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Breakthrough in Photovoltaic Manufacturing


Researchers at Liverpool University have found a way to greatly reduce the cost and toxicity of manufacturing the next generation of solar panels. The key is substituting one chemical for another. As the BBC report explains:

Dr John Major, who led the research said that his team’s work might be the development that brings the cost down to the level of fossil fuel,” he told BBC News.More than 90% of the solar cells are made from silicon. Around 7% are made from a material called cadmium telluride. The cadmium telluride cells are thinner than silicon and these are popular because they are also lighter and cheaper.

Toxic ingredient

They have the drawback that a toxic chemical, cadmium chloride, is needed to manufacture them. Cadmium chloride is also expensive.

A significant proportion of the manufacturing cost of cadmium telluride cells is to protect the workforce from toxins and to dispose of contaminated waste products safely, according to the research team.

The Independent has some more of the details:

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.

One of the problems new technologies have in the process of replacing established but less desirable ones is the time factor. Technologies that have been around for a while have had time for refining and incorporation of efficiencies from years of practical experience. They are at the end of a long learning curve. Using a cheaper and less toxic chemical is one of those incremental steps in getting photovoltaics to be more competitive. The price can only keep going down.

We can see a similar phenomenon at work in the auto industry. The gasoline powered internal combustion engine has been around for decades. It’s now being challenged by electric and fuel cell alternatives, but they have a lot of catching up to do. As with the solar panels above, advances in materials sciences and chemistry could make a big difference. Electric battery improvements in capacity, weight, expense, and charging time are closing the gap. Fuel cells are lagging a bit, but advances in generating and storing hydrogen for fuel could change that as well.

Cadmium telluride cells have better performance than silicon, but limited and costly supplies of tellurium are still a potential bottleneck. If this new process succeeds, that will help drive the search to find substitutes for tellurium as well. We haven’t quite gotten to the Douglas-Martin Sunscreenyet, but we’re closing in.