TOPCon remains the dominant mainstream technology, supported by steady efficiency gains, cost advantages, and widespread adoption in China and beyond
Wafer, cell, and metallization innovations are improving performance while reducing material use and production costs
TOPCon will likely transition directly to tandem architectures, with perovskite-silicon tandems seen as the most promising route to push efficiencies above 30%
The Tunnel Oxide Passivated Contact (TOPCon) solar cell technology has established itself as a worthy successor to PERC, which ruled the roost for several years. Having become the industry workhorse in a short span of time, this technology is now branching out from China to other emerging manufacturing centers around the world. It is also being trailed by other high efficiency technologies – back contact (BC) and heterojunction (HJT) – even as tandem is on the horizon, though there’s still a long way to go.
In a world where technological innovations are taking place by the minute, how much more TOPCon can improve to stay ahead of the competition is something that the company boardrooms are now discussing. To know what’s happening in the TOPCon space and what the future holds, TaiyangNews brought together industry stakeholders on Day 2 of its High Efficiency Solar Technologies 2025 Conference on December 4.
TOPCon Drives Solar Technology Progress
TOPCon’s foundation – passivated contact technology – dates back to the 1980s and was first industrialized in SunPower’s Gen III IBC cells, shared keynote speaker Fraunhofer ISE Head of Technology Transfer Jochen Rentsch. Fraunhofer ISE named the technology TOPCon in 2013, and companies like Jolywood and First Solar began early industrial production soon after.
A key milestone came in 2019 with the LECO development, which enabled the modern TOPCon process. Mass adoption followed between 2020 and 2022, supported by innovations such as Passivated Edge Technology to reduce losses.
Today, TOPCon has become the leading solar cell technology, with current mass-production efficiencies of 25% to 26% and a record of 27.79%, according to Rentsch. HJT, he said, is losing market share, while IBC is progressing more slowly and still remains a premium product for specific markets and applications.
Silver use has risen due to TOPCon’s metallization needs, putting pressure on production costs. It is also driving innovation, as the industry is now moving toward copper-based alternatives, he pointed out.
Rentsch also delved into the current hot topic in the industry – TOPCon patents. For TOPCon cell design and module implementation, there are different implementation routes, which makes a thorough analysis of the patent situation quite complex. However, the same is true for most other industrially relevant cell architectures, such as silicon HJT, BC, and even perovskite-silicon tandem.
As silicon approaches its practical efficiency limits, Rentsch expects future progress from perovskite-silicon tandem cells aiming for 30% and above, with hybrid production routes seen as the most promising.
NexWafe’s Direct Wafer Approach
Frank Siebke, Co-Founder and SVP Business Development at NexWafe, elaborated on the company’s patented direct gas-to-wafer process. What differentiates it is that it eliminates 6 steps from conventional silicon wafer production. Using its patented wafer cloning technology, the company’s production process goes directly from Chlorosilane to wafer, thereby cutting energy and resource use.
He added that NexWafe’s epitaxial wafers produced through this method contain 20–40 times less oxygen than Cz wafers. These can also be tailored for technologies such as HJT and tandem cells.
NexWafe is currently completing its in-line cold-wall reactor to increase throughput and quality, and targets an early-2027 date for mass production. It is also positioning the 50 MW Bitterfeld, Germany, line to produce thin p-type wafers for high-value space applications. Siebke added that at a GW-scale, the process should enable costs below conventional silicon wafers due to significantly lower energy demand.
Trinasolar’s TOPCon 2.0 Progress
Ling Zhuang, Product Manager at Trinasolar, discussed the company’s TOPCon 2.0, which is designed to raise energy yield by combining i-TOPCon Ultra technology, higher bifaciality, and improved low-irradiance performance.
Between 2025 and 2029, the company aims to enhance its n-type cell design with better passivation, reduced optical losses, and finer metallization to achieve over 27% cell efficiency and over 25% module efficiency. For 2030, the roadmap moves toward perovskite tandem integration with i-TOPCon tandem, aiming to surpass 30% cell efficiency and 28% module efficiency. It will incorporate high-quality perovskite thin-film deposition technology, low photovoltaic-loss composite junction technology, and high-efficiency passivation technology.
Zhuang added that TOPCon and BC modules show similar shading losses in ground-mounted projects. However, due to structural differences, TOPCon can deliver 1.7% more backside power and around 7% higher output than xBC under low-light conditions.
DET for Better N-Type Performance
Roy Ren, Solar Cell Technology Director at DMEGC Solar, outlined the various technology solutions that the manufacturer incorporates to produce high-performance n-type solar modules.
In the list for optimization opportunities he shared were the use of poly-finger, light-trapping, passivation layer optimization, meshless printing, hydrogen passivation, interface cleaning, module encapsulation optimization, high-transparency module materials, among others.
