TOPCOn Makes Inroads In India's Solar Cell Manufacturing Sector

Highlights :

TOPCon technology seems to have made its inroads in India with increased adoption of the latest technology by local solar manufacturers.
Several foreign and Indian solar makers have switched their production lines to TOPCon for better yield and lower degradation.

TOPCOn Makes Inroads In India’s Solar Manufacturing Sector

TOPCon’s Time to Shine Arrives in India

Around 2019, mono-PERC (Passivated Emitter Rear Contact) was well on its way to dominate the solar market in India, in a market that was ruled by polycrystalline modules until then. Researchers and developers had already estimated its dominance five years ago in 2014, but it took a wholesale shift to mono-PERC by leading Chinese manufacturers to force a market shift here as well. By 2022, the volume of mono-PERC stood at a whopping 160 Gigawatt (GW).

However, it has taken until 2023 for polycrystalline modules to be truly relegated to the background as even the government, through the Ministry of New and Renewable Energy (MNRE) managed ALMM (Approved list of module manufacturers) list dropped almost all polycrystalline module makers from the list earlier this year. There remain domestic manufacturers who still make and sell polycrystalline modules, mainly for low end, low cost applications and some specialised areas. These manufacturers are all from the era when domestic manufacturing was barely 8-10 GW capacity, as compared to the over 60 GW today.

Emergence of n-type TOPCon

It was mid-2022, as higher efficiency and lower costs remained the buzzwords, that references to n-type TOPCon started being made as the next big standard. By the end of 2022, when mono-PERC was still enjoying its sunny days, JinkoSolar caught market attention as it announced achieving 26.4% efficiency by employing n-type TOPCon. Meanwhile, Trina Solar had already crossed 25% efficiency for the technology by August 2022. Canadian Solar had announced mass production of n-type by mid-December 2022.

Back home in India, n-type TOPCOn surfaced, too, with India’s biggest module maker, Waaree Energies of the Waaree Group, launching n-type TOPCOn in October 2022. In 2023, most solar developers worldwide have followed suit with their own shift to n-type TOPCOn. Clearly, the days of mono-PERC are numbered.

In India, egged on by government incentives, the new wave of manufacturing has not made the mistake of going for old technology, jumping straight into n-type TOPCon technology in many cases. In the recent REI Expo, several Indian firms or firms having their business in India, like Adani Solar, Gautam Solar, Waaree, Premier Energies, Goldi Solar, RenewSys, Longi, Axitec and others, flaunted their TOPCOn solar cells and modules. On the other hand, Cosmic and Luminous already have plans to start TOPCOn production sooner in the next few months.

The Science & Commercials Of It All

The primary difference between a p-type and n-type cells is that the p-type dopes its silicon wafer with boron. It has one less electron than silicon. This cell, as the name suggests, is positively charged. Doped with phosphorus, an n-type cell has an additional electron than silicon. It makes the cell negatively charged.

Initially, the p-type rose to prominence, before the n-type began to overtake the p-type. Because n-type cells employ phosphorus, not boron, they resist boron-oxygen defects. Boron-oxygen defects impact efficiency, bringing it down. Besides, n-type cells are not impacted by light-induced degradation (LID).

At the same time, TOPCOn promises a longer life span of panels as it has lower power degradation in the first year and even in the 25 years compared to mono-PERC. This is why you might have seen panel lifespans being quoted at even 30 years or more now.

The temperature coefficient of TOPCOn solar panels is also lower than that of PERC solar panels. Thus, TOPCOn solar panels can retain efficiency even at higher temperatures.

To conclude, the advantage of n-type is that the level of degradation is relatively low. With the p-type, there is a degradation of 2.5% in the first year, whereas with the n-type, it’s about 1%, which is almost negligible. So, as a result, even though the n-type is more expensive to manufacture, as mentioned earlier, the gains end up being higher because of higher generation output, leading to an edge on that holy grail of analyst and developer excel sheets, LCOE (Levelised Cost of Energy).

TOPCon solar cell structure

Source: CEEW-CEF adaptation from Wilson et al. (2020) and Kafle et al. (2021)

In 2021, a research team at the Fraunhofer Institute for Solar Energy Systems engineered an n-type solar cell based on the TOPCOn (Tunnel Oxide Passivated Contact) modular design developed at Fraunhofer ISE with an efficiency of 26 percent.

