BC and tandem cells are pushing silicon efficiency limits through advanced design and materials innovation
Module reliability, degradation control and temperature performance are now as critical as efficiency
Solar modules are now high on aesthetics, lighter designs and come with application-specific features
Day 1 of the TaiyangNews Virtual Conference on PV System Technology Trends 2025 saw leading companies in the solar PV space report their technical innovations as presented at the world’s 2 leading solar trade shows, The smarter E/Intersolar Europe and SNEC, this year.
On Day 2 of the conference on June 26, 2025, TaiyangNews Head of Technology Shravan Chunduri recapped key highlights from Day 1, highlighting major innovations across the solar sector (see Innovation Drives Solar PV Forward Despite Market Headwinds).
Day 2 started with a presentation from AIKO, an industry leader in the back contact (BC) technology. AIKO has been advancing this cell technology that was originally conceptualized at Purdue University in 1975. It is now nearing the theoretical efficiency ceiling of 29.56% for monocrystalline silicon. The company says its all back contact (ABC) cells, already in mass production, deliver an average efficiency of 27.2%, while it claims 25.2% efficiency for its ABC Infinite modules.
These improvements are thanks to the various design innovations that Claudio Martins Godinho, AIKO’s Europe Service Director, listed at the conference as hidden bus ribbons delivering a 1.4% power gain, and ABC overlap interconnection, which increases active generation area by 0.4% while enhancing mechanical strength. The ABC modules are also high on sleek all-black aesthetics, superior partial shading performance, copper-based metallization for reduced costs, and a low temperature coefficient of -0.26%/°C, enabling better summer performance.
The manufacturer’s product lines span residential (Neostar series, up to 24.3% efficiency), C&I (Comet series, up to 655 W, 24.2% efficiency, with lightweight options at 8.6 kg), and utility (Polaris and Solaris series) applications.
With over 160 GW of global shipments and 6 factories totaling 35 GW of ABC production capacity, Godinho said that AIKO plans to scale up to 100 GW, while exploring perovskite tandem technologies to push conversion efficiency beyond 40% by 2040.
Trinasolar has reported record-setting certified efficiencies of 31.1% and 32.2% for perovskite-silicon tandem cells on large-area 210 mm wafers – among the highest globally, independently verified by Fraunhofer ISE. At the module level, it reached 30.6% efficiency on a 1,185.6 cm² area using innovations such as low-temperature encapsulation, room-temperature interconnection, and hybrid additives, shared Trinasolar’s Senior Engineer, Perovskite R&D at Trinasolar, Dr. Rui Xia.
Its standard-sized (2,384 × 1,303 mm) tandem modules, integrating 210 half-cut cells with dual-layer metallization, have steadily improved in output from 808 W in November 2024 to 841 W (internally tested) in May 2025. However, long-term stability remains a challenge as Xia shared that a 22-day outdoor test revealed a 21% power loss in tandem modules, compared to stable output from reference silicon modules.
Trina warns that without improved reliability standards, the potential LCOE gains from >30% efficiencies could diminish. According to Xia, the current IEC 61215 protocols do not capture perovskite-specific degradation mechanisms such as ion migration. While ISO standard-based methods are being discussed, no standard has been universally adopted so far. Trinasolar, which leads globally with 481 perovskite-related patent filings, has also signed a licensing agreement with Oxford PV for the Chinese market to accelerate tandem technology deployment.
Christian Comes, Huasun Energy’s Head of Business Development Europe, made a compelling, ‘provocative’ case for rethinking PV plant design, moving away from the traditional LCOE-driven metric as strategies revolving around the latter come under pressure. He cited curtailment and negative electricity prices during midday peaks in regions like California and Germany as signs of oversaturation.
Huasun championed vertical PV systems – particularly its Kunlun HJT modules with 95%+ bifaciality – as a smarter alternative backed by detailed modeling and field tests. Strong hail resistance and compatibility with agrivoltaics can ensure vertically placed modules deliver up to 21% higher revenue without storage and rival the performance of PV+BESS setups at lower CapEx and complexity.
Vertical systems shift generation to mornings and evenings, aligning better with power prices and grid needs, explained Comes. As PV plant revenue becomes increasingly time-of-day dependent, Huasun sees vertical HJT as a resilient solution for the next era of solar deployment.
GoodWe is transitioning from an inverter specialist into a comprehensive smart energy solutions provider, underscored by its AI-enhanced Home Energy Management System (HEMS) for residential and C&I applications. The system smartly integrates PV, storage, EV charging, and heat pumps to optimize consumption, enable peak shaving, and support dynamic energy trading.
Jonas Ding, GoodWe Europe GmbH’s Technical Product Director, highlighted the company’s all-in-one residential solution that allows flexible capacity expansion from 5 kWh to 48 kWh, all with simplified installation and one-click commissioning. Engineered for versatility and resilience, the systems offer reliable performance down to -20°C, multi-layer safety features, and compact designs optimized for off-grid, backup, and hybrid use cases. He stressed that GoodWe’s C&I storage solutions offer up to 20% CapEx savings thanks to features such as smart load control, generator integration, power exchange capabilities, and grid service trading optimization.
