For more than a decade, few individuals have been as closely intertwined with the rise of N-type technology as DAS Solar's Chief Technology Officer, Dr. Dengyuan Song. From the early days of laboratory research to today's era of gigawatt-scale commercial deployment, his professional journey mirrors the transformation of N-type technology from a niche concept into the dominant force shaping the global solar industry.
A Return Home That Redirected an Industry
In 2009, after years of research at the University of New South Wales under PV pioneer Professor Martin Green, Dr. Song returned to China to join Yingli Solar as CTO. That same year, Yingli established a national key laboratory for PV materials and technology, placing N-type silicon cells at the center of its long-term research strategy.
At that time, only two companies globally—SunPower and Sanyo—had committed to N-type development. Their technologies demonstrated extraordinary efficiency, but high costs and manufacturing complexity kept N-type products out of the mainstream market. Dr. Song joined with a clear ambition: to bring N-type technology out of specialist labs and into mass production.
The First Breakthrough: The PANDA Cell
The pivotal moment arrived with the launch of Yingli's PANDA project in 2009. Working with the Dutch Energy Research Centre (ECN), Yingli set out to industrialize N-type PERT cells on an unprecedented scale.
The technical challenges were profound. There were no suppliers capable of producing large-area N-type wafers, nor were there furnaces designed for N-type ingot pulling. Many core pieces of process equipment did not yet exist. The project team needed to design key processes from scratch, introducing new manufacturing sequences, new passivation technologies, and new metallization concepts.
Despite the obstacles, the first PANDA cell reached an efficiency of 18% within months, already outperforming mainstream P-type cells at the time. When the technology was transferred to production, the efficiency quickly rose to 18.5%, and China became the world's third country capable of manufacturing N-type cells at scale. By 2012, the PANDA technology achieved a Fraunhofer-certified efficiency of 19.49%, firmly establishing N-type as a commercially viable technology.
From Pilot Line to Global Validation
PANDA's performance was soon validated at the system level. In 2016, a 50 MW installation in Shanxi, then the world's largest N-type bifacial plant, demonstrated significantly higher real-world energy yield than neighboring stations using conventional P-type technology. Independent monitoring later confirmed that the N-type system delivered up to 19% higher monthly output during its initial operation period.
This marked the first time that a large-scale project conclusively proved the long-term power-generation advantage of N-type designs, accelerating global interest in high-efficiency cell architectures.
The Evolution to TOPCon
As research progressed internationally, the industry saw a major milestone in 2013 when Fraunhofer ISE introduced TOPCon, an evolution of the PERT concept with a polysilicon passivated contact. TOPCon maintained the core strengths of N-type architectures while addressing bottlenecks in passivation, carrier selectivity, and manufacturability.
The most important factor, however, was its compatibility: TOPCon could be integrated into existing PERC and PERT production environments with far less structural disruption than other next-generation technologies. This compatibility later became decisive in enabling TOPCon to scale faster and more efficiently than alternative concepts.
The pace of adoption accelerated dramatically after 2020. By 2022, more than thirty manufacturers had committed to TOPCon, making it the fastest-growing high-efficiency cell technology in the world.
A New Chapter: Joining DAS Solar
In 2022, Dr. Song joined DAS Solar as Chief Technology Officer, bringing decades of experience to a company that had already identified N-type as the future of photovoltaic technology. Since 2019, DAS Solar had been building one of the earliest TOPCon pilot lines in China and refining the technology generation by generation, from TOPCon 1.0 to the latest TOPCon 5.0.
Under his leadership, DAS Solar's TOPCon 5.0 technology has achieved remarkable progress, including mass-production efficiencies of 27% and an open-circuit voltage of 746 mV. These gains were made possible through innovations in back-contact microstructures, precision laser processing, advanced metalation, hybrid passivation materials, and durability-enhancing stacked films. Collectively, these advances strengthened both the electrical performance and long-term reliability of the technology, consolidating DAS Solar's position at the forefront of the N-type market.
Beyond TOPCon: DAS Solar's DBC Technology Line
Dr. Song's work at DAS Solar extends far beyond incremental improvements. Beginning in 2020, the company initiated development of its proprietary DBC (DAON-BC) architecture, merging its SiO₂/Poly-Si passivated contact with a back-contact structure. This innovation represented a new direction for N-type development and offered a pathway toward even higher performance.
DAS Solar has now advanced this platform to DBC 3.0 Plus. Independent laboratories have certified cell efficiencies of up to 27.77%, while mass-production averages exceed 27.5%. The resulting modules surpass 665 W with conversion efficiencies of 24.6%. These achievements place DBC among the most competitive next-generation cell technologies currently in development anywhere in the world.
The Arrival of the N-Type Era
By 2024, the global solar industry had decisively entered what many now describe as the N-type era. TOPCon alone accounted for more than 70% of global cell production. Industry forecasts suggest that N-type technologies may reach 85% market share by 2025, reflecting their strong performance across different climates and installation types.
The shift has been driven not only by advances in efficiency, but also by demonstrably higher long-term output, superior durability, and more stable performance in varying environmental conditions. The cumulative effect of these attributes has made N-type architectures the preferred choice for utility and distributed projects worldwide.
Looking ahead, Dr. Song believes that the future of high-efficiency photovoltaics will be shaped by the continued evolution of N-type concepts, including tandem structures and advanced back-contact designs. Even so, he sees TOPCon as the industrial foundation upon which many of these innovations will be built. From PANDA to TOPCon 5.0 to DBC 3.0 Plus, Dr. Song's personal journey reflects the trajectory of the global PV sector: faster, more efficient, more reliable, and increasingly central to the world's clean-energy transition.
