Solar panel manufacturers in India are exploring new technologies beyond TOPCon solar cells. Back-contact (BC) solar cells appear attractive due to their potential advantages, but many believe this technology has not yet matured sufficiently.
Most solar panel manufacturers in India have shifted their module production from PERC (Passivated Emitter and Rear Contact) technology to TOPCon (Tunnel Oxide Passivated Contact). Currently, TOPCon has become the primary option for mass production of solar cells due to its ease of transition and lower costs. This technology is rapidly replacing PERC due to its enhanced energy conversion capabilities and reduced production costs. It is also gaining popularity due to its similar efficiency to more advanced technologies like HJT (Heterojunction).
While TOPCon technology is dominating the Indian solar industry, some experts predict that back-contact technology (IBC – Interdigitated Back Contact) and other similar technologies (which offer higher conversion efficiencies) will capture part of the TOPCon market by 2030. The BC technology, with its unique design that places all connections at the back of the cell, eliminates shading losses from front busbars (electrical connections), which can result in higher efficiency.
Currently, only a limited number of global manufacturers are taking commercial steps to develop BC technology, although major companies like Aiko, Longi, and Maxeon could rapidly scale this new technology for mass production. These manufacturers, with their experience and resources, can help accelerate the adoption of BC technology.
BC cells represent a range of cell architectures that can sometimes be combined with other technologies like TOPCon or HJT. In BC modules, all connections and structures necessary for current transfer are located on the back side, eliminating front busbars, which reduces shading losses and increases efficiency. Producing BC technology requires investment in new equipment and more complex, specialized, and sensitive processes that are not essential for TOPCon production.
Indian manufacturers, operating with low profit margins, plan to continue producing TOPCon in the short term, focusing on further developing this technology rather than investing in BC solar, which still faces challenges in mass production. Reliance Industries is currently the only manufacturer in India with established plans for BC production. The company aims to commercialize HJT-IBC technology by 2026. Notably, the company is also developing first-generation bifacial panels with 26% efficiency using HJT technology.
TOPCon at the Forefront
Since 2021, TOPCon has emerged as a popular successor to PERC among manufacturers, including in India. TOPCon offers a simpler and cheaper transition and currently has a performance level similar to HJT, its main competitor. This technology has garnered significant interest from manufacturers due to its ease of production and lower initial investment. While BC is considered the next evolutionary step in solar technology (due to its potential for higher performance compared to other silicon cell technologies), the transition to mass production of any BC technology is significantly more complex than upgrading to TOPCon.
The CEO of Chinese solar cell manufacturing equipment company Yingkou Jinchen Machinery noted that transitioning to BC technology requires substantial investment to change production lines, procure new equipment, and retrain personnel. For Indian manufacturers, especially those working with low profit margins, this can pose a challenge. The high initial costs may deter some manufacturers, particularly smaller ones or those that have recently upgraded.
BC structures can be applied to various types of cells, including TOPCon and HJT, to enhance cell efficiency. BC solar cells have the potential to achieve efficiencies of up to 29.1%, recognized as the highest performance potential among all known silicon solar technologies. However, manufacturing bifacial cells presents a greater challenge. Increased production on the front side of IBC may not justify the higher costs compared to TOPCon.
Balachandar Krishnan, COO of the solar cell manufacturing plant at Indosol Solar, stated that BC solar cells may not capture at least 10% of the market share by 2028. He pointed out several key barriers to IBC adoption, including high capital costs, non-standardized processes with varying pathways, and increasing operational costs. Reliability issues, lower yields, and increased electrical rejection and failures due to manufacturing complexities also present challenges.
Additionally, the bifacial factor of BC solar cells is 70%, while TOPCon cells have an 80% factor. These figures indicate that BC cells can absorb 70% of the light received from their rear side, while TOPCon cells increase this ability to 80%. In other words, bifacial TOPCon cells absorb light more effectively from both the front and back, generating more energy, which may impact the difficulty of adopting BC technology.
Gyanesh Chaudhary, chairman and CEO of Vikram Solar, stated that cost sensitivity in the Indian market means the overall cost of solar energy, per watt-peak of panel production capacity, is critical. Currently, BC technology involves complex processes and high investment. This technology is still in the development stage, with more advancements expected by 2025.
Preparing for Transition
Until BC technology becomes established as a more viable option, manufacturers prefer to focus on existing processes in their production lines to enhance cell efficiency. However, many solar panel manufacturers have included BC technology in their technology roadmaps, as several leading module manufacturers in India have indicated to pv magazine.
Krishnan from Indosol said, “For tier-1 solar cell suppliers, TOPCon has achieved 26% efficiency by introducing the LECO [laser-enhanced contact opening] process and using edge passivation as a standard process in their production lines.” In this context, Krishnan believes that TOPCon still has greater potential to exceed 28% efficiency in cells by adopting a range of innovations.
He added, “With this clear-cut roadmap in mind, manufacturers will focus on leveraging the maximum potential from existing TOPCon lines rather than on a newer technology that has yet to be proven in mass manufacturing in terms of cost, yield, and reliability.”
While some manufacturers may adopt BC technology earlier, understanding and leveraging the aforementioned possibilities for TOPCon should keep this technology competitive in the medium term. Juhi Marwadi, director of module maker Pixon, stated, “With back-contact routes promising even higher efficiencies than TOPCon, Indian manufacturers must focus on integrating advanced techniques like selective doping, light trapping, and surface passivation. This will help them remain competitive in the global market as other manufacturers also shift to high-efficiency cells.”
Regarding the transition to BC, government incentives, technology partnerships, and workforce training are essential to facilitate the process.
Marwadi stated, “Manufacturers need to assess their existing production lines and understand the degree of compatibility for future BC manufacturing.” She explained that this assessment includes optimizing processes such as contact printing, passivation, and module assembly, among other aspects. To ease the transition to BC, Marwadi anticipates that Indian manufacturers will seek partnerships with international tech companies and research institutions specializing in BC solar technology. Such collaborations could accelerate the technology transfer process and reduce the learning curve for new approaches. She also noted, “Manufacturers will need to invest in upskilling their workforce to manage the more advanced IBC processes.” Marwadi concluded by mentioning that the Indian government’s PLI [production-linked incentive] scheme and other solar industry incentives might provide the necessary financial support for manufacturers transitioning to next-gen technologies like IBC.
Hardip Singh, COO of Grew Energy, stated that the rapid pace of technological advancements in the solar industry poses a significant challenge for Indian manufacturers. The rate of return on investment in manufacturing technology often lags behind these advancements. Singh predicts that this trend will continue, requiring manufacturers to either adapt to new conditions or find innovative solutions. He also noted that manufacturers have already sought government support to address this issue.
Suhas Donthi, president and CEO of Emmvee Group, stated, “With the anticipated transition to BC panels as early as 2025, we are closely monitoring the advancements in BC technologies. We are prepared to introduce these cutting-edge solutions to the Indian market when they reach the right stage for large-scale commercial deployment.”
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