting EV's that travel at average speeds.

The American Tour de Sol, inspired by the Swiss Tour de Sol, is an annual race that highlights "green vehicles", including electric/battery and fuel cell-powered vehicles. The race is usually held in the Northeastern US. For more information on the American Tour de Sol or the Green Transportation Festivals, contact the Northeast Sustainable Energy Association (see NE Sun/NSEA in the Source List below).

Other Solar Car Races

The Junior Solar Sprint (JSS) is a model solar car race sponsored by the U.S. Department of Energy. The JSS is a classroom-based, hands-on educational program for 6th, 7th, and 8th grade students. JSS student teams apply math, science, and creativity to construct model solar-powered cars and race them in interscholastic competitions hosted within their schools or within their states or regions. JSS began in 1990 as a single demonstration race and expanded to 10 regional competitions in 1991. The program now uses public and private sector support to improve education in middle/junior high schools across the nation. In recent years, the event grew to 83 host sites in 26 states involving 100,000 students and 15,000 teachers.

For more information on the JSS, contact Linda Lung, Office of Education Programs, NREL.

The Winston Solar Challenge Project is an international education program designed to teach high school students the physics and technology associated with road-worthy solar cars. It's objective is to encourage student interest in science, engineering and solar technology. Emphasis is on sharing knowledge and developing of new friendships rather than on pure competition. For more information, contact:
Lehman Marks, The Winston School.

Solar Bicycle Races

Solar Bike Rayce USA (SBR) is an annual closed-course solar bike race held during the Formula Sun Grand Prix car race (see above). The SBR is also the qualifying event for the Solar Express, a 373 mile (600 km) solar bike "rayce" from Topeka, Kansas to Jefferson City, Missouri. For details on these races contact Formula Sun (see Source List below).

Solar Boat Regattas

The Minnesota Renewable Energy Society (RES) has sponsored annual solar powered boat races in Minnesota since 1992. For more information, contact: Minnesota RES, attention Allan Meyer, 25921 Dodd Blvd, Lakeville, MN 55044, and the article "Running … Boat Regatta," below.

Another solar powered boat regatta is the Solar Splash, an international collegiate solar- powered boat race. The 2003 race will be held June 18-22, in Buffalo, NY. For details, contact webmaster@solarsplash.com.

Bibliography

The following articles and publications provide additional information about SPVs and races. Please see the Source List below for availability.

Articles from Home Power:

"The Biggest, Solar Electric Boat this Side of the Mississippi," S. Cooper, (No. 57), pp. 28-30, Feb/Mar 1997.

"From Horsepower to Sunpower on the Mother Road," S. Prange, (No. 85) pp. 104-109, Oct/Nov 2001.

"G'Day Sun! Solar Car Race in Australia," T. Pereira, (No. 78) pp. 68-72, Aug/Sept 2000.

"The Long, Long Road of Solar Racing, S. Prange, (No. 60) pp. 60-63, Aug/Sept 1997.

"Running the Minnesota Solar Boat Regatta," R. Jacobson and T. Roark, (No. 59) pp. 56-59, Jun/Jul 1997.

"Run with the Sun: PV-Powered Wheels in the Alaskan Bush," E. LaChapelle, (No. 69) pp. 8-11, Feb/Mar 1999.

"Solar Cars for Pleasure or Competition," T. Sorenson, (No. 53) pp. 64-66, Jun/Jul 1996.

"Solar Trailblazer: PV Charges EV in Palo Alto, CA," W. Beckett (No. 78) pp. 10-16, Aug/Sept 2000.

Articles from Solar Today:

"Affordable, Homemade Solar Cars," E. Passerini, (10:4) pp. 24-25, Jul/Aug 1996.

"Helios: A State-of-the-Art Solar Plane," M. Hagland, (15:3) pp. 32-35, May/June 2001.

"The Wright Brothers of Solar Aircraft," J. Perlin, (13: 2) pp. 16-17, Mar/Apr 1999.

Miscellaneous Articles:

"High Efficiency Solar Cells Win the World Solar Challenge," R. MacDougall, Northern California Sun, (1:22) pp. 8, Winter 1997.

