TOPCon Solar Panels: The Next Frontier in Solar Revolution

TOPCon solar panels are quickly gaining traction in the Indian market, with their adoption rate surpassing even that of Mono PERC technology. This rapid acceptance stems from TOPCon's innovative design, which blends the most advantageous features of traditional solar cell technologies into a single, advanced architecture while effectively addressing their limitations.

The advantages of TOPCon over other solar technologies position it as a leading choice for India’s expanding solar market. According to Clean Energy Associate’s (CEA) market intelligence, TOPCon is projected to capture nearly 50 percent of the market by the end of this year.

Let’s dive deeper into the particulars of this technology, its current status, and the future prospects in India.

What is TOPCon Solar Panel Technology?

TOPCon, or Tunnel Oxide Passivated Contact, is an advanced solar cell technology that enhances efficiency and energy output beyond what traditional solar cells can achieve. It features a thin, passivating tunnel oxide layer that improves carrier selectivity and minimises contact resistance, allowing for a more efficient conversion of sunlight into electricity.

In essence, TOPCon merges the best aspects of earlier technologies, such as PERC (Passivated Emitter and Rear Cell) and heterojunction cells. This combination enables TOPCon cells to reach superior efficiency levels of over 28 percent, significantly higher than the approximately 20 percent efficiency typical of PERC cells.

Working Mechanism: A Competitive Edge

TOPCon solar technology excels in the market due to its sophisticated working mechanism, which significantly boosts efficiency and performance. 

The process begins with the front side of the cell, which features a standard phosphorus-diffused emitter similar to traditional solar cells. This emitter is responsible for absorbing sunlight and generating electric current. Above the emitter lies a thin, insulating tunnel oxide layer made of silicon dioxide. This layer plays a dual role, efficiently transporting electrons generated by the emitter while reflecting harmful UV rays that could damage the cell. 

Next, a Transparent Conductive Oxide (TCO) layer, typically made of indium tin oxide, is applied. This TCO layer is crucial for conducting and transporting the generated electrons while allowing sunlight to pass through it. The rear side of the cell is passivated to reflect any unabsorbed sunlight back onto the front side, minimising electrical losses. 

Finally, a highly doped back surface field is added below the rear passivation layer, establishing the negative polarity and directing electron flow in one direction across the external load. This intricate design allows TOPCon technology to achieve superior performance by maximising electron efficiency and reducing energy losses.

Advantages of TOPCon Solar Technology

TOPCon solar modules offer several compelling advantages that position them as a disruptive force in India's solar sector. 

Beyond their higher efficiency, these modules deliver outstanding performance under real-world operating conditions, such as Normal Module Operating Temperature (NMOT). This capability maximises energy yield and return on investment (ROI) over a lifespan of more than 25 years.

The tunnel oxide layer in TOPCon cells helps regulate temperature, making them less susceptible to efficiency losses under high temperatures, intense irradiance, and other environmental stresses. This is especially critical in India's tropical climate, where high temperatures are common.

Additionally, the advanced rear-side passivation in TOPCon cells virtually eliminates light-induced degradation (LID), ensuring reliable energy delivery across diverse Indian environments. Combined with high-quality manufacturing, TOPCon modules exhibit extremely low annual performance degradation of less than 0.25 percent, further enhancing their lifetime value.

In contrast to Hetero Junction Technology (HJT), which involves more complex and expensive manufacturing processes, TOPCon technology requires less new capital investment for manufacturers who already produce mono-PERC modules. As TOPCon technology moves from pilot projects to mass production, industry experts anticipate a significant reduction in costs—potentially dropping to as low as 5 cents per watt, making it more affordable than current PERC technology.

With its superior efficiency, higher energy yield over its lifetime, and rapidly decreasing production costs, TOPCon solar technology is on track to deliver the lowest Levelized Cost of Electricity (LCOE) among all photovoltaic options. TOPCon and PERC warranties also state similar annual degradation rates of around 0.4 percent. However, TOPCon has a lower first-year degradation of 1 percent versus PERC’s 2 percent. This will make solar energy more accessible and economically viable for Indian homes and businesses, further driving the nation's transition to renewable energy.