The company also unveiled its upcoming ET 100 hybrid inverter – marketed as the quietest in its class – featuring 21 A per string, 200% PV oversizing, and intelligent thermal management, with a Q3 2025 launch planned.
DAS Solar’s Director of Global Technical Support, Leo Chang, presented a comprehensive roadmap for high-efficiency n-type PV, focusing on the evolution of its TOPCon and BC technology. He detailed a multi-stage development of TOPCon, from early designs with standard rear contacts and 23.5% efficiency, to TOPCon 2.0 with 16 busbars and fine fingers achieving 24.5%, and onward to innovations like thinner polysilicon, laser-based selective emitters, and laser-induced firing that pushed TOPCon 4.0 to 26.3% efficiency.
Its latest TOPCon 5.0 variant introduces dual-sided poly fingers, cross-sectional passivation, and edge passivation, with a target of 27% cell efficiency. Addressing industry challenges such as ultraviolet-induced degradation (UVID), DAS Solar implemented enhanced passivation and UV-converting encapsulants, securing TÜV Rheinland UVID certification. To bring cell gains to the module level, it launched the DAON 5.0 platform, aiming for 24% module efficiency and 650 W+ output, with flagship products like the DH132TE expected to exceed 655 W by 2027.
At the conference, Chang also unveiled its 3rd generation n-type BC technology module, calling it double-side Conductive Back Contact (DBC) cell technology. Under DBC 3.0, it targets module outputs of 655 W by Q3 2025 and up to 670 W by Q1 2027 (66-cell), with 48-cell variants reaching 490 W. The DBC 3.0 cells deliver over 24% efficiency, featuring a sleek, grid-free, light-trapping all-black design.
DBC 3.0 cells use SiOₓ/poly-Si contacts on both p- and n-type regions, exceeding 27.2% efficiency. These modules are available in utility (66-cell DH132TE) and rooftop (48-cell DH96TE.A-Black) formats. Mechanical upgrades include 1.6 mm double glass (-4.7 kg), hydrophilic self-cleaning frames, and offshore-ready designs with PID-resistant materials.
HyperStrong, active in the BESS segment since 2011, has deployed over 30 GWh across more than 300 projects worldwide. The company emphasized its safety record – 35 million cells analyzed with zero incidents. Its portfolio spans residential, C&I, utility, and EV charging, with a focus at the event on the HyperCube (C&I) and HyperBlock (utility), particularly the HyperBlock M series, which ranges from 300 kWh to 12.8 MWh in DC and AC-integrated versions.
Described by HyperStrong International’s EMEA Solution Manager, Mingxuan Li, as the most compact in its category, the HyperBlock M delivers 3.2 MWh to 25.6 MWh. Its 12.8 MWh variant offers land investment savings of about 36.8% (DC) and 26.3% AC, compared to equivalent 5 MWh systems. Designed for 4-8 hour applications, a standard 50 MW / 200 MWh installation requires just 1,687 m² – cutting land use and upfront investment, making it ideal for space-constrained utility-scale projects, explained Li.
HyperBlock M features 18-layer protection, AI-based thermal runaway alerts up to 7 days in advance, and up to 50% lower thermal losses. It delivers 94% round-trip efficiency for 2-hour systems, and 93% for 4-hour systems, with 98% availability in 6 months, and over a 25-year design life.
Compared to 6.4 MWh analog systems, HyperBlock M offers 28% higher energy density, 20% lower cabling costs, and reduced land footprint, he added.
Panel Discussion
Participating in a panel discussion with TaiyangNews Head of Technology Shravan Chunduri, the panelists reflected on and shared insights into the latest innovations and trends at The smarter E/Intersolar Europe 2025 and SNEC.
The speakers were unanimous in their view that while TOPCon is expected to dominate the industry as its workhorse at least till 2027, BC technology is coming up strong, as was clear at the 2 recent shows. However, with BC, the high cost acts as a deterrent, as many producers are still grappling with profitability. For BC to beat TOPCon, its costs need to come down.
CRU/Exawatt’s Head of PV, Alex Barrows, explained that in 2028-29, when manufacturers can think of upgrading or changing production lines, then BC can grow faster.
AIKO’s Europe Service Director, Claudio Martins Godinho, added that by then, tandem technologies would have advanced significantly, and BC works better in a tandem structure compared to other technologies. This will also expand its market share. For now, the focus of the industry and the need of the hour is cell standardization, 182 mm x 210 mm, which will also contribute to lowering transportation costs.
GCL System Integration’s Technical Director for EU & LATAM, Vitor Rodrigues, pointed to the growing requirement for low-carbon products in the industry, which it caters to with the FBR production method. Between low-cost and low-carbon, Rodrigues sees customers opting for low-carbon as the more attractive proposition.
TaiyangNews ran a live blog during the event on both days of the PV System Technology Trends virtual conference, which can be accessed here.