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Longi Solar solar panels review

Overall Rating From 10 Reviews:

Longi Solar solar panels review

Average Customer Rating:
( 4.60 / 5 )

Longi Solar is a Chinese company that is a tier one manufacturer of solar panels.  They only produce monosilicon panels and may be the largest monosilicon solar panel manufacturer globally.  Their panels come with a 10 year product warranty.  They also have a 25 year product warranty that is considerably better than average.  Longi Solar does not have an office in Australia and so the importer of the panels will be responsible for their warranties.

Longi Solar Production

Longi Solar was the world's fastest growing solar manufacturer in 2016.  They produced 2.34 megawatts of panels during that year, but claimed to have 5 gigawatts of module production capacity at the end of 2016.  Despite this, they only produced they produced just 1.259 gigawatts of panels in the first half of 2017, which was 11% less than in the second half of 2016.  This is considerably less than I would have expected from a company with their claimed capacity, but it seems their output is still at a level for the company to be a new member of the "Silicon Module Super League";  which is the group of now 7 companies that account for around half the world's solar panel production.

To date, most of Longi's production has been used in China, but the firm has been expanding into overseas markets and their panels are becoming more common in Australia.

Company History

Founded in 2000, by 2007 Longi boasted 100 tonnes of monosilicon production capacity - enough for approximately one gigawatt of solar modules these day. In 2007, it was likely less, as silicon ingots were still being cut into the thicker "toast" slices instead of the thinner "sandwich" type silicon ingot loafs they do today. These days, ingots are cut so thin, there's only approximately half a gram of silicon in each solar cell.

Longi shipped 2.5 gigawatts of silicon wafers in 2014, which are slices of silicon ingot before they are turned into solar cells.  2014 was also the year Longi stopped producing silicon ingots and wafers exclusively and expanding into solar panel manufacturing by buying Lerri Solar.

After acquiring Lerri Solar, which had been making solar panels since 2007, Longi continued to produce panels under the Lerri name until early in 2017 when the company rebranded as Longi Solar.  Longi may have held off on the rebranding to ensure panel reliability was up to par before associating the Longi name so closely with them.

From 2014 to 2016 Longi expanded rapidly.  Fortunately this success did not lead to them becoming arrogant and developing a Longi 'tude.  Their current 2017 production does not look like it will exceed 2016 production and it remains to be seen if Longi will resume its rapid growth.

Longi Headquarters

Longi is headquarted in Xian, or Xi'an; which located in Shaanxi Province, but Longi says on its website this city is located in the neighboring Shanxi Province.  Somehow the company confused Shaanxi and Shanxi when writing about themselves in a foreign language.  I can't imagine how that happened.

Longi is headquartered in Xi'an rather than further south near Shanghai where the majority of the world's solar panels are made because they began operations as a silicon manufacturer.  Monosilicon production requires a great deal of electrical energy, so they were founded in an area with access to cheap coal power.  Fortunately, China is taking steps to reduce their coal use and one of them is a massive build out of solar capacity.

Overseas Production

In addition to their Chinese factories, Longi is expanding production overseas.  Longi is constructing a factory in India with the ability of manufacturing 500 megawatts of solar panels annually.  The facilility will the situated in the Special Economic Zone (SEZ) in Sri City in Andhra Pradesh.  The factory will employ 1,000 people, which is a significant number for a 500 megawatt plant these days, but as wages are lower in India compared to China, it's not unusual to be hiring more staff than they would back on their home turf.

Longi has also purchased a facility in Malaysia capable of 500 MW of solar panel capacity a year when complete. The plant will ship in silicon ingots, slice them into wafers, produce solar cells and panels, and then melt all the waste silicon to produce new ingots on site.

Longi Makes Monosilicon Exclusively - No Polysilicon

There are two types of silicon used in the production of solar cells -- polysilicon and monosilicon.

Polysilicon is comparatively easy to make.  The molten silicon is poured into a mold and allowed to cool.  It's quick, easy, and there's little in the way of waste.  Its disadvantage however, is it is made up of multiple crystals of silicon; which impacts on the efficiency of solar cells.

Monosilicon is significantly more difficult to produce and consequently more expensive, but the process results in a single large crystal of silicon, enabling solar cells be more efficient.

