TaiyangNews_Report_Heterojunction_Solar_Technolog

Authors: Shravan K. Chunduri, Michael Schmela The Next Big Thing in Solar Cell/Module Manufacturing? Heterojunction Solar Technology 2019 EditionWe maximize energy output. Superior Heterojunction solar cells with efficiencies over 24% combined with outstanding SmartWire Connection Technology delivers record-breaking 480W* bifacial solar modules. Manufactured on Meyer Burger’s HELiA ® cell coating and SWCT™ connection platforms. Meyer Burger takes you to new energy levels. meyerburger.com/HJT meyerburger.com/SWCT *verified 410W by CEA/INES + 17% albedo = 480W RECORD-BREAKING SOLAR MODULE: Engineered by the technology leader MBT_Inserat-480W_210x297_EN_18_RZ.indd 1 14.08.18 14:28Heterojunction Technology 2019 | TaiyangNews 3 We maximize energy output. Superior Heterojunction solar cells with efficiencies over 24% combined with outstanding SmartWire Connection Technology delivers record-breaking 480W* bifacial solar modules. Manufactured on Meyer Burger’s HELiA ® cell coating and SWCT™ connection platforms. Meyer Burger takes you to new energy levels. meyerburger.com/HJT meyerburger.com/SWCT *verified 410W by CEA/INES + 17% albedo = 480W RECORD-BREAKING SOLAR MODULE: Engineered by the technology leader MBT_Inserat-480W_210x297_EN_18_RZ.indd 1 14.08.18 14:28 © TaiyangNews 2019 All rights reserved. The text, photos and graphs in this report are copyrighted (cover photo credit: Meyer Burger). TaiyangNews does not guarantee reliability, accuracy or completeness of this report s content. TaiyangNews does not accept responsibility or liability for any errors in this work. Publisher: TaiyangNews UG (haftungsbeschraenkt) Montsalvatstr. 15 80804 Munich, Germany www.taiyangnews.info TAIYANGNEWS ALL ABOUT SOLAR POWER Click on the chapter or the sub-chapter you want to explore. Contents 01 Introduction 6 02 • Basics of HJT • Process Flow of HJT • Recent HJT Developments • Market Players 10 03 HJT Processing • Wafer Processing • Cell Processing ○ Wet-Chemical Processing ○ Core Layer Deposition ○ TCO Deposition ○ Metallization - Screen Printing - Plating 18 • HJT in Module Making ○ Interconnection - Bonding Based Interconnection - SmartWire Connection Technology (SWCT) Advertisers: • Meyer Burger p. 2 • Longi p. 5 • GS-Solar p. 7 • Ardenne p. 9 • Jinergy p. 13 • SNEC p. 21 • Heraeus p. 26 04 Performance of HJT Devices 36 • Cell Efficiencies • Power Output at Module Level • HJT System Level 05 Commercialization and Capacity 40 06 Costs 43 07 Limitations 44 08 Future Advancements in HJT 44 09 Conclusions 45 10 Interviews 46 • Jinergy • Meyer Burger4 TaiyangNews | Heterojunction Technology 2019 Executive Summary Heterojunction technology (HJT) has been making big progress in recent years, though more quietly as PERC has been dominating the headlines in the solar tech space. There is a small but increasing number of companies working with the support of research centers and equipment makers on HJT technology that holds the efficiency world record for silicon solar cells for years – and since Aug. 2017 at 26.6%. There are several reasons for the renewed and growing interest in HJT. For one, it is HJT’s high efficiency potential after PERC is evolving into the new cell standard, and the industry’s focus on further improving efficiency to satisfy the asks for higher and higher module power ratings. Then, it is the promise of very low LCOEs for HJT-based PV systems. HJT comes with the fundamental advantage of the highest bifaciality. Moreover, there is the low-cost production potential of heterojunction technology that needs a much lower number of process steps than traditional solar cells. The report covers the different HJT processing steps from wet-chemical treatment, deposition to metallization at the cell level, also providing a brief overview on equipment of the key players. As to the major change in wet chemistry, offered by all leading wet-chemical bench suppliers, the production of HJT cells requires a higher degree of cleaning than other cell technologies, such as standard BSF or even PERC. The most crucial step in producing HJT cells is deposition. The first part of the deposition – applying doped and intrinsic amorphous silicon layers – is accomplished using plasma-enhanced chemical vaporization deposition (PECVD) tools. Longtime PECVD cell processing equipment leader Meyer Burger, as well as Archers and former thin-film equipment producer GS Solar are offering PECVD tool platforms for this core deposition process. INDEOtec is in the process of developing an innovative machine platform that enables deposition of doped intrinsic amorphous silicon layers on both sides in