From TOPCon to THBC: Trinasolar’s Next Step in High-Efficiency Solar Technology

Over the past few years, TOPCon has become one of the defining technologies of the solar industry. It has enabled higher cell efficiencies, stronger bifacial performance, and a mature manufacturing platform capable of supporting the rapid global expansion of high-power PV modules.

Yet the industry has entered a more demanding phase. As TOPCon moves deeper into mass production, incremental efficiency gains become harder to capture. The next generation of crystalline silicon technology must therefore answer a broader question: how to combine higher efficiency with cost discipline, manufacturing compatibility, field reliability and application-specific customer value.

This is the context in which Trinasolar has introduced THBC.

THBC is not a departure from TOPCon. It is a deliberate upgrade built on TOPCon’s manufacturing scale and industrial maturity. Rather than chasing a laboratory record alone, Trinasolar is seeking to translate next-generation cell efficiency into module power, system value and commercial differentiation.

What THBC is: a structural reinvention

THBC stands for TOPCon-compatible Hybrid Back-Contact Cell. The name captures both the technology’s ambition and its industrial logic.

At its core, THBC combines three major PV technology streams. TOPCon provides the passivated-contact structure and large-scale manufacturing base. HJT contributes high-quality amorphous silicon passivation. BC, or back-contact architecture, removes the front-side metal grid, reducing optical shading and allowing the front surface to capture more light.

But THBC is not a simple combination of TOPCon, HJT and BC. It is a structural redesign. TOPCon and HJT address passivation and carrier-selective contact; BC addresses electrode architecture and front-side optical utilization. THBC brings these elements together through high- and low-temperature hybrid passivation, selective carrier collection and conductive-layer design.

Dr. Xie Zhigang, Chief Scientist at Trinasolar’s Central Research Institute, explained the distinction during a media briefing: “TBC is essentially a TOPCon-based back-contact passivation technology; at its core, it still relies on homojunction diffusion passivation.” In his view, such a structure improves optical utilization, but does not fully resolve the limitations of hole collection, contact resistance and passivation performance.

THBC, by contrast, replaces part of the traditional high-temperature diffusion process with low-temperature heterojunction coating, while using selective collection structures and TCO conductive layers to improve interface passivation and electrical transport. It is therefore not merely a cell with electrodes moved to the back. It is a more complete reconstruction of passivation, carrier collection and contact design.

Core advantages: efficiency, power and manufacturability

The most visible advantage of THBC is higher front-side efficiency. By moving all metal contacts to the rear side, the technology creates a clean, grid-free front surface. This is especially valuable in applications where rear-side irradiance is limited or almost absent, such as residential rooftops, commercial and industrial roofs, and other space-constrained distributed generation projects.

Trinasolar has announced that its 210R large-area rectangular THBC cell, certified by Germany’s ISFH, reached a conversion efficiency of 28.00%. The significance lies not only in the number itself, but also in the industrial relevance of the format. This is a large, mainstream cell size designed with module production and future commercialization in mind, not a small laboratory sample detached from manufacturing reality.

The second advantage lies at module level. According to Trinasolar, THBC modules can deliver 15 W to 20 W more power than comparable traditional TBC products, while offering a temperature coefficient as low as -0.24%/°C and improved low-light performance. In high-value rooftop markets such as Europe and Australia, where available area, aesthetics and lifetime yield directly affect project economics, this can create a stronger value proposition for customers.

The third advantage is manufacturing compatibility. THBC is designed to grow out of the existing TOPCon production base rather than requiring an entirely separate manufacturing ecosystem. The key additional equipment mainly includes PECVD and laser tools. This matters in today’s industry environment. At a time of excess capacity and tighter capital discipline, a technology that can upgrade existing assets is more compelling than one that requires a wholesale rebuild.

THBC is also compatible with 110 μm to 130 μm thin wafers and can support future metallization cost-reduction pathways. Even so, Trinasolar’s approach is not built on aggressive cost cutting alone. In a product expected to operate for 20 to 30 years, material changes must be governed by long-term reliability, not short-term savings.

