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 millions of roofs across Britain.
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.
“We certainly believe it’s going to make a big change to the costs of these devices. The cost of solar is going to match fossil fuels eventually but this is going to get us there quicker,” said Jon Major of the University of Liverpool, who led the research.
“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 per cent 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.
Solar panels around the world
Solar panels around the world
Photovoltaic solar panels on the roof of the Chint Group office building in Hangzhou, Zhejiang Province, China
On 13 October 2011 France launched its largest-ever solar energy farm, with an array of panels spread over about 200 hectares (500 acres) in the mountainous southern Alpes-de-Haute-Provence region in Les Mees. With a production capacity of 90 megawatts, the vast photovoltaic park features nearly 113,000 solar panels and was built at a cost of 110 million euros ($137 million)
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Solar Panels, Photovoltaic array at the University of New Mexico, Taos campus, USA
Large solar panels are seen in a solar power plant in Hami, northwest China's Xinjiang Uygur Autonomous region
Some of the panels of France's biggest photovoltaic power station in Bordeaux. This station, with its 60.000 panels set on the parking of the Bordeaux-Lac international fair was launched in May 2012
Built on a former NATO base, this is one of the most important photovoltaic plant in France, located at Crucey near Chartres. It was developed by electricity provider EDF (Electricite de France)
The project manager from solar century walks between lines of solar panels erected at Weighbridge, Wheal Jane, Baldhu near Truro, England. Launched in 2011, this was the first solar farm in the South West and biggest in the UK
A worker climbs over a solar panel at a solar factory in Longyou county, Zhejiang province
Workers install solar panels containing photovoltaic cells at the new Solarpark Eggersdorf solar park in 2012 near Muencheberg, Germany. The park, which was being built by German solar energy operator juwi Solar GmbH and contains 85,000 solar modules and is one of many similar projects in eastern Germany
In 2010 homeowners had solar panels installed this month as growing numbers of people and companies look to cash in on the Government's renewable energy scheme
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In 2009 a solar panel system was installed on the roof of a business building in Gainesville, Florida. Gainesville became the first city in the nation to have a solar feed-in tariff ordinance which meant owners of new solar photovoltaic systems were eligible to receive 32 cents per kilowatt hour of electricity produced by the system over the next 20 years
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 per cent 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 published in the journal Nature, 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.
“We have to apply cadmium chloride in a fume cupboard in the lab, but we created solar cells using the new method on a bench with a spray gun bought from a model shop,” Dr Major said.
“Cadmium chloride is toxic and expensive, and we no longer need to use it. Replacing it with a naturally occurring substance could save the industry a vast amount of money and reduce the overall cost for generating power from solar,” he said.
It is not possible to estimate how much cheaper the new solar cells will be, Dr Major said, but magnesium chloride is about one per cent of the cost of cadmium chloride. In addition, waste disposal will be far easier and cheaper with a product based on a non-toxic salt, he said.
Asked why the solar power industry had not thought of using magnesium chloride before, Dr Major said: “We genuinely don’t know. The only reason we can suggest is that cadmium chloride works well so it may be a case of ‘if it’s not broke, why is there a need to fix it?’”
Jeremy Leggett, chairman of the renewable energy firm Solarcentury, said that the development is exciting because it promises to make an already competitive industry even more competitive with conventional sources of energy, such as fossil fuels.
“Their costs are coming down so fast that they are already knocking the business models of utilities into what some analysts call a ‘death spiral’. Imagine, then, what will happen if developments such as the one described in the new research come to market,” Dr Leggett said.Reuse content