one machine. Applying transparent conductive oxide (TCO) layers, mostly with sputtering tools, completes the deposition step. Taiwan’s Archers Systems is promoting Reactive Plasma Deposition (RPD), as an alternative to sputtering for applying TCO layers. However, indium tin oxide (ITO) is the unanimous choice of material for TCO, at least as of now. Other materials are under investigation. Several established equipment makers – including Von Ardenne, Meyer Burger, Singulus – and others are offering equipment for R commercial design modules with impressive power ratings up to 348 W for 60 cells and up to 413 W for 72 cells have been achieved. This report also provides an overview on important topics related to HJT, such as commercialization, costs, major limitations and possible future advancements. The report concludes with 2 interviews from pioneers in the new HJT phase – with Jinergy CEO Liyou Yang, who believes ‘24% HJT production efficiencies are in sight.” And with Meyer Burger CTO Gunter Erfurt, who emphasized that ‘HJT technology is ready.’ t Enjoy reading our Heterojunction Solar Technology Report 2019 Shravan K. Chunduri Head of Technology, TaiyangNews shravan.chunduri@taiyangnews.info +91 996 327 0005 Hyderabad, India Michael Schmela Managing Director, TaiyangNews michael.schmela@taiyangnews.info +49 173 15 70 999 Munich, Germany 6 TaiyangNews | Heterojunction Technology 2019 Power conversion efficiency is the most important performance characteristic of a PV device, especially at the cell level. Japan’s Kaneka is the top seed with a record efficiency of 26.63% for a commercial- size crystalline silicon solar cell achieved in August 2017. This remarkable conversion efficiency has been attained by adding an interdigitated back contact (IBC) cell structure to the heterojunction cell architecture platform. This technology fusion is also the basis for previous world records – 26.33% cell efficiency, attained again by Kaneka in September 2016, and 25.6% set by another Japanese company, Panasonic Corporation, in early 2014, breaking its own earlier HJT record of 24.7%. Apart from the fact that HJT has been setting world record efficiencies in the PV industry for decades and has promising development possibilities, the technology also has several other advantages – a short production process with fewer steps, low processing temperature, low degradation and a lower thermal coefficient. 1. Introduction HJT World Record Cell Efficiencies Over Last 5 Years 26.63 26.33 25.6 24.7 20 21 22 23 24 25 26 27 Kaneka (BC HJT) Kaneka (BC HJT) Panasonic (BC HJT) Panasonic (HJT) Aug. 2017 Sept. 2016 April 2014 Feb. 2013 EFFICIENCY (%) Source: © TaiyangNews 2019 HJT – mostly a true HIT story: HJT has been part of most of the crystalline silicon-based world record cell efficiencies (top). As the graph from Panasonic graph shows (bottom), the company improved its HIT technology consistently from about 20% in 2000 to 25.6% in 2014. Panasonic efficiency progress Source: Panasonic8 TaiyangNews | Heterojunction Technology 2019 However, despite the advantages of using HJT, it is still not widespread in the commercial space. Sanyo, which originally developed the technology, owned a few important patents for HJT. It was bought by Panasonic in 2010, and as a result, Panasonic remained the single source for HJT solar modules commercially until the recent past, which has limited spreading of technology know-how. In addition, HJT production cannot be achieved by simply inserting extra production equipment into manufacturing lines for standard cells. It requires a completely different manufacturing setup at the cell level and quite a high optimization at the module level. The technology also requires a different skill set altogether. The process involves depositing thin-film layers, the key to its high efficiency – meaning it also requires thin-film deposition expertise. All of these factors hindered widespread adaptation of the technology in commercial production, thus confining it to being a subject of interest for researchers. In recent times, the technology has been gaining momentum, when HJT started attracting a lot of attention from PV manufacturers looking for higher efficiencies. Standard cell technologies, even when upgraded to passivated emitter rear cell (PERC) production, are quickly getting closer to their threshold. HJT is also offering a second chance for former thin-film PV makers to use their expertise and equipment. Several PV makers, in addition to equipment vendors, have established pilot lines, and research centers have been demonstrating technical and commercial feasibility of the technology. Swiss equipment maker