3SUN is scaling HJT production to 3 GW through its integrated gigafactory in Catania, representing one of Europe’s early large-scale manufacturing efforts
HJT enables a simplified, low-temperature process flow, operating below 200°C with around 6 steps versus ~14 for TOPCon, supporting higher automation and process control
Perovskite-silicon tandem development is progressing toward industrialization, with pilot-line scaling and efficiencies above 30% demonstrated
Heterojunction (HJT) technology is already established as a high-performance solar cell architecture, offering strong efficiency and bifaciality. Manufacturers are now focused on expanding GW-level production and improving cost competitiveness, particularly in Europe, where local capacity remains limited despite strong demand.
At the TaiyangNews High-Efficiency Solar Technologies 2025 Conference, Marina Foti, Head of Advanced Technology Development, R&D and Technology Transfer at 3SUN, presented the company’s experience in scaling HJT solar cell and module production in Europe.
At the heart of this effort is 3SUN’s gigafactory in Catania, Italy. The facility, known as La Fabbrica del Sole, is designed to produce 3 GW of cells and modules. It is located in the Etna Valley, a well-established semiconductor hub.
The project represents a significant industrial investment in Europe. Of the total funding of about €1 billion, around €200 million comes through European and Italian public initiatives. 3SUN has already started production at the gigafactory, indicating Europe’s entry into large-scale manufacturing of advanced n-type technologies.
The facility spans roughly 200,000 m² and integrates both cell and module production. It currently supports a daily capacity of around 800,000 cells and 14,000 modules.
3SUN has developed a module portfolio covering residential, commercial, and utility-scale applications, including B48 and B60 modules, with larger-format B66 modules expected to enter the market soon (see 3SUN’s Fully Made-In-Europe HJT Module).
Despite all this progress, its ramp-up remains influenced by market conditions. Foti noted that while the company has commissioned all the equipment, it has yet to start full-capacity operations due to current industry dynamics.
Foti’s presentation also focused on the HJT’s technical advantages, which, she noted, are several compared to conventional architectures. HJT provides strong surface passivation, high bifaciality, and a low temperature coefficient, supporting higher energy yield at the module level. It operates below 200°C, while TOPCon processes can exceed 800°C. The lower temperature simplifies processing. HJT typically involves around 6 steps, compared to roughly 14 for TOPCon, making process control easier and enabling higher automation, adds Foti.
The symmetric structure of HJT cells also enables thinner wafers, reducing silicon consumption. Material improvements, including nanocrystalline silicon layers, help improve carrier transport, while enhanced TCO design supports higher conductivity and transparency.
While HJT’s performance is not in question, its cost remains a key challenge. The technology traditionally relies on higher silver consumption and indium-based TCO layers.
3SUN outlined several pathways to address this. One approach is the transition toward silver-copper pastes, with ongoing efforts to further reduce silver content. Another is the adoption of copper metallization, supported by the TCO barrier layer that limits copper diffusion into silicon. The company is also working toward indium-free TCO solutions. In addition, interconnection technologies such as zero-busbar designs are being explored. These approaches reduce silver usage and improve module performance by minimizing shading losses.
3SUN is also developing perovskite-silicon tandem cells that integrate a perovskite top cell with an HJT bottom cell in a 2-terminal architecture. The technology is moving from lab-scale cells to pilot-line production on full wafer formats, with the company targeting initial industrial deployment before the end of the decade. This work is being carried out in collaboration with CEA-INES.
Access the full presentation here.