LONGi Solar Panels – ESE Review


Jack Ayre

Cut your electricity bills

Generate your own electricity with a solar PV system

With a new solar setup, including a solar battery, you can drastically reduce your electricity bill

On This Page

LONGi Solar Panels In Brief:

LONGi is the biggest solar panel maker in the world, using manufacturing plants in China, India, Vietnam and Malaysia. It puts significant resources into research and development, and has broken many world records for panel efficiency.

It only fabricates monocrystalline panels, unlike some other manufacturers. This technology is considered by experts to be superior, and the way forward for the solar PV Industry. Top efficiency, slow degradation, high power output, mean that LONGi solar panels are among the best on the marketplace.

LONGi solar panels come with an industry standard warranty of 12-years on solar panel products. The power output warranty is 25 years.

So LONGi is a major “best buy” choice for homeowners who want to invest in a solar array for whatever reason: to reduce energy costs, embrace a greener lifestyle or charge their EV.

LONGi Company Overview:

LONGi Solar was founded in 2000 as Xi’an LONGi Silicon Materials Corporation. It soon gained a reputation for superior solar PV products. By 2017, financial media source Bloomberg named it as a Tier One module manufacture company which made LONGi the most financially secure and bankable solar manufacturing company in the world, a position it retains to date. It was also the fastest-growing and by 2021 had overtaken all other Chinese solar companies to become the largest photovoltaic panel manufacturer in the world.

LONGi employs some of the most advanced manufacturing capabilities in making its solar panels, so is consolidating its lead over its competitors. In 2022 its annual revenue climbed by 48.3% to $12.5 billion (£9.98 billion) so it is truly a giant among renewable energy manufacturing companies.

LONGi Solar Panel Specifications

LONGi offers three ranges of residential solar panels, the Hi-MO 4 Series, and the Hi-MO 5 Series and the new Hi MO 6 Series. It deploys advanced techniques to ensure that its offerings are among the best on the market. These include monocrystalline chips, gallium doping, closer panel alignment, low degradation and higher power output.

Why Monocrystalline Panels?

Formerly solar panel manufacture was split between two technologies:  polycrystalline and monocrystalline. Polycrystalline was cheaper but monocrystalline was more efficient. Now most of the high-end companies are concentrating on monocrystalline products. LONGi does not make polycrystalline panels. With manufacturing costs coming down, the price advantage that polycrystalline technology formerly traded on is being eroded. LONGi’s decision to concentrate only on the most efficient energy delivery has proven to be the correct one for longer term market dominance. 

Gallium Doping

In 2020 LONGi applied Gallium Doping to its new panels, instead of the previously used Boron technology which was prevalent with other brands.  This technology was developed by LONGi Solar in collaboration with Shin-Etsu Chemical Company. Power generation losses due to degradation are a known issue for all solar panels: basically, they age, and produce lower amounts of electricity the older they get. The trick is to reduce these losses to a minimum.

LONGi solar panels lead the field with low degradation rates. The company guarantees that their monocrystalline panels will degrade by a mere 0.55% per year and 0.45% per year for the bifacial modules. The average industry degradation rate is 0.7% per year. So LONGi panels will outperform most others significantly during their lifespan. A LONGi panel will be delivering nearly 85% of the original power at the end of a 30-year term.

Smart Soldering and Close Alignment Between Cells

If the cells that make up a solar panel can be aligned more closely and have multi-busbar (MBB) connections between them, electrical output will be raised. LONGi deploys its own proprietary smart soldering and MBB technology to achieve very close spacing between cells, with an efficiency of more than 0.3% over competitors using conventional MBB methods of panel construction.


The three series each offer an “all black” option, rather than the conventional blue with aluminium frames that comprise most rooftop solar installations. Now customers have a choice of conventional-looking panels or perhaps a different aesthetic which might be more attractive for their roof array. The Hi-MO 6 series also offers an “Artist” collection of panels in different colours.

Hybrid Passivated Back Contact (HPBC) Cell Design

The ground-breaking new Hi-MO 6 series are the first panels ever to feature a Hybrid Passivated Back Contact (HPBC) cell design. This unique new cell design improves power output and is expected to become a market-leading technology.

Environmental Considerations

LONGi has long been in the forefront of an environmentally-conscious manufacturing and supply chain. They have integrated many leading concepts into their supply chain management system, such as green design, green manufacturing, green construction, green recycling and reuse, and green product life-cycle management. The company has been working with their suppliers, manufacturers, logistic solution providers, wholesalers, customers, and recycling partners to effectively reduce energy waste and pollutant emissions throughout the entire value chain and keep emissions down over the products’ complete life-cycle. Their panels are also packaged in a minimalist, eco-friendly manner to minimise waste.

Hi-MO 4 Series – Hi-MO 4 and Hi-MO 4M

The Hi-MO 4 series is one of the few types of solar panel which uses gallium-doped silicon cells which increases the solar panel’s resistance to degradation. This means the amount of power the panel will produce will remain higher because of a 0.55% per year degradation rate over a long period, than most other panels which have a typical annual degradation rate of 0.7%. 

These solar panels also offer a 12-year product warranty which is in line with most of the options on the market. LONGi offers a long-term performance guarantee: at the end of 25-years the installed modules will still produce up to 84.8% power output.

The key difference in the M designation products is that they are specifically designed for residential rooftops, while the other products are more oriented towards commercial and industrial arrays. Please note that this is just a convenient categorisation from LONGi depending on the roof area available.


