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TOPCon can perhaps safely be called the only one in the solar spectrum to have had superfast growth as a dominant technology to date. Not just that, it is on its way to become the standard PV technology for the world, replacing current workhorse PERC. But then, there are other high efficiency solar technologies that are quickly gaining traction as well like the heterojunction (HJT), back contact and next generation technologies.
It is all these technologies that TaiyangNews is exploring in our annual flagship event, the 4-day High Efficiencies Solar Technologies Virtual Conference to see how these have grown so far and where they go from here.
Day 1 of the conference on December 13, 2023 was dedicated to TOPCon solar technology.
It started with a keynote from Bloomberg New Energy Finance (BNEF) Solar Analyst Youru Tan sharing the latest updates on the global PV supply chain with a focus on the demand and supply situation. According to BNEF projections, up to 415 GW of solar PV capacity is likely to be installed in 2023 with a 64% annual growth. However, the speed of growth is expected to decline with 511 GW—representing 24% annual improvement—to be installed in 2024. Further up, the market will accelerate by an average of 11% annually till 2030.
While demand has been growing around the globe, solar PV manufacturing is growing even faster, putting pressure on module prices. Polysilicon capacity has expanded with new and upgraded facilities coming online this year. Expecting over 2.7 million tons of global polysilicon capacity in 2024 –enough to produce over 1 TW of PV products – Tan warns the oversupply to bring down polysilicon prices to $6.0/kg in 2024. Manufacturers with no cost advantage may end up shutting shop in such a scenario.
It will have a ripple effect that could pull down module prices as well. As Tan points out, module prices have already fallen by almost 50% since the beginning of 2023 selling at $0.24/W and further down to about $0.13 towards the end of the year. BNEF forecasts that prices for typical solar modules could further drop to $0.115/W by the end of 2024.
High efficiency TOPCon module prices command a price premium over their p-type counterparts, but these have also been on a downhill slope since the beginning of 2023 due to the rapid increase in production capacity.
Another aspect that directly impacts module prices is growing inventory. China shipped 212 GW of solar cells and modules during 10M/2023, with Europe as the largest destination. There is still 60 GW to 80 GW of solar capacity in the European supply chain. Since large developers prefer to buy latest solar modules directly from the manufacturers, inventory in Europe is expected to take another year or two to be exhausted, according to Tan.
TOPCon will be the next mainstream technology in 2024, according to BNEF estimates, as it brings with it reduced production costs with improvement of materials. By the end of July 2023, BNEF tracked 192 GW of TOPCon cell production capacity, which should exceed 300 GW by 2023-end.
Currently, both TOPCon and HJT require more silver than PERC, making it the key to the pricing of next-generation solar technologies. Silver price remains dependent on the spot market, which exposes the PV industry to price volatility.
Nonetheless, despite cost pressures, TOPCon modules are increasingly considered bankable, said Tan, referring to BNEF's bankability survey for various module technologies.
One among the pioneers of TOPCon technology, JinkoSolar's Deputy General Manager of R&D Oscar Zhang talked about achieving record cell efficiencies with TOPCon. By the end of 2023, the Chinese manufacturer aims to expand the average efficiency of its flagship TOPCon module Tiger Neo to over 25.8%, while the highest cell efficiency has reached 26.8% at the R&D stage.
With further technology improvements underway, JinkoSolar will target TOPCon cell total passivated contacts cell efficiency of 26.5% in 2024, improving to 27% by 2025, according to its TOPCon efficiency roadmap. It also plans the tandem way with TOPCon, with maximum efficiency exceeding 32% by 2026.
Talking about the benefits like high reliability and stringent quality control brought about by a tight vertical integration of the PV value chain, JA Solar's Senior Manager of Product Promotion Jerry Sun shared that the company's annual production capacity will reach a total of 85 GW for ingots, wafers and cells each by the end of 2023. The annual module production capacity will expand to 95 GW, comprising 57 GW of n-type.
In various tests and actual installations, JA Solar says its star module series DeepBlue 4.0 Pro, based on n-type TOPCon technology, has been proven to show excellent reliability even under extreme conditions like heavy snowfall, hail and thermal shock. In various climatic conditions, including dry-hot and humid-hot, its n-type modules have generated higher electricity than p-type panels, for all different application segments.
Astronergy Product Manager Xuanyi Shi listed the advantages that rectangular wafers bring for TOPCon modules in terms of high module power, lower system BOS cost and optimized container space and transportation costs.
Shi pointed out that rectangular wafer modules have the same module width as the traditional square 182 wafer modules, but deliver higher power output, which effectively reduces the BOS cost in the portrait configuration.
The Chinese company's TOPCon modules—ASTRO N7 for utility-scale and ASTRO N7s for the residential segment—use rectangular wafers of the 210R and 191R configuration. The Astronergy 210R-66 module series has lower Voc compared to 182-72 series which allows 2 additional panels to be connected in a string for a 1500V system, shared Shi.
The Astro modules also adopt laser doped selective emitter, and the company is also working on laser induced firing (LIF) leading to high current density. According to Shi, LIF improves the conversion efficiency of TOPCon solar cells by 0.3% abs. compared with the optimal fired reference.
