So what is solar energy and how does it power cars?
Although our sun is more than 150-million kilometres away, it provides life on earth by way of heat and light energy. According to the law of conservation of energy, the total energy of a system remains constant, though energy may transform from one form to another.
All solar cars are actually electric powered cars that run using solar or light energy converted to electricity through a solar cell. Typical solar cars use a mass of solar cells consolidated into a solar panel. The most developed silicon solar cells are about 22% efficient, which means 22% of the solar or light energy falling on the panel is converted into electricity at mid-day, providing about 220W per m2 of panel.
The Sasol Solar Challenge is an endurance race which pushes the boundaries of solar technology. To make the challenge fair for all, the maximum panel size stipulated in the rules is 9m2, which provides 1980W or nearly 2kW energy to each car. The technology used during the challenge could one day be incorporated into solar powered vehicles that will be our everyday transport.
Some solar facts:
- Energy from the sun is measured in kilowatts per hour (kWh)
- Most solar cars have solar cells capturing energy, electric motors driving the wheels and a battery to either store energy when not needed or to give energy when more is needed than the sun can provide
- Solar cars can drive at night, as the battery in a solar car is the energy bank
- Careful planning can allow the solar car to bank energy during the day, which can then be used at night
- Solar cars can reach speeds of up to 160km/h, but at this speed cars are not very efficient, so normally the speed is determined by the driver’s strategy which considers amongst other things, distance travelled and how much sun is available on a given day
- The design of a solar car is driven by energy efficiency and how energy is converted into the distance the car has to overcome, its mass and that of the driver, and the conditions and topography of the road