"Solar Powered Transportation In America," R. Cotter, Northeast Sun, (7:2) pp. 10-12, May/June 1989.

Technical Reports (available from NTIS See source list below)

Sunrayce 93 Technical Report, R. King, et al., National Renewable Energy Laboratory (NREL), 1993. 90 pp. NTIS Order No. DE94006927.

Sunrayce 1995 Technical Report, R. King, et al., NREL, 1996. 76 pp. NTIS Order No. DE96007868.

Sunrayce 95: Working Safely with Lead Acid Batteries and Photovoltaic Power Systems, D. Phillips, NREL, 1995. 11 pp. NTIS Order No. DE94013536.

Source List

Solar powered car racing events continue to gain in popularity the world over. They say racing improves the breed and this is no exception. What is clear from the make up of the teams below, is that most of the development of solar racers is undertaken by university teams. It seems this is a young engineers sport and that the cars of the future are being developed without any major assistance from the big car makers, but with sponsorship from educational institutions and business.

ANNE E. B. II

BEAM MACHINE

COLUMBIA

COUGAR CRUISER

DRIFTER

ESTEBAN III

FUJI DESERT ROSE

FUSION

GATO DEL SOL II

GEMINI

HONDA

MAD DOG

KEYSTONE

MERCURY I

MIDNIGHT SUN VIII

MOMENTUM

NED and KELLY

NUNA I

NUNA II 2003

NU'NERGY

PARAGON

PHOENIX

QUIET ACHIEVER

RA 6

RED RIVER RAYCER

SOLAR MINER

SOLAR PHANTOM

SOLAR STEER

SOL OF AUBURN

SOLSTICE

SPOT 2

SUNRAYCER

SUNSEEKER 05

SUNSWIFT

SUNTIGER VI

TESSERACT

THE JOHN LEE

ULTRAVIOLET

Aristotle University of Thessaloniki, Helios

Arizona Solar Racing Team - USA

Auburn University

Aurora Team, Australia

Blue Sky Solar Racing Toronto

Bochum Solar Car Team

CalSol

Clarkson Solar Car Team, USA

Dell Winston Solar Car Challenge

Drexel SunDragon Home Page

École Polytechnique de Montréal

Eko-Auto Poland

George Washington Uni Solar Car

Helios - France

Helios Lille

Heliodet, Germany

Heliotrope Toulouse

Illinois State University

Iowa State University

Jonasun Japan

Kansas State Uni Solar Racing Team

Massachusetts Institute of Technology

McMaster University Home

Midnight Sun Waterloo

Northwestern University

Nuon Solar Team, Netherlands

Osaka Sangyo University, Japan

Principia College U.S.A.

Purdue University

Queen's University

Radiance Canada

Red River College

S. Australia Solar Car Consortium

Southern Illinois Uni Edwardsville

South Bank University, UK

Southern Taiwan University Tech

Spirit of Massachusetts Specs

Stanford University

Sunshark - University Queensland

Tamagawa University - Japan

The Power of One Solar Car Project

Tufts University Nerd Girls

University of Arizona

University of Calgary

University of Kentucky

UMass Lowell Solar Racing Team

University of Michigan - Michigan

University of Minnesota

University of Missouri - Columbia

University of Missouri - Rolla

Uni of New South Wales SCR Team

University of Patras, Hermes

University of Pennsylvania

University of Texas at Austin

University of Waterloo

University of Western Ontario

USP Solar Car Team

Western Michigan University

Winston School

Yale University Team Lux

Apart from winning events, the outright speed of the competing vehicles is rising. Aurora set a record on 16 march 2002, achieving 53.56 mph or 86.20 kph. Then Delft University attained a speed of more than 100 kph with 'Nuna' and cut their overall time with Nuna II in October 2003.

However, according to the Guinness Book of Records the fastest solar powered vehicle is GM's 'Sunraycer' with a speed of 78.39 km/hr (48.71 mph) set on June 24 1988. Who is right and which record is official?

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