A solar vehicle or solar electric vehicle is an electric vehicle powered completely or significantly by direct solar energy. Usually, photovoltaic (PV) cells contained in solar panels convert the sun's energy directly into electric energy.
The term "solar vehicle" usually implies that solar energy is used to power all or part of a vehicle's propulsion. Solar power may also be used to provide power for communications or controls or other auxiliary functions.
Solar vehicles are not sold as practical day-to-day transportation devices at present, but are primarily demonstration vehicles and engineering exercises, often sponsored by government agencies. However, indirectly solar-charged vehicles are widespread and solar boats are available commercially.
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Solar cars
Solar cars are electric cars that use photovoltaic (PV) cells to convert sunlight into electrical power to charge the car's battery and to power the car's electric motors.
Solar cars have been designed for solar car races and for public use. Solar vehicles must be light and efficient to get the best range from their limited captured power. pound or even vehicles would be less practical because the limited solar power would not take them as far. Most student built solar cars lack the safety and convenience features of conventional vehicles and are thus not street legal.
The first solar family car, Stella, was built in 2013 by students in the Netherlands. This vehicle is capable of on one charge during sunlight. It weighs and has a 1.5 kWh solar array.
Stella Lux, the successor to Stella, broke a record with a single-charge range. During racing Stella Lux is capable of during daylight. At Stella Lux has infinite range. This is again due to high efficiency including a Coefficient of drag of 0.16.
The average family who never drive more than a day would never need to charge from the mains. They would only plug in if they wanted to return energy to the grid.
Solar race cars are often fitted with gauges and/or wireless telemetry, to carefully monitor the car's energy consumption, solar energy capture and other parameters. Wireless telemetry is typically preferred as it frees the driver to concentrate on driving, which can be dangerous in such a car without safety features. The Solar Electric Vehicle system was designed and engineered as an easy to install (2 to 3 hours) integrated accessory system with a custom molded low profile solar module, supplemental battery pack and charge controlling system.
Some of the students that built Stella Lux founded a company, Lightyear, to commercialize this technology.
An American company, Aptera Motors, has also been founded to make efficient solar electric cars for the public. As of January 2023, first customer availability is expected in 2024.
In Germany the company Sono Motors was working on a solar electric vehicle, the Sono Motors Sion, that was supposed to be on the market in 2023. However in February 2023, Sono Motors terminated the Sion program and announced it would focus exclusively on being a Solar Tech Company.
Note that all battery-powered electric vehicles may also use external solar array sourced electricity to recharge. Such arrays may also be connected to the general electrical distribution grid.
Solar buses
Solar buses are propulsed by solar energy, all or part of which is collected from stationary solar panel installations. The Tindo bus is a 100% solar bus that operates as free public transport service in Adelaide City as an initiative of the City Council. Bus services which use electric buses that are partially powered by solar panels installed on the bus roof, intended to reduce energy consumption and to prolong the life cycle of the rechargeable battery of the electric bus, have been put in place in China.
Solar buses are to be distinguished from conventional buses in which electric functions of the bus such as lighting, heating or air-conditioning, but not the propulsion itself, are fed by solar energy. Such systems are more widespread as they allow bus companies to meet specific regulations, for example the anti-idling laws that are in force in several of the US states, and can be retrofitted to existing vehicle batteries without changing the conventional engine.