Demand for silicon crystal & wafer: Linton Technology estimated the current global silicon crystal and silicon wafer production volume to be 3 billion kg and 60 billion pieces yearly, respectively. (Photo Credit: Linton Technology) 
Technology

Solar – Made In The US: TaiyangNews Physical Conference Session 2 In Collaboration With EUPD & RE+

Leading Global PV Equipment Makers Discuss Opportunities & Challenges For Vertically Integrated PV Manufacturing Ecosystem In The US

Rajarshi Sengupta

  • Session 2 of the TaiyangNews physical conference on “Solar – Made In The US” explored the latest technology offerings from multiple PV production equipment makers, including those for ingots, wafers, and cells

  • Participants included silicon ingot equipment maker Linton Technologies, cell fabrication tools supplier Leadmicro, and metallization paste provider Solamet

  • The conference concluded with a brainstorming panel discussion focused on emerging ingot/wafer and cell production projects in the US

Recently, the US has experienced a resurgence in PV manufacturing, fueled by the Inflation Reduction Act (IRA). The announcement of 250 GW of new or expanded solar manufacturing capacity across 23 states is expected to attract $14 billion in investment.

To navigate untapped international markets like the US, global PV equipment manufacturers – specializing in ingot, cell, and module production – shared insights into their latest technologies and market dynamics at the recent physical conference, “Solar – Made in the USA.” This event featured a brainstorming panel discussion and was held on the sidelines of the RE+ 2024 exhibition in Anaheim, CA, co-hosted by EUPD, RE+, and TaiyangNews on September 9, 2024.

In the 2nd of a total of 4 sessions at the conference, Dr. Zhixin Li, CEO and CTO of Linton Technologies Group, presented his company’s latest production equipment for crystal growth and wafer slicing. Beginning with a brief introduction to the company, Dr. Li discussed the KX series CZ crystal growers. This crystal-growing tool, featuring an impressive 42” hot zone and equipped with over 800 kg of silicon discharge, can produce more than 5 tons of output every month at a growth rate of 2.0 mm/min. Dr. Li stated that the company sold over 8,000 units of this tool, equivalent to a capacity of 120 GW, in 2023.

He emphasized that with the current rate of PV installation worldwide, 3 billion kg of crystals and 60 billion silicon wafers are produced each year, supported by more than 50,000 crystal growers and 100,000 related jobs. He noted that a typical 130 µm thick wafer, featuring 2 major dimensions – 182 x 182 mm and 210 x 210 mm – is priced between $0.15 and $0.25 each. Dr. Li explained that the latest KX380PV crystal grower, with its 42” crucible, can produce more than 10 times the number of monocrystalline ingots compared to 15 years ago. The presentation concluded with an overview of the latest wafer-slicing technology offered by the company, along with a discussion of the downward cost trend of mono-wafers compared to multi-wafers, driven by advancements in mass production.

Turnkey tool solution: Leadmicro provides turnkey tool solutions, including ALD, PECVD, and thermal boron diffusion, for TOPCon mass production. (Photo Credit: Leadmicro)

CTO of Leadmicro, Prof. Jerry Liao, highlighted his company's achievements in developing turnkey lines for TOPCon cell production. A leading Chinese supplier of PV cell production equipment, Leadmicro offers a range of tools, from traditional vacuum systems like boron diffusion to cutting-edge technologies such as atomic layer deposition (ALD) for front-side passivation. For rear-side passivation, the company supplies PECVD tunnel oxide, PECVD intrinsic poly, and PECVD SiNx systems.

Prof. Liao shared the company's journey for PECVD TOPCon technology development - starting from a pilot line to mass production with a collaboration with Tongwei Solar, where they resolved equipment and process challenges by May 2021, achieving TOPCon cell efficiency of 24%. This was followed by a 1 GW mass production trial, during which the yield rate improved from 30% to 97% by June 2022. At the multi-gigawatt factory scale, the company addressed challenges like process safety and manpower training. For efficiency improvement, the selective emitter (SE) process was implemented but later replaced by laser-assisted firing technology in April 2024, added Prof. Liao.

