A recently introduced, more efficient kind of solar cell may hold the key to the future of solar energy. They can produce panels with useful efficiency rates significantly higher than 30% since they are made of a family of crystalline minerals known as perovskites.
The idea that the Earth receives enough sunshine in a single hour to cover the world’s power needs for a year is widely held and accurate. Arrays of solar panels are already converting some of that sunlight into power; by the end of 2023, these panels had covered about 10,000 square kilometers of the Earth’s surface, generating 1,600 terawatt-hours of electricity, or roughly 6% of the total amount created globally.
Approximately every three years, the installed solar capacity has doubled. This is occurring as a result of fierce competition among Chinese companies who, with government assistance, have taken control of the market as silicon-based solar cells used in panels have become more affordable. Meanwhile, scientists have discovered methods to improve the cells’ ability to absorb solar energy. Compared to the 6% efficiency attained when the first viable solar cells were developed in the 1950s at Bell Laboratories in New Jersey, and were so costly that they were primarily used to power satellites, modern solar panels run at 22–24% efficiency rates.
However, the majority of procedures have limitations. A silicon solar cell’s highest theoretical efficiency, or the percentage of solar energy converted to electrical power, is about 29%. Heat is the result of the remaining solar energy being lost. Only in a lab setting is this theoretical maximum feasible. Furthermore, the overall efficiency of solar panels made up of densely packed cells is unlikely to exceed 26%. This is partially due to the fact that the gaps between cells and other panel components, like the frame, don’t help generate electricity. Energy losses in the cables that link the cells are also unavoidable.
Conventional solar cells usually consist of two ultra-pure silicon layers that have been doped with an additive to enable them to function as either conductors or insulators. Electrons get enough energy from absorbing light to leap over the layer junction and create an electric current. While other semiconductors are capable of doing the same, none can match silicon’s affordability due to its low cost of production from sand.
Calcium titanium oxide is a mineral that was the first perovskite. Named for the Russian mineralogist Count Lev Perovski, it was found in 1839. Since then, the word has evolved into a general term for materials with comparable crystalline structures. In addition to being effective at absorbing solar energy, perovskites can also be produced inexpensively from readily available materials, such as various metals and halogens like iodine, chlorine, and bromide. This is one of the factors that makes them so appealing to researchers as a silicon substitute.
Oxford PV, a British company headquartered close to the university that bears the same name as its research activities, is one of the pioneers in the development of perovskite panels. The company has created what are known as tandem cells, which are made out of a conventional silicon substrate with a thin coating of perovskite on top. Together, the two materials are supposed to be able to collect more energy from sunlight than they could separately. According to Chris Case, the company’s chief technical officer, this is accomplished by adjusting the perovskite layer above to absorb light from the blue end of the spectrum while the silicon layer underneath mops up the wavelengths at the red end.
It should come as no surprise that Chinese suppliers are actively investigating perovskites. At 34.6%, the lab-based perovskite tandem cell holds the current world record. A major Chinese producer of solar cells, LONGi Green Energy Technology, made this assertion in June. In October 2023, it started developing methods for producing the cells in large quantities. According to the company, it has also obtained a 30.1% level from a commercial-sized prototype panel. LONGi has not yet disclosed the start date of production.
source : Economist
