Amid overcapacity in the PV sector, particularly for TOPCon, BC technology is seeing new production investments in China, led by Maxeon, AIKO, LONGi, and SPIC
Back contact cells eliminate front-side metallization, reducing shading and improving efficiency, but require precise engineering of passivation, laser patterning, and metallization
LONGi and AIKO have committed to large-scale BC capacity, with targets up to 50 GW and 25 GW respectively, while SPIC continues to scale its TBC production alongside TOPCon lines
The most significant trend in cell architectures today is the rise of back contact (BC), particularly in China. Amid a severe overcapacity situation in PV manufacturing, especially for TOPCon technology, virtually all major manufacturers have paused new expansion plans within China. In this environment, the only notable capacity building that is happening revolves around BC technology, albeit still in relatively modest volumes. Nearly every leading PV manufacturer is now establishing at least a pilot line and working on BC development behind the scenes. However, 4 companies are actively driving the technology on the commercial front: the pioneer of back contact technology, Maxeon, along with AIKO, LONGi, and SPIC.
Given the competitive landscape, much of the innovation and development around BC remains confidential. Nonetheless, TaiyangNews had the opportunity to engage directly with 3 of these leading players - AIKO, LONGi, and SPIC - to gain insights into the evolution of BC. While not all questions were answered fully, as expected due to confidentiality constraints, the executives provided valuable perspectives on the current status and the direction of BC development. Until a dedicated, in-depth report covering all aspects of BC technology is published, this article summarizes the key takeaways from our discussions with these industry leaders and serves as a preface to our upcoming exclusive report (see Betting On Bifaciality, LONGi Promotes Its BC Products For Utility).
Back contact solar cell technology refers to a design where all the electrical contacts – both positive and negative – are moved to the rear side of the solar cell, leaving the front surface entirely free of metal. This architecture eliminates shading losses caused by front-side metallization (which is present in conventional solar cells), allowing more sunlight to be absorbed and improving the overall efficiency of the cell. In BC cells, light enters through a clean, uninterrupted front surface, while the rear side is carefully structured with interdigitated (alternating) positive and negative contacts to collect the electrical current. This structure requires precise engineering, including advanced passivation layers, laser patterning for contact separation, and specialized metallization techniques (see AIKO Doubles Down On Innovation With Efficient & Smarter Modules).
LONGi’s journey toward BC began around 2016-2017, during a period when the company was simultaneously investing heavily in multiple cell technologies, including PERT, TOPCon, and HJT. LONGi’s guiding philosophy has always been to maintain broad R&D exploration while narrowing production choices based on rigorous scientific evaluation. The motivation for prioritizing BC crystallized during a period when all new world records for silicon-based single-junction solar cell efficiency were achieved with BC structures. For example, SunPower’s BC cell with passivated contacts achieved 25.2% efficiency on a fully manufacturable platform, while Kaneka’s heterojunction-based BC cell reached a groundbreaking 26.3%. These milestones were significantly higher than the commercially manufacturable efficiencies of PERC cells at the time. LONGi recognized that while cost reduction is vital for PV market success, true long-term value lies first in achieving higher efficiencies, and BC offered a clear and scalable path for both efficiency gains and future cost optimization. Following an exhaustive first-principles analysis, LONGi concluded that BC technology had vast untapped potential and that its primary barriers, mostly related to cost, were technically surmountable through targeted innovation.
Similarly, AIKO’s decision to focus on BC was the result of a deliberate evaluation process across multiple high-efficiency technologies. Its R&D efforts included work on HJT, TOPCon, and BC cells. However, after careful consideration, AIKO selected BC for mass production, citing its combination of highest efficiency potential, superior aesthetics with a pure black appearance, and greater energy yield. According to the company, BC modules not only exhibit a lower temperature coefficient and better degradation rates compared to other architectures, but they also demonstrate higher temperature tolerance and better partial shading resilience – important traits that enhance real-world energy generation.
Convinced by these advantages, all 3 companies have built commercial capacities. Leading the trio, LONGi plans to reach a total BC production capacity of 50 GW, with its HPBC 2.0 technology. AIKO, another major proponent of BC technology, is also expanding at a rapid pace. The company currently operates 2 facilities, one with 10 GW BC cell and module production capacity and another with 15 GW. AIKO is also adding a new facility with 25 GW capacity, with the module part of it already operational. SPIC commissioned its initial 200 MW IBC line in 2019, which has since been upgraded to TBC (TOPCon Back Contact) with a current capacity of around 240 MW. Looking ahead, SPIC has plans to expand further, with new BC production lines under consideration that could range from 1 GW to 5 GW, depending on funding availability. Additionally, SPIC maintains about 400 MW of TOPCon production capacity alongside its BC operations.
This text is an excerpt from the TaiyangNews Cell & Module Technology Trends 2025 report, which can be downloaded for free here.