Dr. Song Dengyuan is a prominent figure in the photovoltaic market, having made significant contributions to the development of N-type technology in China. In fact, Yingli Solar conducted research and development on N-type cells in 2009, marking the start of the technology's development history. Under Dr. Song's leadership, Yingli's team collaborated with the Energy Research Centre of the Netherlands (ECN) to jointly develop the high-efficiency N-type silicon bifacial PERT cell technology, which was named "Panda".

In 2010, "Panda" cells achieved a conversion efficiency of 18.5%, showcasing the high-efficiency advantages of N-type cells to the market. In June 2012, Dr. Song was invited to deliver a keynote speech at the 38th IEEE Photovoltaic Specialists Conference in Austin, marking the first time that a Chinese scientist had reported on the progress of large-scale industrialization of N-type bifacial cells at a globally authoritative PV conference.

“In 2013, Germany's Fraunhofer introduced the concept of Tunnel Oxide Passivated Contact (TOPCon) solar cell technology, but at that time, the market was not mature.” According to Dr. Song, the research and development of N-type TOPCon cells began to gain momentum in China around 2018. On August 8, 2018, Liu Yong founded DAS Solar and after conducting in-depth analyses of several technical routes, he concluded that TOPCon technology was the most promising next-generation photovoltaic technology.

In early 2022, Dr. Song was appointed as the Chief Technology Officer (CTO) of DAS Solar, where he assumed responsibility for the technical research and development of high-efficiency N-type cells and modules. Under Dr. Song's leadership, DAS Solar successfully developed TOPCon 3.0 technology, which further increased the average conversion efficiency of TOPCon cells in large-scale production to over 25.2%.

“Since establishment, DAS Solar has had a specific technological positioning, owing to Liu Yong's deep understanding of the connotation and extension of photovoltaic technology. In 2019, the company established the earliest domestic N-type TOPCon cell research and development manufacturing line - TOPCon 1.0. In 2020, cells based on TOPCon 1.0 Plus technology began mass production, achieving an efficiency of 23.5%. The efficiency of TOPCon 2.0 cells increased to over 24.6% in 2021. The average efficiency of TOPCon 3.0 cells surpassed 25.2% in 2022.” Dr. Song says.

“TOPCon 3.0 marks a significant milestone in DAS Solar's entire TOPCon innovation series, with the average conversion efficiency of cells increasing from 24.6% in TOPCon 2.0 to 25.2%, with the highest efficiency reaching 25.8%. DAS Solar has successfully developed the high-energy laser i-SE (industry-selected emitter) industrialization technology, which has independent intellectual property rights, and effectively reduces the recombination of photogenerated carriers on the front surface, while increasing the utilization of a short-wavelength spectrum. In addition, the company has also used the ut-polySi (Ultrathin Poly-Si) technology for the backsheet, which can effectively reduce the parasitic absorption of the back polycrystalline silicon layer on the long-wavelength spectrum, thus improving the utilization of the long-wavelength spectrum. The combination of these two technologies has overcome the bottleneck of the efficiency of TOPCon solar cells, resulting in a 40.6% increase in short-wavelength and 15.3% increase in long-wavelength quantum, and an average cell efficiency improvement of over 25.2%.”