Trade.Information

Topic Name: Third-generation solar cells

Category: Solar cells

Research persons:

Location: Gemini, SINTEF, N-7465 Trondheim, Norway, Norway

Details

Today the solar cells have an effectiveness of 17% if it is considered that 100% represent the energy of the sunlight converted into electricity. There are two types of solar cells, the cells of first and second generation. The most important difference is their production cost. The cells of first generation are made up of simple silica crystals and are very expensive to produce. Whereas the production of cells of second generation requires a cost much less important. Also the price by produced Watt is reduced.
The University of Trondheim works on the creation of solar cells of third generation. The effectiveness of these new cells would be well above the preceding ones. “Theoretically should reach an effectiveness of 60% to us or more. In practice we hope to reach 40%, which allows an effectiveness energy 2 to 3 times larger than the current solar cells”, affirms Prof Worren. These new cells have semiconductor points in the shape of pyramid, which enables them to absorb more infra-red radiations.
“Thanks to this new type of cells, we will be able to build solar energy factories in the countries in the process of developments sunniest. With our latitudes, the most realistic use would be to cover our buildings with materials which would integrate solar cells”. On a world level, the installation of solar cell factories grows strongly due to the political implication. It is provided that their number triples from here 2010 compared to 2004. “In Norway if one covers 0,3% of the country with solar cell factories, we could support the overall consumption of energy in the country. An alternative would be to produce 1% of the consumption of electricity in Norway by using solar cells. This would correspond to 90.000 roofs of a surface of 100m2”.


LITTLE INTEREST SO FAR
“Theoretically, we might reach efficiencies of 60 per cent or higher. In practice we hope for 40 per cent efficiency at the start. Even at that level, the energy efficiency will be 2 to 3 times higher than today’s solar cells”,Worren says.
NTNU is the only institution in Norway where this kind of research is conducted. Worldwide, just a few groups are working on this new type of solar cell; otherwise, interest in the field has been limited.Worren says fossil fuels are to blame.
“I am convinced that a new generation of solar cells would have been available already, if not for cheap fossil energy”, she says.


QUANTUM DOTS

The new solar cells are based on what are called ‘quantum dots’. All solar cells use semiconductors to absorb sunlight, but today's cells are unable to absorb very much of the infrared heat radiation from the sun. The new solar cells being developed have pyramid-shaped semiconductor dots in addition to conventional semiconductors. These dots absorb a portion of the infrared light that the other parts of the solar cells do not capture.










The project uses new technologies and is partly financed by NTNU’s Nanolab. The longterm goal is to produce solar cells using this new technology.


BEAUTIFUL CELLS

“Using these kinds of solar cells, we could build solar cell power plants in sunny places in the developing world.At our latitudes, the most realistic use of this technology would be to cover buildings with aesthetic building elements that integrate solar cells", Worren explains. People would accept this approach if the cells were decorative enough,Worren says. “Solar cells can be beautiful, and a good alternative to decorative stone and window glass”, she says.



90,000 ROOFTOPS

On a worldwide basis, the installation of new solar cell plants (measured as the amount of energy produced) increased by 63 per cent from 2003 to 2004, with much of the increase due to political involvement. It is estimated that by 2010, the number of solar cell plants will have tripled compared to 2004. In Norway, solar cells are mainly used for mountain cottages and lighthouses, where it can be difficult to connect to the power grid.



“If we could cover 0.3 per cent of Norway’s land area with solar cell plants, we could produce 120 terawatt hours, which corresponds to our entire electricity consumption in 2002”, Worren says.
That means that it is physically possible to handle Norway’s total energy consumption with power from solar cells, but that is neither necessary nor desirable. One alternative could be to produce just one per cent of Norway's electricity consumption using solar cells. That would correspond to a solar cell area of some 90,000 roofs, each measuring 100 square metres”, she says.


SILICON SHORTAGES
Another factor that makes the production of more efficient solar cells interesting is the lack of raw materials for the current technology. Most solar cells have an active portion made of a thin wafer of silicon. The solar cell industry is currently experiencing a silicon shortage. The search for other ways to produce silicon has begun, but increased efficiency in silicon use will also be an important component of solar cell production.


About Researchers:
Turid Worren,
Department of Physics, NTNU
Tel: +47 73 59 18 42,
Email: turid.worren@ntnu.no



Funded:
The project uses new technologies and is partly financed by NTNU’s Nanolab.