Most solar cars have a relatively flat, wide shape to maximise the surface area for solar panels, but the Cambridge team hoping to become the first British winners of the World Solar Challenge have instead opted for a more aerodynamic teardrop design fitted with panels that move to follow the sun.
The prototype car, named “Resolution”, is being unveiled today in a road test at Millbrook Proving Ground, near Bedford, in advance of the World Solar Challenge in October, when 47 teams from 26 countries are due to race 3,000km across Australia from Darwin in the north to Adelaide in the south.
Keno Mario-Ghae, team manager for the Cambridge University Eco-Racing team that includes 60 students, said in a statement, ‘Resolution is different because she overcomes one of the main limitations that affect most solar cars.
‘Traditionally, the entire structure of a solar car has been based on a trade-off between aerodynamic performance and solar performance. That’s how they’ve been designed for the past 10 years, and that’s why they all tend to look the same.
‘We turned the concept on its head. Our reasoning is that solar performance needs to adapt to the movement of the sun, but the car needs a fixed shape to be at its most aerodynamic. To make the car as fast and powerful as possible, we needed to find a way to separate the two ideas out, rather than find a compromise between them.’
The team embedded the solar panels within an aft-facing tracking plate that follows the sun’s trajectory and moves the panels so they are optimally positioned at all times. They estimate this will give the car a power boost of 20 per cent.
This structure is placed under a canopy that forms part of the teardrop shape of the vehicle as a whole, encasing the solar panels so that power generation doesn’t compromise the car’s aerodynamics.
Resolution measures less than 5m in length, 0.8m across and about 1.1m in height, and the cockpit is only big enough for drivers under 5’ 3’’ (1.6m) in order to minimise weight and maximise speed.
The car weights 120kg and has a top speed of almost 140kph (87mph) using the up to 1.2kW of power available from the sun – equivalent to that of a powerful iron or vacuum cleaner.
The team said they achieve this by maximising efficiency wherever possible. For example, the motor is located in the hub of the wheel, eliminating the need for gears, chains or differentials that would lower the overall efficiency.
The vehicle has also been fitted with on-board telemetry, an intelligent cruise control system that takes into account traffic, weather and driving style, and will advise the team on how to optimise the vehicle’s efficiency during the race itself.
The World Solar Challenge has been running for over 25 years and past winners have included teams from General Motors, Honda, and for the last decade has been dominated by Delft University of Technology in the Netherlands and Tokai University in Japan, but no British team has ever won.
This year will be the third time that student engineers at Cambridge have taken part in the race. The first attempt, in 2009, was beset by battery issues and saw the team finish 14th out of 26. The second race the team entered in 2011 was hampered by bush fires and poor weather conditions that meant only seven teams finished.
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