Ren specifically highlighted the Defect Elimination Technology (DET). Although it follows the edge passivation approach, Ren emphasized that the repair of the defects at the cut edges is much more intensive with DET.
TOPCon All The Way
Homer Chen, the Associate Dean of Research Institute, Shenzhen S.C New Energy, highlighted the company’s smart production line that’s designed to enable higher TOPCon cell throughput.
The company claims to be supplying over 70% of global TOPCon equipment installations, while also catering to HJT and perovskite tandem. Its equipment uses a PECVD process, since LPCVD is more expensive and also faces the challenge of poor uniformity and long process times. Additionally, the unit manufacturing cost of LPCVD is about 15% to 18% higher than PECVD, mainly due to quartz consumption, high energy consumption, and capacity limitations.
Chen claims that TOPCon solar cells produced with Shenzhen S.C equipment achieve over 25.5% efficiency and more than 98% yield in mass production. There is further scope for improvement in TOPCon optimization with oxidization layer thickness control, doping and firing of poly-Si, reduction of contact resistance, minimizing optical loss, and bifacial design.
He said that in the future, the company plans to employ artificial intelligence to enable autonomous process adjustments through feedback control. It is also continuously increasing the wafer loading capacity.
Chen shared that as of Q4 2024, a majority of Chinese manufacturers were into TOPCon production. Out of China’s 573 GW production capacity, 562 GW was TOPCon.
This technology also provides the lowest cost of ownership (CoO) at 2.0 cent/W (non-wafer cost in Mainland China), compared to 2.8 cent/W for HJT and 2.6 cent/W for xBC, and also gives the fastest return on investment within 2 to 3 years. For HJT, it is around 5 years.
As the world moves towards TBC, according to Chen, PE-poly in-situ doping and selective deposition will be ideal for complex rear patterning. It also enables modular, inline production and comes with a lower thermal budget. Nevertheless, Chen believes that TOPCon will be the leading industry trend for the next 10 years.
Metallization Solutions for TOPCon 3.0
DKEM’s Director of New Technology Development, Fangqing Guo, explained that the company has introduced new high-efficiency, cost-effective metallization pastes designed for the transition to TOPCon 3.0 solar cells.
While TOPCon 2.0 had a wider contact window at both front and rear sides that enables a low laydown approach, Guo said that TOPCon 3.0 uses edge passivation (EPD), ultra-fine printing technology, and laser-enhanced firing effect for poly-finger at the rear side.
Using a laser-enhanced firing process, DKEM improved contact resistivity and lowered recombination on both the front and rear sides, making the materials compatible with advanced cell architectures and ready for mass production.
Guo also pointed out that DKEM offers silver-lean and silver-free options to meet different efficiency and cost requirements, helping support more sustainable and flexible PV manufacturing.
Panel Discussion
In conversation with TaiyangNews Head of Technology Shravan Chunduri, the panelists were unanimous in their opinion that TOPCon will remain a robust mainstream technology with room for meaningful efficiency gains and a clear upgrade path toward tandem cells.
Fraunhofer ISE’s Jochen Rentsch highlighted that the biggest advantage over the past year has been steady production improvements, but warned that IP issues remain difficult since production processes – not equipment – pose the real risk. He stressed that efficiency upgrades must make commercial sense, as complex steps with minimal gain are not always justified, and recommended that the industry continue optimizing existing TOPCon, especially on the rear side. He also argued that manufacturers can move directly from TOPCon to tandem cells without first adopting BC architectures.
Shenzhen S.C New Energy’s Homer Chen said that while TOPCon will eventually hit its efficiency ceiling, the technology remains strong and practical, with ‘realistic industrial efficiency’ being the most important recent innovation. He emphasized equipment-level advances such as improved edge passivation, backside polysilicon, annealing strategies that reduce parasitic absorption, and more advanced silver pastes. On scaling TOPCon Plus, he noted that it resembles standard turnkey lines but requires highly precise deposition and doping to improve tunneling layers and reduce recombination.
DKEM’s Fangqing Guo attributed much of TOPCon’s recent progress to fine-line metallization, explaining that pushing screen openings below 6 microns reaches the limits of existing silver and glass powder, forcing major changes in powder formulation and processing. He said the IP landscape remains complex but manageable. On the technology pathway, he argued that bipolar structures offer limited efficiency gains for TOPCon, so most customers avoid heavy investment and instead pursue simpler front-side optimizations that mimic some of bipolar’s benefits. Looking ahead, he said cost reduction – especially lowering silver use – will be the decisive factor, and like the others, he believes the industry can move directly from TOPCon to tandem without needing to pass through BC.
The TaiyangNews High-Efficiency Solar Technologies 2025 conference is in its last leg, with the 4th and final day scheduled today. Register free here as industry stakeholders and experts come together for HJT and its future.
