Solar Energy Breakthrough Could Reduce Need for Solar Farms

Scientists at Oxford University Physics Department have developed a revolutionary approach that could generate increasing amounts of solar electricity without silicon-based solar panels. Instead, their innovation works by coating a new power-generating material onto the surfaces of everyday objects like rucksacks, cars, and mobile phones.

Their new light-absorbing material is, for the first time, thin and flexible enough to apply to the surface of almost any building or common object. Using a pioneering technique developed in Oxford, which stacks multiple light-absorbing layers into one solar cell, they have harnessed a wider range of the light spectrum, allowing more power to be generated from the same amount of sunlight.

This ultra-thin material using the so-called multi-junction approach has now been independently certified to deliver over 27% energy efficiency, for the first time matching the performance of traditional, single-layer, energy-generating materials known as silicon photovoltaics. Japan’s National Institute of Advanced Industrial Science and Technology (AIST), gave its certification before publication of the researchers’ scientific study later this year.

“During just five years experimenting with our stacking or multi-junction approach we have raised power conversion efficiency from around 6% to over 27%, close to the limits of what single-layer photovoltaics can achieve today,” said Dr Shuaifeng Hu, Post Doctoral Fellow at Oxford University Physics. “We believe that, over time, this approach could enable the photovoltaic devices to achieve far greater efficiencies, exceeding 45%.”

This compares with around 22% energy efficiency from solar panels today (meaning they convert around 22% of the energy in sunlight). Still, the versatility of the new ultra-thin and flexible material is also key. It is almost 150 times thinner than a silicon wafer at just over one micron thick. Unlike existing photovoltaics, generally applied to silicon panels, this can be applied to almost any surface.

“By using new materials that can be applied as a coating, we’ve shown we can replicate and out-perform silicon whilst also gaining flexibility. This is important because it promises more solar power without the need for so many silicon-based panels or specially-built solar farms,” said Dr Junke Wang, Marie Skłodowska Curie Actions Postdoc Fellow at Oxford University Physics.

The researchers believe their approach will continue to reduce the cost of solar and also make it the most sustainable form of renewable energy. Since 2010, the global average cost of solar electricity has fallen by almost 90%, making it almost a third cheaper than that generated from fossil fuels. Innovations promise additional cost savings as new materials, like thin-film perovskite, reduce the need for silicon panels and purpose-built solar farms.

“We can envisage perovskite coatings being applied to broader types of surfaces to generate cheap solar power, such as the roof of cars and buildings and even the backs of mobile phones. If more solar energy can be generated in this way, we can foresee less need in the longer term to use silicon panels or build more and more solar farms” Dr Wang added.

Researchers at Oxford University are among 40 scientists working on photovoltaics, particularly using thin-film perovskite. Their work has commercial potential and is being applied in the utilities, construction, and car manufacturing industries. Oxford PV, a UK company, has started large-scale manufacturing of perovskite tandem solar cells in Germany.

“We originally looked at UK sites to start manufacturing but the government has yet to match the fiscal and commercial incentives on offer in other parts of Europe and the United States,” Professor Snaith said. “Thus far the UK has thought about solar energy purely in terms of building new solar farms, but the real growth will come from commercializing innovations – we very much hope that the newly-created British Energy will direct its attention to this, Professor Snaith said.”

He added that UK scientists are developing solar materials and techniques to create a sustainable and affordable industry for solar energy generation. Professor Snaith believes the UK is leading the way in this green economy, but requires new incentives and a better manufacturing pathway.