Another vertically integrated solar PV manufacturer Runergy's Technical Support Manager Victor M. Rada talked about the superior performance and reliability of n-type technology during his presentation. Along with solar cell and module production, Runergy is also into ingot & wafer, polysilicon, metallurgical-grade silicon production, all the way up to quartz mining. This integration provides customers the ease of traceability which, as Rada pointed out, is becoming a matter of concern in several markets, especially the US.
Runergy currently offers TOPCon modules for the utility segment and plans to expand its n-type offerings to industrial and rooftop solar modules with new launches in 2024. It will include n-type HJT products as well.
Even though TOPCon is the module technology of choice at present, a dominant module size and future technology pathway remain uncertain. Rada stressed that his company remains reactive to market requirements, and is ready to change/adapt to any such changes.
Nonetheless, seeing strong potential for HJT, Runergy plans to roll out HJT solar cells from H2/2024.
Solar cell metallization leader DKEM's New Technology Development Director Mike Guo talked about the company's innovative metallization pastes enabling TOPCon efficiency beyond 26.5%.
While higher Voc and FF are the driving force for high efficiency solar cells, Guo said metallization pastes are the key enablers of advanced solar cells.
He also batted for Laser Enhanced Firing (LEF) metallization to help bring down passivation etching. A game changer, this technology leads to greater than 5 mV higher Voc with LEF, he added. The technology is expected to bring value addition with its ability to support thinner polysilicon film deposition and improved reliability; the latter even makes TOPCon compatible with the glass-backsheet module configuration. The total metallization solution for TOPCon from DKEM, including the pastes for front & rear fingers and busbars, has the potential to raise the cell efficiency beyond 26.5%. The recipe optimization for bifacial poly, i.e. adapting the passivated contacts on both sides, is also in the paste maker's radar.
Hangzhou First's Technical Director Hou Hongbing addressed moisture sensitivity and the specific needs of TOPCon modules with new encapsulation materials.
While glass-glass TOPCon module configuration is a well-established one, most challenges are reported for glass-backsheet panels, according to Hongbing.
He shared that double-glass modules with n-TOPCon technology are mainly affected by PID on the front side, for which the right encapsulation type can be EPE+EVA. For the front side, where EPE is typically employed, the thickness uniformity of the POE film sandwiched between 2 EVA layers has a significant impact on the anti-PID attributes of the module. "The EP304 with ultra-thin POE layer with high thickness uniformity is shown to have excellent PID resistance in double glass configuration," according to Hongbing.
For the glass-backsheet modules under this technology, it is mainly the PID and the so-called moisture induced degradation (MID) that play spoilsport. For the latter, Hongbing said his company's TF4N POE works well as the front film. He further emphasizes that when using TF4N POE, the significance of the rear encapsulation film becomes relatively less relevant, meaning even EVA can be used.
However, Hangzhou First is promoting a new generation of acid resistant EVA film called F•RST EBISU, based on a technology that the company got exclusive license from Japan's Kyocera. This combination – TF4N POE and EBISU – on front and rear, respectively, eases the requirement for backsheets with ultra-low water vapor transmission rate (WVTR), meaning the mainstream CPC backsheet or even the transparent variant of it can be used without any concerns for degradation. Hangzhou also has a high reflectivity black backsheet for glass-backsheet TOPcon solar modules in its portfolio.
Leadmicro Chief Scientist Professor Baochen Liao shared the equipment solutions for mass-production of TOPCon cells. The company offers a range of deposition tools based on ALD and PECVD, and thermal processing tools for cell technologies. Leadmicro ventured into the TOPCon space in 2021 with a pilot line, and delivered 2 GW turnkey mass production projects in 2022.
Currently, the company is promoting the so-called PE-TOPCon 2.0 technology, in which it offers a PECVD/PEALD platform for the crux of the process of deposition tunneling oxide and n-type polysilicon. To be specific, PEALD is employed for applying silicon oxide and PECVD is used to deposit the polysilicon and for in-situ doping. The tool, called ZR series, has a throughput of 6,200 and 5,000 wafers per hour of M10 and G12 wafer sizes, respectively. The process not only diminishes the wraparound to less than 1 mm compared to rival LPCVD with significant wraparound, but also leads to high average of Voc of 725 mV. Liao also presented an overview of the current crop of products from Leadmicro for the front surface passivation and thermal processing tools used in TOPCon processing.
Fire chat
In a fire chat with the TaiyangNews Head of Technology Shravan Chunduri, JinkoSolar's Oscar Zhang shared the Chinese manufacturer's learnings in its TOPCon solar technology development journey.
One among the earliest PV companies to explore TOPCon technology, JinkoSolar is a leading supplier of these modules today, with a clear future roadmap. Over the years, Zhang shared, the manufacturer has been successful in bringing down its production cost significantly with an intensive R&D work.
The Chinese manufacturer is confident of exceeding 27% efficiency for TOPCon, which needs further R&D as it won't be possible with the current manufacturing infrastructure and processes; hence, it continues to explore the space further, even beyond TOPCon. It also remains watchful of other potential technologies including tandem, while maintaining its lead on TOPCon that's set to be the mainstream technology over the next 2-3 years, he added.
The TaiyangNews High Efficiency Solar Technologies conference will continue next week on December 19 and 20, 2023, when we further expand the discussion on TOPCon and also explore next-generation technologies, respectively. Register free for both days here.
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