The Three Pillars of Mainstream N-type Technology
Song emphasized three critical factors for determining the mainstream technology in the PV sector: LCOE, cell efficiency, and industrial ecosystem.
“The ecosystem is paramount,” Song explained. “It determines the speed of cost reduction, as energy products must be economically viable to replace traditional energy sources.” While critical, efficiency serves as a means to reduce costs rather than an end goal. Song noted that even though gallium arsenide (GaAs) cells boast efficiencies nearing 50%, their high cost makes them unsuitable for terrestrial applications. In addition, low LCOE is also essential for large-scale replacement of fossil fuels, solidifying the pathway for renewable energy adoption.
TOPCon’s Technological Advantages and Future Dominance
TOPCon technology has rapidly gained market share, climbing from 23% in 2023 to an estimated 75% in 2024, with projections exceeding 80% in 2025, according to the China Photovoltaic Industry Development Roadmap. This ascent is attributed to TOPCon’s structural advantages, particularly its advanced passivation technology, which significantly improves efficiency and reduces costs.
“Solar cell efficiency and cost depend heavily on the passivation structure,” Song explained. “TOPCon’s comprehensive passivation enables full-area optimization, overcoming the limitations of partial passivation seen in PERC cells.” By comparison, BC technology primarily focuses on electrode configurations, making its performance contingent on the underlying passivation method, whether TOPCon or HJT.
Song studied historical trends and concluded that each solar cell technology follows a 10-year life cycle, resembling a bell curve. This trajectory starts with a market share of 20%, peaks at 70-80%, and then tapers to around 10% over the next five years.
Based on this model, Song predicted that TOPCon will dominate the market for the next 3-5 years, driven by its unparalleled passivation capabilities, high efficiency, and scalability. “Crystalline silicon’s high stability, non-toxic nature, and abundant resources ensure it will remain the dominant platform for at least the next decade,” Song added.
Charting a Path to Improving Efficiency Gains
TOPCon technology currently achieves a laboratory efficiency record of 27.3%, with its theoretical limit at 29.4%. To validate the potential of TOPCon technology, Song analyzed the theoretical and laboratory efficiencies of 26 different cell types. His findings revealed that crystalline silicon cells are by far the closest to their theoretical efficiency, with a mere 2.11% gap.
Song outlined clear steps for further improvement, emphasizing the importance of minimizing surface recombination and enhancing carrier lifetimes. A simulation by Professor Martin Green identified two key factors for increasing efficiency to 28%. First of all, the carrier lifetimes should exceed 4.5 ms. In the meantime, the surface recombination currents should be below 5.6 fA/cm².
In fact, the carrier lifetime in current silicon materials can fully meet the requirements, especially with full-area contact passivation. However, achieving a recombination current of 5.6 fA remains very challenging. The best current level is approximately 8 fA. Therefore, to continue improving efficiency, surface recombination becomes the most critical factor.
Song expressed confidence that these milestones are achievable, paving the way for continued efficiency improvements in the future.
DAS Solar’s Vision: One Core, Three Branches
As one of the fastest-growing PV companies globally, DAS Solar adheres to its “one core, three branches” strategy. With TOPCon technology serves as the foundational platform, it employs DBC, TSiP, and SFOS as three supporting technologies.
Currently, DAS Solar’s TOPCon technology is in its 4.5th generation, achieving world-class performance metrics, including an open-circuit voltage of 745 mV and a mass production efficiency of 26.7%. Meanwhile, the company’s first-generation DBC products deliver efficiencies of 26.5%, and its perovskite tandem cells, developed in collaboration with universities, have reached 33.2% in laboratory settings.
Looking ahead, DAS Solar aims to surpass 40% cell efficiency by leveraging its robust technology strength and fostering advancements across multiple technologies. “With TOPCon technology as the core, we are committed to pushing the boundaries of PV technology, achieving new levels of efficiency, and driving the global energy transition,” Song concluded.
