Introduction: The End of "Either-Or" in Solar Tech
For years, the photovoltaic industry has been trapped in a binary narrative: TOPCon versus Heterojunction (HJT) versus Back Contact (BC). Each technology had its loyalists, each faced its own bottlenecks. As traditional crystalline silicon cells approach their theoretical efficiency limit, the industry has struggled with diminishing returns on innovation and high-stakes technical bets. But a new paradigm has emerged in 2026-one defined not by rivalry, but by strategic fusion.
The Flagship of Fusion: THBC Technology
Leading this shift is Trina Solar's breakthrough THBC (TOPCon-compatible Hybrid Back-Contact) cell. In late April 2026, Trina announced that its independently developed THBC cell achieved a certified efficiency of 28.00% in a 210R industrial-size wafer - the first time a large-area crystalline silicon cell has surpassed the 28% threshold.THBC is not a simple recombination of existing technologies. As Trina's technical team explained, it deeply integrates three major advantages: the superior passivation contact of TOPCon, the efficient passivation capability of HJT's amorphous silicon, and the front-side grid-free design of BC technology. The result is a "low-temperature hybrid passivation structure" that solves the dual problems of insufficient passivation and conductivity degradation found in earlier TBC designs. Importantly, THBC is designed for industrial scalability. It follows a TOPCon-compatible route, requiring only the addition of localized PECVD and laser equipment to upgrade existing TOPCon production lines - a vastly lower capital investment than building new HJT fabs from scratch.
Complementary Breakthrough: HBC Sets a New Record
Just weeks after Trina's announcement, JA Solar and Golden Stone Energy jointly unveiled their own fusion masterpiece: an HBC (Hybrid BC) cell that achieved a certified efficiency of 28.2% from TÜV Rheinland. HBC builds on the standard BC cell foundation by combining traditional heterojunction passivation structures with tunneling/polysilicon architectures, achieving what the companies describe as the "perfect fusion" of TOPCon, HJT, and BC into a single cell. The fact that this breakthrough came from the very first batch of HBC production cells demonstrates not only the route's efficiency potential but also its robust engineering validation for mass production. Together, THBC and HBC have shattered the illusion that the industry must choose between technology camps.
A "Passivating Pinhole" Revolution: Rewriting TOPCon's Blueprint
Even as fusion technologies take center stage, fundamental scientific discoveries continue to push mainstream TOPCon forward. A research team led by Professor Chen Jianhui at Hebei University, in collaboration with DAS Solar and the Forschungszentrum Jülich in Germany, published a landmark study in Nature Communications identifying a phenomenon they named "Passivating Pinholes".
For nearly a decade, the photovoltaic community faced a paradox: TOPCon cells rely on an ultra-thin silicon oxide layer for passivation and carrier transport, yet the high-temperature fabrication process inevitably creates "pinholes" - tiny local defects in the oxide. Conventional wisdom held that these pinholes must degrade passivation performance. But the research revealed that not all pinholes are created equal. The team discovered, at atomic-scale resolution, that pinholes exhibit a "dual face": one type indeed causes recombination losses, while another type not only facilitates efficient carrier transport but also maintains excellent passivation characteristics. This discovery provides the long-sought experimental evidence explaining why TOPCon's open-circuit voltage approaches that of HJT, and why TOPCon's theoretical efficiency limit can actually surpass HJT. The finding offers a scientific roadmap for further efficiency improvements in the industry's dominant technology, which accounted for 87% of the global crystalline silicon market in 2025.Outlook: A New Logic for Solar Innovation
What emerges from these developments is a fundamental shift in the logic of photovoltaic innovation. The industry has moved beyond the era of zero-sum technology competitions. THBC and HBC demonstrate that hybrid architectures can capture the best of multiple technologies while leveraging existing manufacturing footprints. The "Passivating Pinholes" discovery shows that even mature technologies like TOPCon still hold profound mysteries - and significant headroom for improvement. And the rapid scaling of perovskite tandems signals that the march toward 30% and beyond is no longer a theoretical exercise but an industrial reality. As Trina Solar executive Ni Lili articulated, the future lies not in a single technology dominating all scenarios, but in "TOPCon+THBC dual-drive strategy" that assigns the right solution to the right application - bifacial TOPCon for large utility plants and THBC for high-value rooftop distributed generation.For an industry long obsessed with binary rivalries, the most powerful innovation may simply be realizing that the best path forward is not a choice between technologies - but their strategic, intelligent fusion.