After describing a brief evolution of PE-TOPCon technology, Prof. Liao introduced Leadmicro’s latest 5th generation ZR5000X2 series PECVD ToxPoly tool, which allows consecutive tunneling oxide and intrinsic polysilicon deposition, followed by in-situ doping in a single tube. The tool features tunable in-situ doping and can reduce the polysilicon layer's thickness, simplifying mass production.

After discussing rear-side passivation, Prof. Liao detailed advancements in front-side passivation tools. Starting with the 5th generation tube-type KF15000 series ALD tool in 2021, the company overcame mass production hurdles by 2023 with the 7th generation KF20000 series. He stated that the latest 8th generation KF20000S series can handle 17,000 TOPCon cells (182 mm) in a single-load configuration and up to 22,000 cells (182 mm) in double-load mode. To address module-level losses from cutting the cells, Leadmicro also developed tools for TOPCon half-cell processing - KF20000S/D-H series ALD, ZR5000-H series PECVD, and XH10000B-H series diffusion systems.

Staying ahead: Solamet emphasized the importance of new metallization paste development in sync with the latest high-efficiency cell structure, such as PV3NL series TOPCon paste compatible with the LECO process. (Photo Credit: Solamet)

The next presentation was delivered by the CTO of Solamet Electronics Materials, QJ Guo. He shared insights on the importance of paste development in keeping pace with rapidly evolving cell technologies. Mr. Guo noted that using silver (Ag)-based paste on both the front and rear sides of TOPCon cells has resulted in significant metallization-induced recombination losses on front-side passivation, constraining cell efficiency. To address this challenge, Solamet developed the PV3NL series paste, optimized for use with the laser-enhanced contact optimization (LECO) process. He emphasized that the paste’s specialized chemistry minimizes damage to front-side passivation layers during the selective opening of pyramid tips via LECO, enhancing open-circuit voltage (Voc) and delivering excellent ohmic contact. The PV3NL paste applied through the LECO process has delivered an efficiency boost of 0.2% to 0.6% compared to baseline silver-aluminum (Ag-Al) paste for nearly 20 Chinese customers of Solamet in Q4 2023.

According to Guo, the emerging TOPCon back contact (TBC) technology presents unique challenges when selecting suitable metallization pastes. Aluminum (Al)-based pastes cannot be used to contact the p-poly region due to the polycrystalline structure, while finding the right balance between recombination and contact resistivity in the p-region using Al-free paste is particularly difficult, especially for thinner p-poly layers. To tackle this issue, the paste manufacturer is exploring optimized solutions through 2 different technology routes: fire-through and non-fire-through methods.

To address High-cost concerns with HJT cell structure, Solamet has developed HJT pastes with reduced silver (Ag) content, incorporating silver-coated copper powders to maintain efficiency. The PV43A-TX series offers a range of low-ag-content options.  

Panel discussion

Moderated by TaiyangNews’ Managing Director, Michael Schmela, the panel deliberated on “How to Speed Up Ingot/Wafer & Cell Production Projects?” Participants included Todd Templeton from NorSun, Terry Jester of Highland Materials, Stefan Quist from American Ingot, and Adam Tesanovich of Talon PV.

Terry Jester from Highland Materials provided an overview of the company's upcoming polysilicon plant in Tennessee, which will produce up to 8 GW of silicon annually, expanding to 11 GW in the second phase. She emphasized the importance of cost competitiveness and CapEx optimization for commercializing new technology.

Stefan Quist, engineering director from American Ingot, clarified that it is still in the planning stages for an ingot-making plant in a large warehouse, where it currently has 250 MW of PV modules.

Norwegian wafer-making company, NorSun’s Todd Templeton appreciated the US government’s present incentive schemes, unlike Europe’s extremely challenging environment for wafer manufacturers. The company is now focusing on building a wafer-making factory in the US and securing a domestic supply chain.

Adam Tesanovich of Talon PV shared insights into the opportunities and challenges faced by emerging high-efficiency cell manufacturers in the US.