Today’s PV technology landscape reflects an ecosystem where multiple technologies coexist. While TOPCon has emerged as the standard, its contemporaries – heterojunction (HJT) and the more advanced back contact (BC) structure are also in high-volume production, with notable progress across all. Although some innovations remain technology-specific, others – especially at the module level – are increasingly applicable across platforms. This report offers a high-level overview of such developments.
Starting upstream, an important innovation in ingot production is LONGi’s proprietary TRCZ process, which offers precise resistivity control from seed to tail while maintaining RCZ’s cost advantages. TaiRay wafers made via TRCZ also enable better gettering. Regarding wafer specifications, BC is the most demanding, followed by TOPCon, while HJT is the most forgiving, particularly in terms of oxygen content.
In TOPCon, one major advancement is laser-assisted contact formation, which decouples metal contact recombination from contact resistivity. Deposition methods like LPCVD and PECVD now deliver comparable performance, having overcome earlier limitations. PVD is also emerging as a viable third option. Another notable trend is edge passivation, addressing defects from slicing large wafers into halves. Simultaneously, vendors are developing tools tailored to half-cell processing, a practice long established in HJT. Meanwhile, patent disputes have created uncertainty in some markets, prompting shifts away from TOPCon – especially in the US. Looking ahead, Several TOPCon manufacturers are exploring rear poly-fingers – borrowed from BC designs – to reduce parasitic absorption and boost efficiency by applying polysilicon only beneath rear metal contacts (see Progress Of TOPCon Technology In 2024).
For HJT, the foundational structure has already undergone a key shift from doped amorphous silicon to microcrystalline silicon, which has become a standard. The next frontier lies in metallization cost reduction. Manufacturers are moving in 3 key directions: increasing the number of busbars and eventually eliminating them through zero-busbar (ZBB) designs; lowering the paste laydown by reducing the finger width and reducing the silver consumption by lowering the silver loading; and ultimately going silver-free. Companies are also focusing on high mobility TCO material used in HJT processing (see Localized Front Contacts Boost HJT Solar Cell Efficiency To 23.4%).
BC technology is more opaque compared to its peers due to the proprietary nature of its development. However, insights from industry leaders like LONGi, AIKO, and SPIC reveal shared themes. BC is a platform that can be based on various cell architectures. However, the majority of manufacturers are using bipolar passivated contacts. Laser technology plays a vital role in BC solar cell manufacturing, particularly in enabling the rear-side structuring that defines this architecture. While there have been some growing pains with lasers in the beginning, today’s laser can very well support the throughput as well as quality requirements of BC cell makers. When it comes to metallization, all major BC manufacturers are actively exploring ways to reduce or replace silver, with a clear focus on copper-based solutions. And adopting ZBB is a common strategy to reduce silver consumption (see LONGi Records Highest Cell Efficiency For HIBC Technology).
At the module level, the industry is witnessing a shift from a ‘one-size-fits-all’ approach to products to application-specific designs. Module manufacturers are now tailoring their BOMs to meet the diverse demands of different climates, installation environments, and system configurations. As a result, almost every traditional component – be it glass, encapsulant type, backsheet, or frame – has an alternative, enhancing the application and integration spectrum of PV.
This text is part of the executive summary from the TaiyangNews Cell & Module Technology Trends 2025 report, which can be downloaded for free here.
