LONGi

Key takeaways

LONGi belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect LONGi to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of LONGi from memory before moving on to harder problems.

Reference excerpt

LONGi Green Energy Technology Co. Ltd. (Chinese: 隆基绿能科技股份有限公司) or LONGi Group (隆基股份), formerly Xi'an Longi Silicon Materials Corporation, is a Chinese photovoltaics company, a major manufacturer of solar modules and a developer of solar power projects. LONGi is the world's largest manufacturer of monocrystalline silicon wafers and is listed on the Shanghai Stock Exchange.

History The company was founded 14 February 2000 by Li Zhenguo as Xi'an LONGi Silicon Materials Corporation, with its corporate headquarters in Xi'an, Shaanxi. It changed its name in February 2017 to LONGi Green Energy Technology Co Ltd. to better reflect its wider manufacturing scope after its acquisition of LERRI Solar, and also dropped the "Xi'an" location as part of the name. In early 2016, LONGi signed a $1.84 billion solar panel sales agreement with SunEdison Products Singapore and agreed to purchase silicon manufactured in South Korea. LONGi also took over SunEdison's Malaysian silicon plant. In early 2018, LONGi announced plans to build a new 5 GW module assembly plant in the Chuzhou Economic and Technological Development Zone in China's Anhui province, pending an internal review process, then an investment of approximately RMB 1.95 billion (US$300 million) and approximately 28 months of construction and start-up for manufacturing operations to commence. In 2023, the U.S. Department of Commerce ruled that Vina Solar, a subsidiary of LONGi was circumventing tariffs for Chinese made products. In 2024, LONGi announced plans to reduce workforce overcapacity by 30% staff reductions. In April 2024, the European Commission initiated an investigation into LONGi over anti-competitive subsidies.

Subsidiaries and acquisitions LERRI Solar Technology Co., Ltd. (a.k.a. LERRI Photovoltaic Technology, also LERRI Solar) was acquired by LONGi in 2014. LONGi Solar

Operations LONGI Silicon Materials is engaged in the research, manufacture and distribution of monocrystalline ingots. It is the world's largest monocrystalline silicon manufacturer, and has rapidly broken world solar efficiency records three times within five months. Fast Company listed Xi'an LONGi Silicon Materials one among "Most Innovative Companies 2013" "for supplying the solar industry with high-quality silicon wafers at low cost".

Business LONGi has been called the fastest growing PV manufacturer in the industry. LONGi annual revenue in 2013 was derived entirely from selling around US$330 million of mono c-Si wafers, but by 2016 that annual revenue had skyrocketed to approximately US$1.67 billion. That was a nearly 94% increase over the 2015 fiscal year, which had itself generated a revenue growth of around 61% over the year before. LONGi has manufacturing plants in Mainland China, India and Malaysia, and has acquired production facilities from other companies, including from American manufacturer SunEdison. However, Photon.Info reports that Longi Green Energy is mulling an open manufactory in the USA. Longi Silicon is a member of the Silicon Module Super League (SMSL), which had been a group of big-six c-Si module suppliers in the solar PV industry today until Longi was admitted. The other six members of the SMSL group are Canadian Solar, Hanwha Q CELLS, JA Solar, Jinko Solar, Trina Solar, and GCL. Longi Silicon has been listed on the Shanghai Stock Exchange (security code: 601012) since April 2012.

Research and development LONGi Solar, a subsidiary of LONGI Green Energy Technology, achieved in 2018 a new industry record with 23.6% conversion efficiency with its P-type monocrystalline PERC (passivated emitter rear cell) solar cells, toward which an increasing number of manufacturers worldwide are migrating. The technique involves taking a silicon wafer, typically 1 to 2 mm thick, and making a multitude of parallel, transverse slices across the wafer, creating a large number of slivers that have a thickness of 50 micrometres and a width equal to the thickness of the original wafer. These slices are rotated 90 degrees, so that the surfaces corresponding to the faces of the original wafer become the edges of the slivers. The result is to convert, for example, a 150 mm diameter, 2 mm-thick wafer having an exposed silicon surface area of about 175 cm2 per side into about 1000 slivers having dimensions of 100 mm × 2 mm × 0.1 mm, yielding a total exposed silicon surface area of about 2000 cm2 per side. The electrical doping and contacts that had been on the face of the wafer are now located at the edges of the sliver, rather than at the front and rear as in the case of conventional wafer cells, as a result of this rotation. This results in making the cell sensitive on both sides, from both the front and rear of the cell (a property known as bifaciality). As of April 2026, LONGi appears 9 times on the data table for the National Laboratory of the Rockies Best Research-Cell Efficiency Chart (cell-efficiency-data-table.xlsx), specifically in the silicon heterostructure and perovskite/Si categories.

Products P/N-type Mono-crystalline silicon wafer P/N-type Mono-crystalline ingots Bifacial solar cells

References

External links Official website

Worked examples

Example 1 — a first encounter with LONGi

Start with the simplest possible case. Write down what LONGi claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to LONGi before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about LONGi ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of LONGi

In research: LONGi appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses LONGi in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: LONGi is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chinese brands, Chinese companies established in 2006, Companies in the FTSE China A50 Index, so understanding it makes those chapters shorter.
In everyday life: Look for LONGi outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study LONGi in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what LONGi means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain LONGi out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is LONGi in simple terms?

LONGi Green Energy Technology Co. Ltd.

Why does LONGi matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study LONGi?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on LONGi.