The TaiyangNews High Efficiency Solar Technologies 2024 conference devoted day 1 to TOPCon technology
Manufacturers and industry experts see it staying put as the workhorse for the next few years
There is further scope for improvement on the materials and processes front, which the industry is already working on to bring down prices, but not at the cost of efficiency
The global solar PV market officially has a new mainstream cell technology, TOPCon or Tunnel Oxide Passivated Contacts. Thanks to various technical advancements, it has already become state-of-the-art, having displaced PERC. However, today’s solar technology landscape is vibrant with 2 other technologies - heterojunction (HJT) and back contact (XBC) – in mass production. Perovskites and tandem aren’t far behind either.
So, where do these technologies stand today, in terms of their progress and costs, especially as the PV industry braves overcapacity-related challenges? To wrap up 2024, TaiyangNews decided to address these concerns in a 4-day event High Efficiency Solar Technologies 2024 From TOPCon & HJT to XBC & Tandems: innovating for Better and Lower Cost Solar Cells & Modules.
Spread across December 2 and 3, and December 10 and 11, this annual flagship conference of TaiyangNews brought together stakeholders from across the PV industry to see where we go from here.
The first day was naturally dedicated to TOPCon, the current workhorse of the industry. The keynote speaker on day 1 of the conference, Head of PV at CRU/Exawatt Alex Barrows, shared his thoughts on the PV cost, price and technology outlook. He reflected on the challenges the global PV industry is facing with overcapacity leading to unsustainable pricing. Rising prices for raw materials like silver and aluminum could further strain manufacturers, as will labor and depreciation costs. Silver, for instance, is currently in deficit and the status quo is unlikely to change over the next few years. There could be a potential small decline in supply over the next 5 years while demand grows.
For the market to return to a sustainable position, ‘polysilicon prices may need to climb in the future,’ he explained while pointing at Daqo New Energy and GCL selling polysilicon below cash cost. Glass manufacturers are in no better position. Prices may slightly reduce further as older facilities shut down, but unlikely to drop below current levels. As prices for key materials rise, it will further increase costs for module manufacturers, thus impacting the downstream market as well.
Overall, Barrows sees industry consolidation, production discipline and price rebounds as necessary for the sustainable operation of the PV industry.
In terms of technology, the keynote speaker reiterated the general belief that TOPCon has surpassed PERC and will dominate the market for some time, if the capacity expansion plans of the various manufacturers were any indication. The integrated manufacturing cost for TOPCon has reached parity with PERC and is now even headed lower.
For heterojunction (HJT), Barrows said that though it enjoys efficiency advantages, the technology is not likely to reach cost parity with TOPCon in the near future, unless there are aggressive cost-downs or a jump of 2.5% absolute efficiency improvement. Hence, it will likely remain a niche technology. But, the question to consider is what will follow TOPCon: back contact (BC) or tandems?
The longer it takes for tandems to become commercial products, the more likely it is to see a widespread transition to XBC.
Sharing the company’s TOPCon solar technology development at the conference was JA Solar’s Technical Pre-Sales Projects Manager Djamel Eddine Mansour. JA uses its proprietary Bycium+ cell technology for its modules. Bycium+ is now in its 5th generation with BCM5.0, having reached 26.80% cell efficiency, up from 25% efficiency in 2022.
In the latest version, it deploys screen-printed silver contact on both sides of the cell. What is even more exciting, said Mansour, is that this doesn’t yet include the integration of the newest innovations at JA Solar like edge passivation or zero busbar technologies to further enhance performance.
Mansour shared that laser fire technology boosts cell efficiency by 0.2% to 0.4%, and module power by 5 W to 10 W, by improving silver paste contact. JA’s use of a non-destructive laser half-cut process followed by effective edge passivation also enhances cell efficiency by 0.19% and module power by 6 W, he added.
At the module level, Mansour said that the manufacturer addresses the CTM (cell-to-module) geometrical and optical and electrical losses by optimizing wafer sizes and cell configurations. For instance, innovations such as the M10R wafer have enhanced modular power. Half-cell passivation and zero-busbar (0BB) further enhance module power. He claimed that the 0BB increases optical gains with a 3 W to 5 W improvement.
