UK students target solar cell efficiency record

Cambridge University students use space-grade silicon cells to compete in the World Solar Challenge

This solar powered car could break cell efficiency records. (Source: Cambridge University Eco Racing)

By Nilima Choudhury

A team of UK students are set to smash solar cell efficiency records with a new solar car that will be racing through the Australian outback in the World Solar Challenge.

Using space-grade silicon cells, the University of Cambridge team claim their car – named Resolution – could reach efficiencies of 36%, beating the current record of 29.1%.

“We’re currently exploring the option of registering it as a world record for the most efficient terrestrial solar array ever assembled,” said Yang Lu Technical director of the Cambridge University Eco Racing team.

The challenge is a biennial race from Darwin to Adelaide that first took place in 1987. The 3000 kilometre journey starts on 6 October, and will stretch competing cars to their limits.

The teardrop shaped car uses silicon solar cells, weighs 125 kilos and can reach speeds of 70-80mph. They expect to get through 48 ‘low rolling resistance’ tyres during the trip – each one costs £150.

The organisers stipulate solar cells cannot be larger than six square metres for cars using silicon photovoltaic (PV) cells, and no more than three square metres for those cars using gallium arsenide PV cells.

Small package

The team’s 2011 car Endeavour used silicon cells that produced an output of 1.0kW during the race. For the 2013 race they have plumped for a smaller but more efficient gallium arsenide array, allowing them to put the cells inside the car beneath a transluscent cover:

“It means that we can tilt our solar cells to track the sun. And this actually gained us about 20% extra power,” said Lu. “Our design focused on making the car as small as it can be there was no way we could fit six square metres.”

The team of drivers will also benefit from a race model based on the latest weather data – this will help the driver choose the best speed at each stage of the race.

For future races Lu said the team were considering producing a vehicle that would carry more people.

He says this could use concentrated solar power technology, which he believes would create a more sustainable and cheaper form of transport.

“We’re not just a team who build these solar cars. We’re exploring other technologies in terms of large scale solar generation in light weight electric vehicle design.”

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