Sunlight is the most abundant energy source on the planet and is currently used by a huge number of silicon solar panels on rooftops and fields around the world. However, a new generation of panels are emerging, using a class of materials called perovskites. This is thinner, lighter, less rigid and can produce more power.
This technology means that solar panels can be integrated into new locations such as car roofs, street lights, and even windows. It could also mean an increase in solar power without spending much land on solar farms.
How does it work?
Perovskite solar panels can come with or without silicon. The most common type is a “tandem” cell, with a layer of perovskite over silicon.
The combination of the two materials maximizes the absorption of light to generate electricity. Perovskite is particularly effective at absorbing high-energy “blue” light, while silicon is more effective by using lower-energy “red” light.
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Oxford PV, the UK developer of Perovskite solar panels, said its tandem cells can generate 20% of their power from panels of a particular size, and more profits are expected as the technology matures.
Other types of panels use perovskite on their own. This is 200-300 times thinner than the silicon of solar cells. Multiple layers of perovskite can be used, each tuned to absorb light of different wavelengths. This type of panel is much more flexible than a silicone panel.
According to Oxford PV CEO David Ward, perovskite-only cells “wrap in a roll” and the tandem cells can be slightly tortuously “up the aircraft’s wing surface.”
What are the advantages and disadvantages?
Tandem solar panels are more efficient than silicon, allowing them to generate the same amount of energy from smaller spaces and free up land for other uses. On the other hand, the thinness and flexibility of perovskite-only panels means they can be deployed on a variety of surfaces, including bus shelters, facade construction, and electric vehicle roofs. If designed to be translucent, it can be added to the windows while experiencing sunlight.
The manufacturing process is also relatively simple and energy efficient. Perovskite solutions can be sprayed onto surfaces like ink. It is then heated to crystallize at a temperature much lower than required to refine the silicon.
However, perovskites are also vulnerable to deterioration. “When (perovskite) crystallizes, there are some gaps and solvents there, meaning they are susceptible to oxygen and humidity,” explains Professor Ravi Silva, director of the Institute of Advanced Technology at Surrey, which studies perovskite cells.
You can add protective casings, but they don’t last as long as they are silicon panels. The Oxford PV tandem panels last 10 years. The company aims to source it in 2027 in 2020. In contrast, silicon panels usually have a lifespan of 25 years.
The two most common perovskites used to generate solar cells both contain lead and toxic metals that can penetrate the environment and cause health problems, but lead-free alternatives have been developed.
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Does it save the planet?
If the world reaches net zero by 2050, if one fifth of the world’s energy needs to be supplied by solar, the International Energy Agency is predicted. Perovskite cells can speed up along it.
Last year, solar panels produced 2,131 terawatt hours of electricity. Currently, tandem panels are 20% stronger than traditional panels, converting them to 426th of electricity, roughly the same as Germany’s total electricity production. And that’s before the potential additional capacity that arises from the additional solar panels installed in new locations.
The cost of solar panel land is an important limiting factor in a country with high population density. Both Korea and Japan are developing perovskite panels that can be integrated into urban environments.
However, it doesn’t happen immediately if cheap silicon panels dominate the market and use stronger cells to replace them.
Have you arrived already?
Some companies have begun selling perovskite solar panels as part of their pilot programs before mass production.
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Last year, Oxford University spin-out Oxford PV announced that it had said it was the first commercial shipment of tandem panels manufactured at a German factory for US-based customers.
The company’s current panel is 25% efficient. This means delivering 25% of the solar energy to electricity. According to FT research, this figure tends to surpass standard silicon panels, and to around 20-23%. We aim to produce large-scale production starting in 2027.
China’s GCL perovskite, part of the energy giant GCL, says it plans to “commerce” its tandem panels to begin next year.
Perovskite-only panels are in the stages of development, not commercial production. Martin Wang, director of GCL Perovskite, says the technology cannot currently compete with the efficiency and low cost of traditional solar panels.
Who are the winners and the losers?
Their dominance in the manufacture of silicon panels means that they already hold a central position in the solar supply chain, which means that Chinese companies will benefit significantly.
Other worlds have risks from supply chains being almost entirely dependent on China. This is partly due to geopolitical tensions, but Jana Frisico, head of solar supply chain research at Wood Mackenzie, warns of other events that could cause similar supply chain disruptions.
Who is investing in it?
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Established solar energy companies are looking to diversify into perovskite technology as well as startups such as Oxford PV. In China, Trinasolar, Longi and Jinkosolar are all investing in the production of tandem solar panels.
Korean Q Cells are planning to mass-produce tandem panels by 2027, and the Japanese government has announced a $167 million subsidy to three companies that will mass-produce perovskite solar cells over the next five years.
This will help fund gigawatt-scale plants by 2030, with subsidies worth up to $1 billion worth of Japanese Sekisui Chemicals above.
