Recently, the latest certification report from the U.S. National Renewable Energy Laboratory (NREL) showed that the efficiency of the crystalline silicon-perovskite stacked cell independently developed by Longi Green Energy reached 33.9%, once again setting a world record.

This world record breakthrough provides significant empirical data to demonstrate the efficiency advantages of crystalline silicon-perovskite tandem cells compared to single-junction cells. This also marks that LONGi Green Energy has become the world’s number one in the two major fields of silicon-based single-junction cells and silicon-based stacked cells that are the most popular in the global photovoltaic industry.

Li Zhenguo, founder and president of LONGi Green Energy, said that the photoelectric conversion efficiency of solar cells is a key indicator and benchmark for evaluating the potential of photovoltaic technology. As a mainstream battery technology occupying more than 90% of the market share, the conversion efficiency of crystalline silicon single-junction cells continues to improve, getting closer and closer to its theoretical efficiency limit of 29.4%. The theoretical efficiency limit of crystalline silicon-perovskite stacked cells can reach 43%, and it is recognized as the mainstream technical solution to break through the efficiency limit of single crystalline silicon cells. The emergence of crystalline silicon-perovskite stacked cell technology has opened up a new track for the development of next-generation high-efficiency solar cell technology.

According to Dr. Xu Xixiang, chief scientist of LONGi Green Energy and deputy director of Academia Sinica, the bottom cell of the stacked cell that set a new record is partly based on crystalline silicon heterojunction technology, and the top cell uses perovskite. This is because heterojunction technology is a low-temperature process, which is conducive to the growth of perovskite films; on the other hand, although perovskites can also be stacked with technologies such as TOPCon or even PERC, the conversion efficiency will decrease when stacked at both ends. It is 2-3 percentage points lower than the heterojunction stack.

He Bo, technical director of Longi Green Energy Central Research Institute, added that the company launched the heterojunction battery project in February 2021, and then began research and development of stacked batteries. Several important nodes in the past include achieving a stack conversion efficiency of 23% in June 2021, reaching 29.55% at the end of last year, and exceeding 31.8% and 33.5% in May and June this year, until this time it achieved an efficiency of 33.9% . At the same time, LONGi’s crystalline silicon-perovskite stacked cells aim to achieve a conversion efficiency of 35% in the second half of next year.

Jiang Hua, deputy secretary-general of the China Photovoltaic Industry Association, said that once this high-efficiency battery technology is truly mass-produced, it will promote a significant reduction in the cost of photovoltaic power generation compared with before, which will be absolutely crucial to promoting the growth of the photovoltaic market in my country and even the world. benefits. The growth of the photovoltaic market will also drive the entire energy revolution and energy transformation.

Regarding the industrialization process of perovskite batteries, He Bo said that there are two issues that need to be solved. One is to find suitable application scenarios, and the other is to solve the problem of reliability. The industry predicts that it may take 8 to 10 years to achieve mass production of crystalline silicon-perovskite stacked cells. Longi Green Energy may be one step faster, about 7 years.

Sobi Photovoltaic Network believes that perovskite, as a new type of high-efficiency photovoltaic cell technology, has obvious advantages such as easy availability of raw materials, low investment costs, and high stacking efficiency potential, and provides an effective way to achieve high-efficiency stacked cells and components. . However, to achieve large-scale production and application, a series of technical problems such as fast decay, short life, and difficulty in achieving large size need to be continuously solved and improved.

Currently, two-terminal stacked cells that combine perovskite technology with crystalline silicon heterojunction technology are one of the routes that are likely to see results in the short term. Crystalline silicon-perovskite stacked cells still face huge challenges from the laboratory to industrialization. It requires integrated innovation through ecological chain integration and pioneering and innovation for different application scenarios in order to have the conditions for large-scale commercial promotion. Further Promote the industrial process of China’s crystalline silicon-perovskite stacked cells.

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