This approach also reduces material costs and energy loss as it leads to fewer microcracks, which is due to the lower welding temperature and smaller localized stress. It also lends better environmental attributes to the module, both in terms of carbon reduction in manufacturing and at the materials end, according to him. The right polymer combination has its advantages too in terms of cell protection from moisture.
A strong proponent of the n-type TOPCon technology, JinkoSolar plans to continue its focus on this technology as its mainstream product till at least 2027, according to the company’s future strategy, aligned with the global development of n-type monocrystalline. After 2028, the industry is expected to enter mass production of tandem cells with an expected efficiency of around 33%.
Sharing the company’s 2025 product outlook at the conference, JinkoSolar’s Product Manager Leo Cong said that the company, using ME technology, targets to increase solar cell efficiency to around 27% by 2025. Under its main technology route HOT 4.0, it targets to increase cell efficiency by up to 28% from early next year.
From 2025 onward, the solar PV manufacturer plans to move to 210R for its new products using a 48-cell configuration for residential, 54- and 66-cell for commercial and industrial (C&I), and 66-cell for utility-scale products under its Tiger Neo series. The three advantaged products will also be designed using dual-glass with higher hail resistance to withstand 55 mm hail impact, high wind load resistance, and high fire rating class, catering to various market needs, such as the US.
For its upcoming Tiger Neo 3.0 TOPCon solar module with up to 670 W output and 24.8% efficiency, JinkoSolar plans to use its patented n-type TOPCon technology including HCP, MAX.
Orders for this module series will be accepted from Q4 2025, starting with small scale, and going to large-scale and utility-scale in Q1 2026.
Reflecting on the in-house TOPCon technology improvements as the company turns into a 100% TOPCon manufacturer, Astronergy’s Product Solution Manager Sibin Yang said its strategy is to stick to TOPCon as the dominant technology for the next 3-5 years, going up to TOPCon 5.0. By then, the manufacturer could also possibly be looking at BC & HJT.
For the current crop of ASTRO N solar modules, Astronergy uses the TOPCon 4.0 generation with laser-induced firing. It ensures the contact between the metal and the silicon wafer while reducing the damage to the passivation layer. It also makes use of the POML technology, an upgrade of the rear poly-Si passivation technology. All of these features increase cell efficiency.
The use of a light-redirecting film enables full reflection working at a 120° angle, leading to a 2 W increase in power on the front. Yang said this reduces back shading by 30% and improves energy yield by 0.5% and mechanical performance by 3% to 6%. In addition, high-transmittance glass would enhance optical absorption.
The broad wafer size standardization to 182 mm and 210 mm sizes is enabling the market to grow with higher power output and efficiency modules. Moreover, the transition to rectangular wafer sizes of 192 x 182 mm and 210 x 182 mm has also lowered overseas shipment costs, added Yang.
Astronergy’s latest ASTRO N8 module promises a power output of up to 720 W, using the 210 x 210mm configuration with 66 cells for the utility-scale segment.
Solar cell metallization supplier Solamet Materials Science’s Technical Director Zinan Zhang shared the company’s innovative metallization solutions that improve n-TOPCon efficiency and cost-optimization.
In 2021-2022, manufacturers used a homogenous p+ emitter for TOPCon cells, which led to a manufacturing efficiency of up to 25%. It increased over the years to reach 26% with the transition to LDSE and SE with LECO. Since Q2 2024, the efficiency exceeded 26% with the help of non-SE and LECO.
Zhang stressed that fine-line printing and low solid content rear-side pastes are the 2 mature and effective solutions for TOPCon cost reduction as these approaches reduce silver use. 0BB is also being used to lower silver consumption.
Uniformity in particle size and shape directly impacts paste performance since large particles or irregular shapes can disrupt the paste flow and application uniformity. He gave an example to show how blending silver powders of varying sizes improves flow characteristics.
