LONGi Vs QCells - Which panels are better for you?

Find out the differences between LONGi and QCells and which panels are more suited to your home.

LONGi Solar and QCells are both tier 1 solar panel manufacturers and are considered very reputable companies in the solar industry. However, when you compare between two specific models, one from each manufacturer, you can spot the differences and make an educated decision on which solar panel to choose for your project.

After detailed analysis it is determined that both QCells solar panels and  LONGi solar panels are very similar in terms of solar panel power capacity, dimensions, operating conditions and efficiency. The price of the solar panel could be the major driver in selecting one from the two.

This article explores the difference between the panels based on power, product and system certificates, efficiency, and dimensions of the solar panels. 

It's important to note that there was a patent dispute between the photovoltaic manufacturers in 2019. In March 2019, QCells filed a patent infringement lawsuit in both Germany and the United States, against Longi and two other solar manufacturers. According to QCells, its three competitors have illegally used its patented technology in their products. In June 2020, the Regional Court of Düsseldorf, in Germany, ruled in favor of QCells and issued a court order to recall their solar modules affected by the patent dispute. Since the other manufacturers did not fully comply with the court order, the court has ordered them to pay fine. 

LONGi Solar

LONGi Solar was established in 2000 and has an annual operating revenue of 8.41 billion USD. The solar company is headquartered in Shaanxi, China and supplies more than 30 GW of high efficiency solar wafers and modules worldwide, about a quarter of global market demand. LONGi produces monocrystalline silicon wafers and modules and delivers solutions for distributed and ground mount power systems.

LONGi Solar – LNG-LR6-600PH0350M

LONGi Solar modules are highly efficient and reliable, they are proven to have an average cell efficiency of 20%. The most advanced module manufacturing technologies are applied to get lower LCOE (Levelized Cost of Energy), excellent performance at Light Induced Degradation (LID) and to ensure the power generation and investment revenue for customers. 

The solar panel comes with system and product certifications including IEC 61215 and IEC 61730. The solar panels have a 12-year product warranty covering materials and processing and a 25-year linear power output warranty. Annual degradation is less than 2% in the first year (light induced degradation losses) and 0.55% from year 2 to 25. 

Figure 1: LONGi Solar warranties (source - data sheet)

The solar panel has a length of 1,762 mm and a width of 994 mm. The panel weighs 19 kg and is 35 mm thick. The solar frame can withstand snow load of up to 5,400 Pa on the front and wind loads of up to 2,400 Pa on the rear side. The cell orientation is 6 parallel and 2 series. The Junction box is IP67 rated, and the output cable size are 4mm2 in cross section. 3.2mm coated tempered glass is used to protect the solar cells.

The solar panel has an operational temperature between -40°C to +85°C. The power output tolerance is 5 W, the maximum system voltage is 1,500 VDC and maximum series fuse rating is 20 A. 

Figure 2: Solar panel size (source - data sheet)

QCells

Hanwha QCells is a major manufacturer of photovoltaic solar cells. The company is headquartered in Seoul, South Korea, after being founded in 1999 in Thalheim, Germany. QCells has a module manufacturing capacity of 12.4 GW per year. As a vertically integrated company, QCells ensures the strictest standards of quality for PV systems across the entire supply chain. 

QCells - QMaxx-G2-350

QCells solar modules are efficient and reliable, they are proven to have an average cell efficiency rate of over 19.5%. QCells uses innovative all-weather technology to optimize yield under low light conditions while enduring high performance by using anti LID technology and Hot spot protection. The solar panels can withstand a snow load of 5,400 Pa and a front wind load of 4,000 Pa. The solar panels undergo damp heat testing for 2,000 hours and thermal cycle testing for 600 hours.

The solar panel comes with complete system and product certifications including IEC 61215 and IEC 61730. In addition, the solar panels are also certified under IEC61701 and IEC62716. The solar panel has a 12-year product workmanship warranty and 25-year linear power output warranty.

Figure 3: QCells solar warranties (source - data sheet)

The solar panel has a length of 1,740 mm and a width of 1,030 mm. The panel weighs 19.9 kg and is 32 mm thick. The Junction box is IP67 rated, and the output cables are 4mm2 in cross section. 3.2mm coated tempered glass is used to protect the solar cells.

The solar panel has an operational temperature of -40°C to +85°C. The maximum system voltage is 1,000 VDC and maximum series fuse rating is 2 0A. 

Figure 4: QCells solar panel size (source - data sheet)

Comparison

Product and system certificates

SpecificationLONGi 350WpQCells 350Wp
IEC61215 (Design and Qualification approval)YesYes
IEC61730 (Global standard for PV module safety)YesYes
ISO9001 (Quality management system)YesYes
ISO14001 (Environment management system)YesYes
OHSAS18001 (Occupational health and safety)YesYes

Both solar panels have similar certifications.

Product warranty

Both solar panels have similar warranties. 

Electrical characteristics

SpecificationLONGi 350WpQCells 350Wp
Product warranty1212
Liner power performance warranty2525

The above electrical characteristics are observed at standard test conditions (STC) of 1,000 W/m2, cell temperature of 25°C. It can be observed LONGi has a higher efficiency than QCells solar panels at STC.

Mechanical characteristics

SpecificationLONGi 350WpQCells 350Wp
Solar cellsMono crystallineMono crystalline
Module dimensions (mm)1762 x 994 x 351740 x 1030 x 32
Weight (kg)1919.9
Glass3.2 mm coated tempered glass3.2 mm coated tempered glass
Encapsulant materialEVAEVA
Back sheetWhiteWhite
Frame35 mm anodized aluminum body35 mm anodized aluminum body
J-boxIP67 ratedIP67 rated
Cables4.0mm24.0mm2
ConnectorMC4MC4

Both solar panels have similar mechanical characteristics. 

Maximum ratings

SpecificationLONGi 350WpQCells 350Wp
Operational temperature-40° to 85°C-40° to 85°C
Maximum system voltage1,500 Vdc1,000 Vdc
Max series fuse rating20 A20 A
Snow load5,400 Pa5,400 Pa
Wind load2,400 Pa2,400 Pa

The maximum system voltage in LONGi is 1,500 Vdc compared to 1,000 Vdc of QCells. Other maximum ratings are similar. 

Verdict

Both QCells and LONGi Solar are tier 1 manufacturers. Tier 1 solar manufacturers use the best grade of silicon to produce solar cells. Higher the silicon grades the better the solar panel will perform. The solar panels from both suppliers are similar in many ways, however the key differences can be summarized as follows:

  1. Both offer similar product warranty and liner power performance warranties
  2. LONGi has better efficiency at STC
  3. LONGi has a higher maximum system voltage 

The price of the solar panel can be used as a key decision making factor as most if not all other parameters seem very similar between both brands of solar panels. 

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