“A silicon oxide layer with a thickness of just a few nanometres (tunnel layer) and a further layer of highly doped silicon” was applied to the cell surface, which helped improve the electrical conductivity and bring down transmission losses simultaneously.

In the same year, LONGI achieved 25.09% efficiency for its n-type TOPCOn innovation. Thus, the n-type TOPCOn technology which established its presence earlier than 2022 made it to actual production far faster, thanks to lower costs in adapting assembly lines for it.

Most of the solar cell makers Saur Energy spoke to forecasted that in the next few months, TOPCOn will be a booming market in India too, with most players planning to adopt the advanced technology.

n-type TOPCOn vs mono-PERC

For any developer, the lower LCOE and higher efficiencies are the holy grail. N-type TOPCOn claims to win on both grounds when pitted against mono-PERC.

TOPCOn and mono-PERC

As per Fraunhofer ISE Institute, efficiencies can go beyond 25% easily with n-type mono-PERC. Typically, n-type TOPCOn efficiencies are pegged at around 28.7% (in some cases, even as high as 29%), which is a clear winner over mono-PERC, which still struggles to cross 25%. When the efficiencies between mon-PERC and n-type TOPCon are compared, the verdict is clear, as the latter has at least 3% higher efficiencies when compared to mono-PERC.

Market analysts expect TOPCon and HJT to make over 50% of global crystalline silicon production capacity by 2031

Source: ITRPV (2021)

Not just that, another major advantage that n-type TOPCOn enjoys over mono-PERC is that it promises more power- regardless of the wattage, in limited land area, developers in segments like utility-scale, ground-mounted, C&I rooftops stand to gain from this technology. While the bifacial aspect for PERC solar modules is at an average of around 70%, it is 85% for TOPCOn panels. Thus, this explains why TOPCOn is a better choice for ground-mount utility projects.

Shubhra Mohanka

Shubhra Mohanka, Director at Gautam Solar, told Saur Energy that TOPCOn offers a BOS saving of 3% of the cost while it generates 5% additional power compared to mono-PERC. She added that the extra power generated through TOPCOn could help compensate for the additional CAPEX needed to shift from mono-PERC to TOPCOn.

“Many production facilities of regular mono-perc modules are switching to n-type TOPCon. Hence, very shortly, I would say in the time window of, let’s say, seven to eight months, probably 70% of the market will be captured by n-type technology, either HJT or TOPCon, p-type is going to die out.”

She also added that compared to HJT, due to the higher popularity of TOPCOn globally, the entire supply chain for the technology is in place and thus favours the larger deployment of n-type TOPCOn in India. Moreover, she said that as the scale of deployment of TOPCOn increases, the prices could go down too.

As far as the BOS is concerned, while in the TOPCOn vs mono-PERC debate, TOPCOn emerges as the clear winner in the verdict, there are cons to it, too. The TOPCOn line is more expensive to manufacture than mono-PERC.

Bharat Bhut

Bharat Bhut, Director and Co-founder of Goldi Solar, said, “If you want to move from mono-PERC to HJT, you would require 80% of the new CAPEX. So, due to the higher CAPEX needed for HJT, TOPCOn is commercially viable for solar cell and module makers. There is a 0.5% difference in the efficiency levels between TOPCOn and HJT.

In the next quarter, TOPCOn in India will be and shipped from India. By the next mid-year, more than 50% of products globally or in India will be TOPCOn.”

Surender Pal Singh

Surender Pal Singh, Chairman of Premier Energies, said his firm has already ventured into this segment, owing to its virtues. “TOPCOn is the future because the efficiency is high with the cost remaining the same. Today, in mono-PERC, we can achieve 23.3% and 23.4% efficiency, whereas in TOPCOn, the target is 24.4% and 24.5%. Premier has already ventured into this segment, and we are setting up 1 GW of TOPCOn cell manufacturing line very shortly,” he said.

