Solar cells give ray of hope to Swiss scientists

The new cells mimic the process of photosynthesis in plants Keystone

The future of solar energy has been given a boost thanks to a new type of solar cell developed by the Federal Institute of Technology in Lausanne.

This content was published on July 31, 2003 - 14:59

The so-called nanocristalline solar cells have been shown to be much cheaper and just as effective as the silicon cells which have been used to make solar energy until now.

Thanks to new technology, the cost of making the nanocristalline cells could tumble by as much as 80 per cent.

Professor Michael Grätzel and his team at the Institute have been developing the cells since 1991.

The cells, which produce electricity by simulating the natural process of photosynthesis, have also just overcome a set of critical tests which could hold the key to their commercial success.

Heat test

The tests for the cells were devised to establish their durability and their ability to withstand heat.

This meant proving the cells would lose less than ten per cent of their performance after having been placed in a solar simulator and in an oven for 1,000 hours (amounting to nearly six weeks) at 80 degrees Celsius.

The experiment and its success made it into the pages of the scientific review, Nature Materials and Science. It’s also given hope to scientists looking for a cheaper way of producing solar energy.

Until now, solar cells have been made using semi-conductors, such as silicon, which convert light into electricity. But in order to be effective, only the purest silicon can be used, which results in high production costs and makes it very difficult to use on a large scale.

The head of development at Swiss Sustainable Systems, Tamas Sacsavay, has high hopes for the cells.

“It’s a brilliant project which opens new possibilities, notably in the development of large solar panels for which price plays a determining factor,” Sacsavay said.

Photosynthesis

To overcome this stumbling block, the Lausanne team was inspired by photosynthesis, a chemical reaction which green plants use to transform sunlight into “food” through chlorophyll pigments.

Before commercialisation, these nanocristalline cells have to pass further tests to see if larger cells would also be successful.

It is estimated that developers will need to spend another two years to refine the product and a further year to produce it commercially.

There’s no shortage of uses. These cells could be used to drive small computers as well as being used as mini electricity generators to be used in an African village.

swissinfo, Jean-Didier Revoin (translation: Faryal Mirza)

In brief

Conventional solar cells are usually made from silicon – as they have to be of a certain grade, that often makes them very expensive.

Michael Grätzel and his team have developed new solar cells, which generate electricity using photosynthesis as a model.

The new cells have recently passed a test which could see them on the market within at least four years.

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