TOPCon Lighting India: A Bright Future Ahead

The latest Approved List of Models and Manufacturers (ALMM) for solar module makers in India includes several companies that have introduced new TOPCon technology production lines. According to the ALMM, 10 PV module manufacturers, representing about 11 percent of the total, are currently producing TOPCon modules in India. 

With 93 PV module manufacturers now registered on the ALMM list, the market share of TOPCon technology is expected to grow significantly, potentially reaching up to half in the coming months.

Top TOPCon Manufacturers in India

Leading Indian solar module manufacturers, including Waaree Renewable, Gautam Solar, Mundra (Adani) Solar, Premier Energies, RenewSys, Luminous, Rayzon, Emmvee, Pahal Solar, and Ganesh Bharat, are making significant strides in producing advanced TOPCon technology-based solar modules.

RenewSys, with a PV module capacity of 1.85 GW, including 600 MW dedicated to TOPCon, plans to expand further with an additional 1 GW unit by April 2025 and another 2 GW by April 2026. Premier Energies, meanwhile, has filed for an IPO to raise over INR 1,500 crore, intending to invest INR 1,168 crore in establishing a 4 GW TOPCon solar cell and module manufacturing facility in Hyderabad.

Emmvee, based in Bangalore, is also gearing up to commission a 1.5 GW TOPCon wafer-to-cell manufacturing plant, adding to its 3 GW production capacity. The company recently earned recognition as the only Indian manufacturer and one of just four globally to achieve top performer status in all Kiwa PVEL PQP Testing Categories.

Gautam Solar's manufacturing line includes a 500 MW high-efficiency automatic production line for TOPCon modules, while Luminous Power Technologies has launched a fully automated solar panel factory in Rudrapur, Uttarakhand. This 250 MW plant, expandable up to 1 GW, is equipped to produce TOPCon panels in monofacial and bifacial variants, alongside polycrystalline, monocrystalline, and n-Type panels.

These developments underscore the growing momentum behind TOPCon technology in India, as manufacturers increasingly invest in this high-efficiency solar solution to meet the rising demand across residential and utility-scale projects.

Challenges 

Currently, only a few companies in India are producing TOPCon cells, leading to an industry capacity that falls short of meeting the domestic demand for PV modules. This shortage of locally produced cells presents a challenge not only for TOPCon but also for manufacturers of mono Passivated Emitter Rear Contact (PERC) modules. The limited availability of domestically made cells restricts the market for Indian panel manufacturers, especially since government projects under the Ministry of New and Renewable Energy's schemes require cells to be produced locally under the Domestic Content Requirement (DCR).

Indian cell manufacturers have been prioritising cell production for in-house module assembly or for export, particularly to the U.S. market, further intensifying the shortage of cells available for domestic projects. The demand for domestic mono PERC solar cells has surged due to government utility tenders and subsidy schemes, but domestic manufacturing capacity has not kept pace, creating a significant gap between supply and demand. As a result, the cost of domestic solar cells is now two to nearly three times higher than that of imported A-grade cells, even though the wafers used in cell manufacturing are sourced internationally. This disparity poses serious challenges for Indian producers.

Industry experts suggest that expanding production capacity is crucial, as p-type mono PERC cells (M10 size) remain the dominant technology in India, with n-type cells starting to gain ground. The industry is gradually transitioning towards advanced technologies like TOPCon, which can be upgraded from mono PERC, and HJT, which requires a different cell process altogether. This shift highlights the need for technological advancements and increased investment in cell manufacturing capabilities to keep pace with the evolving market.

Despite the challenges, TOPCon technology is on track to dominate the global solar sector in the near future. The rapid transition to TOPCon is so significant that PERC technology is expected to be completely replaced in the coming years. According to a report by Business Research Insights, the global TOPCon solar cell market is projected to reach USD 68.49 billion by 2032, up from USD 7.35 billion in 2021, growing at a compound annual growth rate (CAGR) of 22.49 percent during this period. As TOPCon rises, global PERC capacity is anticipated to decline to less than 25 percent by the end of this year, with complete phase-out expected by 2028.

As nations worldwide pursue sustainability, solar energy remains at the forefront of renewable energy development. With increasing emphasis on efficiency and economic viability, TOPCon technology is set to lead the charge in driving sustainable progress.