What TOPCOn and mono-PERC have in common is the usage of silver paste during their making. But TOPCOn demands a higher percentage of silver during production. This is because TOPCOn employs silver paste on both sides of the cells. While this helps increase efficiency because of the bi-faciality aspect, the truth is that TOPCOn will always be more expensive to produce than mono-PERC. Yet a manufacturer does not need new machinery to make TOPCon, which can be made with the same machinery with which P-type modules are made. It, in turn, means that the production of TOPCOn does not necessitate high CAPEX.

South Asia’s biggest renewable energy event, the Renewable Energy International Expo (REI), is the place to be when you’re looking to gauge the big market shifts in the region in renewables. And this year, the messaging was loud and clear, with most firms betting on the n-type TOPCOn and unveiling this technology type.

As per most developers, we spoke during the event, this technology type will dominate in the next six to eight months.

Rahul Bhutiani

The numbers speak for themselves, with 420 to 450 GW of manufacturing capacity share being claimed by TOPCOn from a total of 600 GW worldwide.

“Moving from mono-PERC to TOPCOn is a different line and technology. The good thing for the mono-PERC cell makers is that they can use their facility and add some CAPEX to transition to TOPCOn with additional technology in the cell line. So here, the same infrastructure used for mono-perc could be used,” Rahul Bhutiani, Chief Marketing Officer of Adani Solar, told Saur Energy.

Dr. Neha Bansal Sainbhi

Dr. Neha Bansal Sainbhi, Deputy Manager (R&D), Waaree Energies said, “We have also launched the n-type TOPCOn module. It has a significant market share. It is likely to have a share of 60-70% by 2025 in India. We are all set to develop a 5.4 GW n-type TOPCOnsolar cell manufacturing capacity in-house.”

Looking Chinaward

China, the unparalleled frontrunner in the renewable energy sector, is known to set the bar within the industry, and the leader has already set the precedent for the world.

While developers have only begun to launch n-type TOPCon in India, China is already mass-producing it, with 80% of the market share being claimed by this technology.

Manufacturers in the Indian industry say that n-type TOPCOn will stabilize in the market only in six to eight months, which is when scale of economies could also be achieved, bringing down the costs in turn. China is already way past this stage. Two months ago, Chinese manufacturer GCL System Integration Technology operationalized the first phase of its 20 GW TOPCOn manufacturing unit a few months back.

Trina Solar has grabbed the opportunity with a big bet on TOPcon, shipping over 65 GW of the modules by Q1 this year with its 210 mm cells.

As far back as 2021, LONGi said it was looking to launch TOPCOn production projects in Xixian City (15 GW) and Ningxia City (5 GW), China, with production capacities of 15GW and 5GW respectively. It was among the first instances of mass production of this technology in China.

Close on the heels of this announcement, Jolywood, another Chinese manufacturer, also revealed its plan to unveil n-type bifacial modules employing TOPCOn technology, with a 16 GW TOPCOn production line in the offing.

As early as February 2023, the production capacity of TOPCOn in China touched 69.75 GW. A month later, LONGi announced it was set to add 30 GW of n-type TOPCOn solar cell production capacity. It is estimated that when 2023 closes, China’s TOPCOn production capacity will have reached 477 GW.

China’s TOPCon dominance is demonstrated with the over 17 manufacturers boasting production capacity exceeding 10 GW and higher. JinkoSolar itself touched 10 GW last year.

Sai Charan Kuppili

Sai Charan Kuppili, Technical Director (South & Central Asia) Jinko Solar, said, “Standardisation of TOPCOn has already started to take place and it will soon be completely standardized. In the next 8 to 12 quarters, TOPCOn will lead from the front. Within six quarters, you can expect HJT intervention. Currently, it is 60 GW of HJT vs 420 to 450 GW of n-type TOPCOn worldwide.”

As per a study by TrendForce, estimates for 2023 indicate that the worldwide solar panel capacity could reach an astounding 1,034 GW, marking a 64.7% increase year-on-year. Approximately 335.4 GW represents newly added capacity, predominantly driven by Chinese enterprises.

Tanmoy Duari

Most Indian manufacturers are setting their sights on n-type TOPCOn and realizing the benefits and potential expansion that partnering with Chinese firms can facilitate. Among the firsts to leverage the advantage is Gautam Solar, which partnered with Jinchen to manufacture n-type TOPCOn solar modules.

