Solar vehicle

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See also: Photovoltaics in transport

A solar vehicle is an electric vehicle powered by solar energy obtained from solar panels on the surface of the vehicle. Photovoltaic (PV) cells convert the sun's energy directly into electrical energy. Solar vehicles are not practical day-to-day transportation devices at present, but are primarily demonstration vehicles and engineering exercises, often sponsored by government agencies.

[edit] Solar cars

Solar photovoltaicsassisted electric powered India's first Quadrcycle developed since 1996, in Gujarat state's SURAT city.[1]

See also: Solar car racing

Solar cars combine technology typically used in the aerospace, bicycle, alternative energy and automotive industries. The design of a solar vehicle is usually severely limited by the energy input into the car (batteries and power from the sun). Virtually all solar cars ever built have been for the purpose of solar car races (with notable exceptions).

Like many race cars, the driver's cockpit usually only contains room for one person, although a few cars do contain room for a second passenger. They contain some of the features available to drivers of traditional vehicles such as brakes, accelerator, turn signals, rear view mirrors (or camera), ventilation, and sometimes cruise control. A radio for communication with their support crews is almost always included.

Solar cars are often fitted with gauges as seen in conventional cars. Aside from keeping the car on the road, the driver's main priority is to keep an eye on these gauges to spot possible problems. Cars without gauges available for the driver will almost always feature wireless telemetry. Wireless telemetry allows the driver's team to monitor the car's energy consumption, solar energy capture and other parameters and free the driver to concentrate on just driving.

[edit] Production

Tesla Motors is offering a modestly sized and priced solar panel from SolarCity. It can be installed on the car roof in an out of the way location, because of its small size, or set up as a carport and will generate about 50 miles per day of renewable electricity. [1]

[edit] Electrical and mechanical systems

The electrical system is the most important part of the car's systems as it controls all of the power that comes into and leaves the system. The battery pack plays the same role in a solar car that a petrol tank plays in a normal car in storing power for future use. Solar cars use a range of batteries including lead-acid batteries, nickel-metal hydride batteries (NiMH), Nickel-Cadmium batteries (NiCd), Lithium ion batteries and Lithium polymer batteries.

Many solar race cars have complex data acquisition systems that monitor the whole electrical system while even the most basic cars have systems that provide information on battery voltage and current to the driver. One such system utilizes Controller Area Network (CAN).

The mechanical systems of a solar car are designed to keep friction and weight to a minimum while maintaining strength. Designers normally use titanium and composites to ensure a good strength-to-weight ratio.

Solar cars usually have three wheels, but some have four. Three wheelers usually have two front wheels and one rear wheel: the front wheels steer and the rear wheel follows. Four wheel vehicles are set up like normal cars or similarly to three wheeled vehicles with the two rear wheels close together.

[edit] Solar array

The solar array consists of hundreds of photovoltaic solar cells converting sunlight into electricity. Cars can use a variety of solar cell technologies; most often polycrystalline silicon, monocrystalline silicon, or gallium arsenide.

The power produced by the solar array depends on the weather conditions, the position of the sun and the capacity of the array. At noon on a bright day, a good array can produce over 2 kilowatts (2.6 hp).

Some cars have employed free standing or integrated sails to harness wind energy.[2]

[edit] Races

Solar cars from University of Michigan and University of Minnesota heading west toward the finish line in the 2005 North American Solar Challenge.
Solar cars from University of Michigan and University of Minnesota heading west toward the finish line in the 2005 North American Solar Challenge.
Main article: Solar car racing

The two most notable solar car races are the World Solar Challenge and the North American Solar Challenge, overland road rally-style competitions contested by a variety of university and corporate teams.

The World Solar Challenge features a field of competitors from around the world who race to cross the Australian continent, over a distance of 3000 km. The increasingly high speeds of the 2005 race participants has led to the rules being changed for future solar cars starting in the 2007 race.

The North American Solar Challenge, previously known as the 'American Solar Challenge' and 'Sunrayce USA', features mostly collegiate teams racing in timed intervals in the United States and Canada. The next North American Solar Challenge will run from June 13-22, 2008, from Dallas, Texas to Calgary, Alberta.[3]

There are other distance races, such as Suzuka, Phaethon, and the World Solar Rally. Suzuka is a yearly track race in Japan and Phaethon was part of the Cultural Olympiad in Greece right before the 2004 Olympics.

[edit] Solar bicycles and motorcycles

The first solar "cars" were actually tricycles or quadricycles built with bicycle technology. These were called solarmobiles at the first solar race, the Tour de Sol in Switzerland in 1985 with about 60 participants, 30 using exclusively solar power and 30 solar-human-powered hybrids. A few true solar bicycles were built, either with a large solar roof, a small rear panel, or a trailer with a solar panel. Later more practical solar bicycles were built with foldable panels to be set up only during parking. Even later the panels were left at home, feeding into the electric mains, and the bicycles charged from the mains. Today highly developed electric bicycles are available and these use so little power that it costs little to buy the equivalent amount of solar electricity. The "solar" has evolved from actual hardware to an indirect accounting system. The same system also works for electric motorcycles, which were also first developed for the Tour de Sol. This is rapidly becoming an era of solar production.

[edit] Practical applications

The Venturi Astrolab in 2006 was hailed as the world's first commercial electro-solar hybrid car due to be released in January 2008.[4]

In May 2007 a partnership of Canadian companies lead by Hymotion altered a Toyota Prius to use solar cells to generate up to 240 watts of electrical power in full sunshine. This is reported as permitting up to 15 km extra range on a sunny summer day[5] while using only the electric motors.

Louis Palmer standing in the Solartaxi.
Louis Palmer standing in the Solartaxi.

One practical application for solar powered vehicles is possibly golf carts, some of which are used relatively little but spend most of their time parked in the sun.

An inventor from Michigan, USA has built a street legal, licensed, insured, solar charged electric scooter. It has a top speed controlled at a bit over 30 mph, and uses fold-out solar panels to charge the batteries while parked.[6]

A Swiss project, Solartaxi, seeks to build a road-worthy solar car with a trailer, carrying a 6 m² sized solar array. The Solartaxi has Zebra batteries, which permit a range of 400 km without recharging. The car can also run for 200 km without the trailer. Its maximum speed is 90 km/h. The car weighs 500 kg and the trailer weighs 200 kg. According to the team leader, the car in mass production could be produced for 6000 Euro. Solartaxi toured the World in December 2007 to encourage people in pursuing alternatives to fossil fuel.

[edit] Limitations and challenges

Battery electric vehicles fitted with solar cells would extend their range and allow recharging while parked anywhere in the sun. However, with present and near-term engineering considerations, it seems that the more likely place for solar cells will generally be on the roofs of buildings, where they are always exposed to the sky and weight is largely irrelevant, rather than on vehicle roofs, where size is limited. Energy from rooftop panels can be stored in batteries for future use.

[edit] See also

[edit] References

  1. ^ Exclusive Q & A with Elon Musk on the Tesla Roadster and the future of EVs - AutoblogGreen
  2. ^ The Leading Edge, Tamai, Goro, Robert Bently, Inc., 1999, p. 137
  3. ^ Official NASC Website
  4. ^ The first commercial solar-electric hybrid car
  5. ^ Hymotion modified Prius using solar power
  6. ^ PVScooter

[edit] External links

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