Meyer Burger, the technology leader in this field, even thinks the HJT era has started already. And indeed, in Dec. 2018, the tool supplier finally announced its first big deal for a 600 MW integrated HJT/SWCT cell/module line from an undisclosed non-Chinese company. Still, while many industry players that TaiyangNews has interviewed believe HJT could be important to the future of the PV industry, there are still doubts on the further development path of the solar cell technology – so the jury is still out “when” or perhaps even “if” HJT will conquer a large share in the market. High power ratings: One of the major advantages of HJT is its high output power resulting from its superior passivation. Source: GS-Solar Heterojunction Technology 2019 | TaiyangNews 9 For one thing, HJT is just one of the candidates competing to become the next generation technology for commercial PV production. And committing to fully overhauling production facilities, a requirement for taking the HJT plunge, might be seen as too much of an investment risk in the high stakes world of cell manufacturers concerned about their financial bottom lines. But given HJT’s potential for high cell efficiencies, module power ratings and superior yields, which are even higher when factoring in the very high bifacial gain, the technology may prove a good bet for companies willing to take the leap of faith to differentiate themselves from the competition. Seeing the light: While HJT has been around for many decades, only now is it starting to see the ‘commercialization’ light beyond the pioneer in that space – Panasonic. Companies such as GS- Solar from China or Hevel from Russia, are building big systems using the technology. Source: GS-Solar Source: Hevel SCALED-UP PERFECTION IN PVD COATING FOR HIGH-PERFORMANCE CONTACT LAYERS XEA|nova - horizontal wafer coating system for front and backside deposition. www.vonardenne.biz10 TaiyangNews | Heterojunction Technology 2019 HJT primarily addresses one issue associated with both standard production and many advanced cell architectures. Metal contacts formed in most of the approaches are highly recombination-active and cause losses. This can be avoided by electronically separating contacts from the absorber by insertion of a wider band-gap layer. Implementing this change is basically what HJT is all about. The cell architecture results in very high open-circuit voltages without the need for any patterning techniques. 2.1 Basics of HJT The most important attribute of HJT is that it is a fusion of wafer-based solar cell technology and thin- film PV, taking the best features of each. It has the excellent absorption properties of standard silicon wafer-based cells and the passivation characteristics of thin-film amorphous silicon. Unlike standard crystalline silicon solar cells, which are homojunction devices, meaning the p-type and n-type layers of the semiconductor materials are formed on the same base material, heterojunction cells are made by fusing two different kinds of materials. 2. Overview Fusion: HJT cell architecture is a fusion of wafer-based solar cell technology and thin- film PV, as shown in this schematic. Source: Meyer Burger Walter Fuhs first proposed HJT structure of fusing a-Si and crystalline silicon Yoshihiro Hamakawa from Osaka Transfomers fabricated and patented first HJT cell. It suffered from high interface states, resulting in low Voc and FF Sanyo replaced microcrystalline intrinsic layer with thin a-Si film, which resulted in 15% efficiency Sanyo made substantial breakthrough by inserting intrinsic microcrystalline silicon layer between crystalline silicon wafer and doped a-Si. Patented the approach Sanyo patented device structure of sandwiching crystalline substrate between intrinsic and oppositely doped a-Si films, which is nothing but its famous HIT structure DEVELOPMENT PHASE 1974 1985 1989 1990 1996 Sanyo started offering HJT module under brand name HIT with cell and module efficiencies of 16.4% and 14.4% respectively based on 5-inch wafers formats EPFL/CSEM, Switzerland Prof. Ballif thesis on HJT cells CEA/INES, France set up HJT Lab-Fab Meyer Burger (formerly Roth ENEL in process of setting up more than 200 MW line in Italy; Meyer Burger received order from non-Chinese company to set up integrated 600 MW HJT cell continued with 5-inch wafer format in production INDUSTRIALIZATION PHASE 2010 2013 2014 2016– 2017 Old technology, new interest, impressive progress: While HJT is a four-decade old technology, it’s high-efficiency potential is attracting attention. There has also been a lot of technology development progress, including successful adaptation to a 6-inch wafer format.