Monday, 11 February 2013

Next generation solar cells: trapping sunlight with microbeads
29 Jan 2013

In five to seven years, solar cells will have become much cheaper and only one-twentieth as thick as current solar cells. The trick is to deceive the sunlight with microbeads. Nanoscientists are currently developing the next generation of solar cells, which will be twenty times thinner than current solar cells.

Over 90% of the current electricity generated by solar panels is made by silicon plates that are 200 micrometres thick. Several billion of these are produced every year. The problem is the large consumption of silicon: five grams per watt. 200 Alta power stations: This year, between five and ten billion solar panel units will be produced worldwide. This is the equivalent of 30 GW, or the capacity of 200 Alta power stations.

Though silicon is one of the most common elements on earth, pure silicon does not exist in nature. Silicon binds readily to other elements. In order for solar cells to function, the silicon plate must consist of at minimum 99,9999% silicon. You read that right: if the solar cell consists of more than one millionth other materials, it does not work.

Today, pure silicon is created in smelters at 2,000° Celsius. This requires a lot of energy. Factories supply silicon in bricks the size of a piece of firewood. They are then cut into slices thin enough for solar panels. Only half become solar cells. The rest turns into sawdust.

"About 100,000 tonnes of silicon are consumed every year. However, there is obviously something fundamentally wrong when half of the silicon must be thrown away during the manufacturing process", says Erik Marstein. He is the Head of the Norwegian Research Centre for Solar Cell Technology, the Head of Research for the solar cell unit at the Institute for Energy Technology (IFE) at Kjeller outside of Oslo, and an Associate Professor in the Department of Physics at the University of Oslo (UiO), Norway.

The price of solar cells is falling steadily. Today, solar panels cost a half € for every watt. Only four years ago, the price was two Euros per watt. "It is difficult to make money producing solar cells at current prices. To make money, solar cells must be manufactured much more cheaply".

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