One of the proposed ways to extend the range of an electric car is through the addition of solar panels. A solar cell or photovoltaic (PV) cell is a device that converts light energy into electrical energy by the photovoltaic effect, a solar panel is a group of solar cells packaged together into one unit. Thus a vehicle (or any area) covered with solar panels exposed to sunlight will produce usable electric energy. In an EV this means that solar panels can be used either for on board charging or directly powering the controller/motor. PV cells are a non polluting renewable source of electricity with no moving parts and little required maintenance.
Common Questions About Solar Power and EVs.
Can an EV run purely on the energy generated by solar power at highway speeds?
Yes! Purpose built vehicles are able to achieve very impressive speeds using just the power of the sun. In the World Solar Challenge these solar cars compete against each other in a race across Australia running purely on sunlight and a small battery pack. The winner of the 2007 race, the Dutch Nuon Solar team, averaged 90km/h (56mph) in their solar car Nuna4 pictured below:
Can a normal EV conversion run purely on the energy generated by solar power at highway speeds?
No. The reason that these solar cars can travel at such impressive speeds is because they are some of the most efficient vehicles in the world. These cars can travel at highway speeds using about the same amount of energy as your hair dryer, about 10% of the energy required by a normal sized car. They have extremely efficient solar cells covering 8m2 (86 sqft) to gain as much power as possible. Using Solar Cells on a standard conversion will give around a 5-10% increase in range and the ability to trickle charge the batteries when parked in the sun but not yield enough energy for anywhere near highway speeds.
Why aren't Solar panels a viable option as a range extender?
The reason is due to the power to weight (and cost) ratio of solar panels:
'For some figures, typically you could fit about 200W of solar panels onto a car. Solar panels generally provide the equivalent of 5 hours at their rated power per day, i.e about 1kWh for a 200W panel per day, which is about 5km of extra range in a small vehicle. 5km may sound somewhat useful, but 1kWh worth of extra batteries weighs and costs less than a 200W solar panel! Also unless you're very careful with your installation, the increase in aerodynamic drag will quickly negate any extra range they can provide.*'
Yes. There are some enthusiasts who have installed solar panels on their EVs with some success. For example the University of Maine Solar Vehicle Team added a substantial 1kW solar array to their Chevy S-10 EV which gave them a 10-15 mile range using solar power alone at moderate speeds compared to 100 miles with the battery pack.