Lego-like design improves solar panel efficiency

18 October 2013
By Tereza Pultarova
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Covering the surface of solar panels with tiny lego-like bricks of aluminium can increase efficiency and reduce cost

Covering the surface of solar panels with tiny lego-like bricks of aluminium can increase efficiency and reduce cost

A 22 per-cent increase in solar panel efficiency has been achieved by UK scientists after they covered the surface of those panels with tiny aluminium studs.

The team from Imperial College London has attached rows of 100 nanometres wide aluminium cylinders onto the surface of the solar panels. By doing so, they have managed to change the course of light rays passing through the material, trapping them inside the absorbing layer, thus increasing the panels’ efficiency.

Such a design, resembling at the microscopic level interlocking LEGO building bricks, allows decreasing the amount of the absorbing material used while maintaining high efficiency levels.

"In recent years both the efficiency and cost of commercial solar panels have improved but they remain expensive compared to fossil fuels,” said Dr Nicholas Hylton from the Department of Physics at Imperial College London, the main author of a study published in the journal Scientific Reports.

“As the absorbing material alone can make up half the cost of a solar panel our aim has been to reduce to a minimum the amount that is needed," he said.

Most solar cells used in homes and industry are made using thick layers of material to absorb sunlight. The high costs of these panels, however, have so far been the major limiting factor preventing wider spread of the technology.

Low cost alternatives exist already, using thinner layers of light-absorbing substances. But the efficiency of these panels has been questioned.

In the past, scientists have tried to improve the performance of solar panels using studs of gold and silver to bend the light inside the panels. However, the results were rather disappointing as those metals absorbed part of the light before it even entered the solar panel, decreasing instead of increasing the amount of energy produced.

"The key to understanding these new results is in the way the internal structures of these metals interact with light,” Hylton said, explaining why the experiments with aluminium have been more successful.

“Gold and silver both have a strong effect on passing light rays, which can penetrate into the tiny studs and be absorbed, whereas aluminium has a different interaction and merely bends and scatters light as it travels past them into the solar cells."

The lower price of aluminium compared with silver and gold makes the new design even more attractive.

"The success of our technology, in combination with modern anti-reflection coatings, will take us a long way down the path towards highly efficient and thin solar cells that could be available at a competitive price," Hylton believes.

The researchers hope that in the future, they will be able to build flexible solar panels that could be attached to any flat or curved surface, which could be used to power everything from domestic appliances to portable electronics like laptops.

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