Hi-MO 4 series solar panel key parameters:

  • Monocrystalline PERC gallium-doped silicon cells
  • 350W to 380W Power rating
  • 20.9% maximum panel efficiency
  • Half-cut cell technology with 9 busbars (MBB)
  • Standard 166mm M6 wafer
  • 12-year product warranty
  • 25-year performance warranty
  • 84.8% remaining power after 25-years

Hi-MO 5 Series – Hi-MO 5 and Hi-MO 5M

The Hi-MO 5 series is LONGi’s latest offer in the market and with a slightly improved solar panel efficiency it can offer customers more power whilst only taking up the same amount of space on the roof. 

LONGi have also increased the working current within the panels to around 13amps (from 11amps in the Hi-MO 4m series) which is better suited to the mainstream string inverters that are now on the market.

Hi-MO 5 series solar panel key parameters:

  • Monocrystalline PERC gallium-doped silicon cells
  • 475W to 540W Power rating
  • 21.3% maximum panel efficiency 
  • Half-cut cell technology with 9 busbars and smart soldering
  • Larger 182mm M10 wafer
  • 12-year product warranty
  • 30-year performance warranty
  • 84.9% remaining power after 30-years


Hi-MO 6 Series

LONGi new generation HPBC cell technology is a step-change in the mass production of high-efficiency cells and continues to lead solar technology. The efficiency of LONGi HPBC cells is more than 25.0%. The efficiency of the PRO version is even better and its HPBC cells output is more than 25.3%.

This is one of the highest efficiencies currently available, and is superior to that of competitors’ products that are using N-type cells. The Hi-MO 6 series uses a new P-type Hybrid Passivated Back Contact (HPBC) cell design, giving superior performance in all kinds of conditions.

The Hi-MO 6 series panels are subdivided into four types: Explorer, Scientist, Guardian and Artist models, which offer a slightly-different flavour of advanced photovoltaic panels so the buyer can pick which suits their objectives most closely. Explorer is the basic HPBC panel design. Scientist offers maximum efficiency and low degradation. Guardian contains integrated smart panel-level optimisers. Finally, Artist offers panels in a selection of unique colours.

Hi-MO 6 Series Key Parameters:

  • Monocrystalline HPBC cells
  • 410W to 600W Power rating
  • 22.8% maximum panel efficiency
  • Half-cut cell configuration with HPBC cell technology (MBB)
  • Large 182mm M10 wafer
  • 15-year product warranty
  • 25-year performance warranty
  • 88.9% power remaining after 25 years

Pros and Cons


  • Monocrystalline panels deliver more energy
  • Low degradation over lifetime
  • Top global manufacture
  • Good value for money
  • Ecological packaging with low waste


  • LONGi is introducing a new N-type next generation panel which may supersede the Hi MO 4-5 series
  • LONGi does not have a UK office so the support comes from partners rather than directly from the manufacturer
  • Guarantee is slightly inferior to the 25-year product and performance warranties offered by the premium brands, Panasonic and LG

LONGi Solar Panel FAQs

What roof types are LONGi modules suitable for?

LONGi modules are suitable for most roof types (flat/pitched roof, steel, tile, etc.). Your installation company will perform a roof survey, assessment of the roof structure and design an appropriate PV system for your particular roof.

How does LONGi ensure its solar panel systems can maintain sustained high energy yields for 25 years?

The use of a high-efficiency monocrystalline PERC cell made of M6 gallium-doped silicon wafers and the selection of more reliable double-glazed module packaging ensures that the 30-year power degradation of the modules is not greater than 15%. The special cooling air duct design alleviates the loss of energy yield due to structure cooling.

What is the payback time on LONGi Solar Panel products?

The payback period varies, depending on the roofing condition, installation position, local weather and sunlight availability as well as utility tariffs. An industry rule of thumb is that payback time is often around eight to eleven years in the UK currently, but this is just an estimate and will vary with your particular situation.

LONGi Solar Panel Summary

LONGi are the leading solar panel manufacturer in the world. Their offering must be amongst the best for efficiency, resistance to degradation, power output and value-for-money. Most householders would want to put them on their short list when looking at which solar photovoltaic system to deploy on their residence.

On This Page

Cut your electricity bills

Generate your own electricity with a solar PV system

With a new solar setup, including a solar battery, you can drastically reduce your electricity bill


Cut electricity bills

Generate your own electricity to reduce your bills


Less carbon

Reduce your overall carbon footprint and impact on the environment


Sustainable home

Making more use of renewable energy sources makes a greener home

Born in North West England, Jack kicked off his career in the insurance arena, dealing with claims for three years. Always up for a challenge, Jack leapt out of his comfort zone and embarked upon 5 years of excitement with the military.

Working for the Ministry of Defence, Jack specialised in counter-terrorism which took him to places such as Dubai, Oman, Iraq, Norway and Bahrain. During this period he worked with various Governments implementing strategic operations to prevent terrorism.

After travelling around various countries Jack increasingly came across various forms of solar from large solar farms to domestic solar panels. From here Jack took a keen interest in all things solar and started reading about the technological capabilities with a view to entering the industry after his career in the Ministry of Defence.

Once home after 5 fruitful years, Jack had 3 months leave in which he immersed himself in a solar crash course and got applying for jobs within the solar sector. He came across ESE Solar, a long-established forward-thinking company whose head office was only a stone’s throw away from him. He picked up the phone to see if there were any vacancies and within a week had a successful interview and obtained a full-time job, starting in the technical team.

Within the first few months, Jack onboarded in various online courses during work and social hours to speed up his knowledge of all things solar. Due to his strong work ethic and thirst for knowledge Jack was promoted to Head of Technical at ESE Solar. He currently leads the team and oversees the product development of new technologies within the company alongside assisting where necessary on their maintenance department.

Here's what our customers say about us

flexi-orb logo
Google logo

Get Your
FREE Quote