Tanmoy Duari, CEO of Axitec Energy India, said that in the next 7-8 months, 70% of the market would shift to TOPCOn. “There is a changeover happening from the regular p-type mono-perc to the n-type, either a TOPCOn or the HJT, which are competing technologies, each with their own merits and disadvantages.”

Emerging New Technologies

Successor of TOPCon & HJT- IBC?

Another emerging option with strong backing from LonGi, no less, is Interdigitated back contact (IBC) architecture. IBC boasts the highest silicon wafer-based solar cell power conversion efficiencies, surpassing those of even TOPCon or HJT. IBC solar cells require interdigitated (or striped) doping on the rear surface and only have contacts on the rear. This can be done by way of masked diffusion, masked ion implantation, or laser doping. After this, the solar cells are metallized by forming metal fingers along each diffused region.

Back Contact & TopCon

As per NREL, similar cell efficiencies to TOPCon can also be found in silicon heterojunction technology (HJT) and interdigitated back contact (IBC) technologies. HJT and IBC typically provide a measurable efficiency advantage over PERC and—depending on the specific manufacturing process being used—can be within $0.05/W of PERC manufacturing costs.

Competing Technologies

As per 2020 benchmarks, between PERC, TOPCon, and IBC, the lowest bifaciality is offered by PERC (0.65–0.80) and IBC (0.45–0.75). However, these values can be augmented over time by improving cell metallization and interconnection.

TOPCon and HJT seem to be the clear winners in this category, with 0.80–0.85 and 0.80–0.95, respectively..

HJT Next on the Cards for India?

It is amply clear by now that n-type TOPCOn in India will dominate the market over the next few years; however, in the time to come, its closest competitor should be HJT (Heterojunction Technology).

solar TOPCOn

Reliance New Solar Energy has already entered this market in India. Last year, in April, the firm signed up China-based solar cell equipment supplier Suzhou Maxwell Technology to procure (HJT) cell manufacturing lines, paving the way for manufacturing HJT cells of 4.8 GW.

Reliance will employ high-efficiency HJT of Renewable Energy Corporation (REC) Solar Holdings, a Norway-based PV manufacturer it acquired in October 2021, for its Jamnagar factory. The firm is eyeing the proposed expansion from 10 GW of HJT to 20 GW by 2026.

However, HJT, as a relatively new technology, has less trained manpower with limited backend suppliers. When compared, HJT offers greater efficiency over TOPCOn but is substantially more expensive than TopCon even now.

Meanwhile, as expected, China is already into the mass production of HJT too. It made its way into the Chinese market back in 2020.

As per a study released in May 2022, the CAPEX for manufacturing lines in India for PERC (USD 22 million/GW), TOPCOn(USD 30 million/GW) and HJT (USD 55 million/GW) are vastly differing.

Conclusion

The TOPCOn technology, after spreading through the Chinese manufacturing ecosystem, is set to repeat the story with Indian solar manufacturers to transition to advanced technology. Besides the cost benefits, the push from the Indian government through policies for more efficient solar panels is another reason that can propel the growth of this higher efficient technology.

The Ministry of New and Renewable Energy (MNRE) has already amended its norms under the Approved List of Module Manufacturers (ALMM) to allow only those solar modules with efficiencies higher than 19%. It led to the push towards phasing down polycrystalline or shifting these low-efficiency panels towards solar streetlights and solar pump segments alone.

The new start ratings programme from the Indian Bureau of Energy Efficiency (BEE) also allows the highest ratings of ‘5 Star’ only to solar panels with more than 22 percent efficiency. Union Power Minister has also said that the norms would be revised later where only the highest efficient solar panels would get 5 Star Ratings, hinting that the benchmark could go up beyond 22% in the days to come. It could pave the way for a shift of the solar cell makers to keep themselves at the leading spots.

As developers and researchers continue to augment efficiencies and the MNRE introduces new benchmarks, it is clear that MONOPerc is on its way out, making way for more evolved technologies, namely, TOPCon, HJT and IBC.

Report By-Namrata Gulati Sapra & Manish Kumar