A tiny photovoltaic cell brought the 2012 German Environmental Award, the largest award for environmental work given in Europe, to Andreas Bett. Together with his co-workers- Hansjörg Lerchenmüller and Günther Cramer, Bett has spent the last 25 years developing these multi-junction solar cells of the future.
What makes these cells special, is their ability to transform the entire spectrum of sunlight into energy, unlike conventional cells. This is achieved through the use of three different semi-conducting materials: gallium-indium-phosphide, gallium-indium-arsenide and germanium.
While silicon transforms light in a small part of the spectrum, these three allow much greater coverage, which means 10% increased cell efficiency.
The three semi-conductor structures are placed on top of each other in order to level the peaks. The top one uses the short blue wavelengths of light, the middle transforms light in the green wavelengths, and the lowest one makes use of the long, infrared wavelengths. This is a ground-breaking innovation that has never been demonstrated before.
The first thought of course is the cost of making these cells. Yes, the three different semi-conductors increase the price a lot, however Bett has the solution to this problem too. He claims that if the sunlight is concentrated using a cheap optical lens and it is directed towards the very thin and small semi-conductor surface, the power that is generated is cost-effective.
Bett is very positive about the future of these solar cells. He predicts that in a few years, the share of the solar market that belongs to these cells would gain up to 15%. For them to work to their full capacity, however, there is a need of clear blue sky and plenty of direct sunlight. This will allow the optical lens to capture and guide light more effectively, ensuring optimal function of the cells.
Therefore, it is no surprise that the engineers involved in the manufacturing of this concentrator photovoltaic technology have placed their bets on land along the world’s Sun Belt.