He explained, “By optimizing the ratio of different silver particle sizes, the solid content, viscosity, and sintering density of the silver paste are balanced, thereby enhancing fine line printability and reducing grid line resistance.”
Solamet’s research also looked into the benefits of structured passivation layers, improving cell performance even in mass production as these reduce recombination and improve carrier lifetimes.
The use of silver nevertheless makes solar production expensive. The industry has been exploring various measures like thinner grid lines and advanced paste formulations to bring down its usage, Zhang added.
Solar PV equipment manufacturer LAPLACE calls itself a pioneer in the space in terms of TOPCon cell technology for mass production. LAPLACE’s Director of Technology, International Business Unit, Josua Stückelberger claimed that the company’s equipment and process have led to the highest TOPCon solar cell efficiency of 26.89% at the R&D level.
For the new mainstream technology TOPCon cell production, LAPLACE supplies a variety of equipment barring wet tools and metallization. The introduction of improvements such as double-loading facilitates higher throughput and reduced costs. Its proprietary coated quartz tubes extend lifetimes by 6 to 9 months, thus bringing down operational costs, added Stückelberger.
As it diversifies into BC technology, Stückelberger shared that LAPLACE is ready with solutions to help its TOPCon clients integrate this and other next-generation technologies as well. Implementation for XBC requires the use of LPCVD for the deposition of both the tunnel SiOx and polysilicon layers which its equipment is fully compatible to accomplish. Some of this equipment is already delivered and operating successfully, he added. In addition, the company is now expanding its product offerings by including laser tools in its portfolio to offer a complete solution for XBC.
Almost all the tools from its TOPCon technology can be reused in the XBC process after some rearranging and equipment upgrades, thus ensuring cost control during the transition.
The Global Sales Director of specialty polymer manufacturer HIUV Jitin Rai Khanna started his presentation with the announcement of the company expanding its manufacturing footprint to India. HIUV is expected to establish cooperation with local partner in India in 2025 to serve the local market.
At the conference, Khanna talked about HIUV’s module encapsulation solutions for TOPCon based on the various tests it conducted. It is the co-extruded EPE films that are becoming the standard and these do away with the need for any additional padding on the edges, achieving a lamination yield of up to 100%, according to Khanna.
Additionally, dual-glass EVA solutions reduce costs and increase efficiency. However, for TOPCon solar cell encapsulation, Khanna considers the combination of EPE and EVA as the most optimized one, both from a cost and a performance point of view.
At the conference, Khanna also introduced the company’s new co-extrusion EXP film-P507S product that brings cost benefits through reduced use of POE and also provides stable performance.
Panel discussion
TaiyangNews Managing Director Michael Schmela opened the panel discussion to talk about the cost and development trends for today’s solar technologies.
CRU/Exawatt’s Alex Barrows said manufacturers are already taking steps to lower their costs in times of stress on their profit margins due to ASPs being lower than the production costs. The overcapacity is likely to continue unless some players exit the market. For now, the option with them is to use lower-cost materials. However, the big fish will have the next 5 years on their mind; hence, they can be expected to continue to invest in R&D to become future-ready.
JA Solar’s Djamel Eddine Mansour agreed as he discussed his company’s expansion plans. For JA Solar, he said, the production is not limited to China alone as the company expands to Vietnam and the US. There is a strategy that JA is following now even when it comes to technology. For now, TOPCon is the priority for the Chinese group, but BC and tandem are on the horizon.
LAPLACE’s Josua Stückelberger is confident of the PV industry’s resilience and strength to overcome this phase as he said that there are enough big players to push new technologies on the R&D level. There is still scope for improvement on the technology side of things, for instance at the metallization and the process level.
The discussion on TOPCon will continue on December 10, 2024, which will be day 3 of the TaiyangNews High Efficiency Solar Technologies 2024 Conference. TOPCon Solar Technology Part II will have a keynote address from Fraunhofer ISE and presentations from several leading manufacturers. A panel discussion will follow with the central idea being ‘what more can be done to improve TOPCon?’
Day 4 of the event will then focus on BC technology. If you haven’t already registered for the 4-day conference, register for Days 3 & 4 for free here.