How THBC differs from TBC, ABC and HIBC

Back-contact technology has become one of the most active frontiers in solar innovation. ABC, HIBC and TBC all aim to push cell and module performance higher, but their technical starting points and manufacturing logic differ.

ABC emphasizes all-back-contact architecture and premium distributed applications. HIBC reflects a closer combination of heterojunction and back-contact structures. TBC can be understood as an extension of TOPCon into a back-contact format. THBC’s distinctive position is that it does not simply turn TOPCon into a back-contact cell, nor does it abandon the existing TOPCon manufacturing ecosystem. It uses TOPCon as the industrial base, integrates HJT-style passivation, and adds the optical and aesthetic advantages of BC.

Zhang Yingbin, Head of Trinasolar’s New Product Technology Center of Solar Product Division, described THBC as a technology that “fully considers the internal relationship and self-consistency among different technologies.” From the TOPCon perspective, he said, THBC can be understood as a further upgrade that absorbs the advantages of HJT and BC.

This positioning is important. THBC is not about choosing sides between TOPCon, HJT and BC. It is about recombining the strongest elements of each platform to serve a clearer industrial goal: higher efficiency, stronger manufacturability and better application-specific value.

Why Trinasolar chose THBC

Trinasolar’s move into THBC does not represent a reversal of its TOPCon strategy. It reflects a more precise understanding of market segmentation.

Large-scale utility projects, agrivoltaics and many bifacial scenarios continue to require modules with high bifaciality, strong low-light performance and excellent cost-performance ratios. TOPCon remains highly suited to these markets. By contrast, premium residential and commercial rooftops place greater value on front-side power density, limited-space optimization, visual appearance and long-term energy yield. These are precisely the scenarios for which THBC has been designed.

In other words, TOPCon addresses the economics of large-scale bifacial generation; THBC addresses the premium value of monofacial, space-constrained distributed generation. The two technologies are not in conflict. They are complementary.

Trinasolar’s industrialization pathway

Trinasolar has already moved THBC beyond the research phase. Its THBC pilot line has been established, production capacity is under construction, and initial capacity release is expected within the year. Future capacity planning will be adjusted according to market demand, with Europe, Australia and other high-value distributed markets expected to be among the first priority destinations.

The industrialization strategy is deliberately value-oriented. THBC is not intended to enter every market immediately as a commodity module. Its first task is to prove its value where power density, aesthetics and lifetime return matter most.

Dr. Xie noted through design optimization, the capital expenditure associated with PECVD can be substantially lower than that required by a pure HJT route. This gives THBC an industrial logic especially relevant today: innovation through upgrading, not replacement for replacement’s sake.

Why dual drive matters

For Trinasolar, the “TOPCon + THBC” dual-engine model has strategic importance.

First, it enables broader market coverage. TOPCon remains the workhorse for large-scale bifacial applications, while THBC provides a differentiated platform for premium monofacial distributed markets. Together, they allow Trinasolar to defend its scale advantage while expanding its presence in higher-value segments.

Second, it reduces technology-route risk. Solar technology evolves quickly, and no single route can serve every market at every stage. Developing TOPCon and THBC in parallel allows Trinasolar to respond more flexibly to changing customer demand, cost curves and regional preferences.

Third, it helps the company move from scale competition to value competition. In the next phase of the solar industry, leadership will not be defined only by shipment volume. It will also depend on technology judgment, product segmentation, manufacturing discipline and the ability to convert innovation into bankable customer value.

From price competition to technology value

The solar industry does not lack capacity. What it increasingly needs is technology that can create differentiated values while respecting manufacturing reality. THBC delivers Trinasolar’s answer: the next stage of crystalline silicon innovation should not discard the existing industrial base but build upon it.

THBC is therefore not the end point of crystalline silicon innovation. It is a new starting point. Built on TOPCon scale, strengthened by hybrid passivation and sharpened by back-contact architecture, it gives Trinasolar a next-generation platform for efficiency, manufacturability and customer value.

As a forward-looking technology innovation, the deeper significance of THBC is clear. It moves the conversation from cost per watt to value per square meter, from single-route competition to integrated innovation, and from capacity expansion to technology-led differentiation.