Longi only makes monosilicon and is the world's largest producer -- at least in respect to ingots.  They own a massive number of specialised slow cookers called crucibles that bake and rotate at the optimum rate to produce cylindrical ingots of silicon using the Czochralski process.  Ingots used for solar cell production are typically 10 to 20 centimeters across.

The crucibles, which reach temperatures of 1,425 degrees Celcius, are usually made from quartz which has a melting point of 1,713 degrees Celsius.

Longi's Vertical Integration

As Longi produces silicon ingots, wafers, solar cells and solar panels, they are considered a vertically integrated company.  While this provides the company a secure supply of silicon, there is potential that by making the company larger, it becomes more cumbersome and less able to react to sudden changes in solar technology and the market.

Monosilicon = Efficient Panels

As monosilicon enables panels to be more efficient in converting sunlight to electricity than polysilicon, Longi Solar panels have reasonably high efficiencies. Their 60 cell panels, which are likely to be used on Australian rooftops, have efficiencies ranging from 17.4% to 19%.

Longi is a participant in China's Top Runner Program, which is a government scheme with a goal of boosting the efficiency of Chinese solar panels.

Efficiency Record For Mass Produced PERC Cell

Just a few days ago Longi announced they had achieved a new cell efficiency record for mass produced PERC monocrystalline cells of 22.43% (which was subsequently bettered by a competitor just a few days later).  While this is cell efficiency only, panels made from these cells won't perform quite as well, but it is still an impressive development.

Risk Of A Monosilicon-Only Approach

With a sole focus on monosilicon and owning so many dedicated monosilicon crucibles means Longi is potentially running the risk being saddled with a great deal of outdated expensive equipment if there are significant declines in the cost of silicon production using other methods.  However, as solar production is expanding very, very quickly; even if more economical methods do appear, old and new technologies could coexist for a significant period.

Longi Performance Warranty - Better Than Average

Most tier one solar panels at the lower end of the pricing range only guarantee around 80% of their originally rated power after 25 years.  But Longi promises their standard panels will still produce at least 83.1% of their original output after this time and their PERC panels will provide at 84.8%. 

With a little luck, other lower cost tier one panel manufactuers will feel confident enough in their engineering to bump up their performance warranties to being them in line with Longi's.


Longi panels are tier one and so should be reliable.  As a result I would not have a problem with installing them on my roof.  They will also appeal to people who are interested in panels that should lose little in capacity over the years, but don't want the expense of purchasing premium panels.

While many companies have run into financial difficulties after rapidly expanding, Longi's financial position appears reasonably sound.  While I don't have any solid evidence, I suspect they will be around for a longi time.  I can feel it in my gut.  Specifically, my longi intestine.

Rating Comments Name State Postcode

Bought From: Raw Electrical Qld Pty Ltd Review Date: 10 November 2018
John QLD 4350

Bought From: Helioenergy Review Date: 2 November 2018
Douglas NSW 2122
We had 6 Tigo optimizators installed to 6 panels that may have bee effected by shading - appears to be working fine.
Bought From: Space Solar Review Date: 31 October 2018
Peter VIC 3172

Bought From: Essential Solar Review Date: 27 September 2018
Anon VIC 3155

Bought From: Essential Solar Review Date: 16 September 2018
Paul VIC 3040

Bought From: Energus Pty Ltd Review Date: 27 August 2018
Alleyne NSW 2530

Bought From: Essential Solar Review Date: 13 August 2018
Ian VIC 3658

Bought From: UV Power Review Date: 10 August 2018
David QLD 4069
It is early days (not even a month in) but they are generating lots of juice (22x 300W panels, producing 28kWh on a sunny July Brisbane day). They look the part, so far so good..
Bought From: Positronic Solar Review Date: 19 July 2018
Chris QLD 4074
Longi Solar is performing much better than what I was expecting. Almost all the Tier 1 panels manufacturer give 80% efficiency after 25 years but Longi Solar give 87.7% after 25 years. I bought it purely on their reputation globally, they are also the largest Mono Crystalline panels manufacturer in the world. Their panels looks great with black frame. I am very happy with my decision.
Bought From: Essential Solar Review Date: 15 November 2017
Shazma VIC 3064

Longi Solar has 1 solar panel in our database

Model Type Size PTC Performance Ratio Californian Approved
Longi Solar