Breakthrough in solar cells will provide cheap energy

Technical advance based on edible salt overcomes need to use toxic agents

A breakthrough in the production of solar cells will make the next generation of solar panels cheaper and safer, and promises to accelerate the development of solar energy over the next decade, scientists said.

A technical advance based on an edible salt used in the manufacture of tofu could revolutionise the production of future solar panels to make them less expensive, more flexible and easier to use than the current models seen on roofs.

Researchers believe they have found a way of overcoming one of the most serious limitations of the next generation of solar panels, which are based on toxic cadmium chloride, by simply adding magnesium chloride, an abundant salt found in seawater.

A study has shown that the solar cells produced with magnesium chloride - which is also found in bath salts as well as used to coagulate soya milk into tofu - work just as efficiently as conventional cadmium cells but at a fraction of the cost and with much lower toxicity.

"Magnesium chloride is incredibly low-cost and it's simply recovered from seawater. It's used to de-ice roads in winter and it's completely harmless and non-toxic. We've managed to replace a highly expensive, toxic material with one that's completely benign and low cost," Dr Major said.

About 90 percent of the solar panels currently in use are made of photovoltaic cells composed of silicon semiconductors, which convert sunlight directly into electricity.

However, silicon is not good at absorbing sunlight which is why the next generation of PV cells will be based on a thin coating of cadmium telluride, which absorbs sunlight so well that it only needs to be about one hundredth of the thickness of silicon.

However, although cadmium telluride is seen as the future for solar energy, it is potentially dangerous after it is "activated" with cadmium chloride, a critical step in the manufacturing process that raises the efficiency of converting sunlight to electricity from about two per cent to 15 percent or more.

The Liverpool team attempted to find an alternative to cadmium chloride in the activation step and discovered that it could be done just as well with magnesium chloride, which they sprayed onto a test sample of cadmium telluride with a model aircraft spray gun they bought for £49.99, Dr Major said.

In a study, the researchers demonstrated that the efficiency of the resulting photovoltaic cells made from cadmium telluride and magnesium chloride were on a par with commercial cadmium telluride cells that had been activated with toxic cadmium chloride.

- The Independent