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On wavelength

with the Sun

Today, a lot of the sunlight is lost in standard solar cells because the wavelength is too long. In the SunTune project researchers want to develop techniques to convert more of the rays into usable light.

If we could convert the energy of all sun rays into electricity, we would be able to cover the world’s power consumption many times over. The SunTune project aims at boosting efficiency of solar cells so that far more of the Sun’s energy can be exploited in the future.

The Earth is enveloped by a vast blaze of light from the Sun, supplying all the energy we could ever dream of. Every year, the Sun provides us with an amount of energy that is almost 10,000 times as much as our annual global energy consumption. Currently it is possible to use solar cells to harvest sunlight and convert it into electricity but with a loss of more than 70 percent. This loss could be reduced if we were to succeed in getting solar cells to utilise a larger part of the solar spectrum. More efficient solar cells would be an important step towards Denmark’s goal of being independent of fossil fuels by 2050.

Changing the colour spectrum of sunlight
A research team based at Aarhus University will now try to ‘tune’ into the Sun’s wavelength. The consortium behind the project consists of a unique collection of Danish and foreign researchers and representatives from Danish companies. Some of these actively manufacture solar cells while others would like to use them for electricity production.

One reason for the low efficiency of standard solar cells is that a large part of the solar energy is in long-wavelength light, which is not converted to electricity in solar cells. If we want to make solar energy more cost-effective in the future, the trick is therefore to capture a larger portion of the light’s energy.

“We want to develop new nanostructured materials that can change the colour spectrum of sunlight to better match the absorption of solar cells. This can boost the efficiency of the existing technologies,” says Associate Professor Søren Peder Madsen.  

The ambition of the SunTune project is to find ways to utilise long-wavelength light from the Sun. This will take place by changing the colour spectrum for sunlight in the cell so that it better matches the area where power generation is effective.

The researchers hope to be able to increase efficiency by as much as four per cent points for silicon solar cells, and potentially even more for other types of solar cells.