LONGi
LONGi Green Energy is headquartered in Xi'an, China. It started in mono silicon wafers and is now one of the world's largest module makers by shipments. Its current Hi-MO 9 and Hi-MO X10 modules use back-contact cells (HPBC 2.0), which move all the metal contacts to the rear of the cell.
- Headquarters
- China
- Positioning
- Mid-marketEnterprise
- Official website
- www.longi.com
Who it suits
Space-limited, hot rooftops that need the most power per square metre and lower losses under partial shade.
Overview
Who LONGi is in 2026
LONGi Green Energy is headquartered in Xi'an, China. It began in mono silicon wafers and expanded into cells and modules. In 2025 it was again among the largest module makers in the world by shipments. Like most Chinese manufacturers, LONGi reported a loss for 2025, a result of industry-wide oversupply and falling module prices.
How back-contact differs
Most panels sold in 2025–2026 use TOPCon cells with thin metal fingers on the front. LONGi took a different route: its HPBC 2.0 cell moves every contact to the rear, so nothing on the front blocks light.
- Hi-MO 9: a large 144-cell module (2382 × 1134 mm, about 33.5 kg), up to about 670 W and 24.8% efficiency, glass-glass. Built for factory roofs and ground mounts.
- Hi-MO X10: the same HPBC 2.0 cell in formats designed for home and commercial rooftops, including all-black versions.
Reading the warranty and heat numbers properly
Hi-MO 9 carries a 12-year product warranty and a 30-year linear power warranty. These are two different promises. The product warranty covers a module that fails because of materials or workmanship (a burnt junction box, glass that breaks by itself, delaminating encapsulant). The power warranty covers output falling below a stated curve: for its new BC modules LONGi states about 1% degradation in year one and about 0.35% per year after that. A claim needs IV-curve measurements as evidence.
The temperature coefficient (Pmax) of Hi-MO 9 is −0.26%/°C. A worked example: at noon in Laos, cells on a metal-sheet roof reach 60–65°C, about 35–40°C above the 25°C test condition. At −0.26%/°C the module loses roughly 9–10% of its nameplate power; a module at −0.30%/°C loses about 11–12%.
Who it suits
LONGi suits mid-size and large customers whose roof area is limited and who want the most kWp from it, or roofs with partial shade from posts, water tanks or a neighbouring building. LONGi states that the HPBC 2.0 cell is designed to limit hot-spot heating under partial shade.
Strengths
- Back-contact cells have no metal fingers shading the front, so the same roof holds more kWp than with lower-efficiency modules.
- The −0.26%/°C temperature coefficient of Hi-MO 9 means less power lost during hot Lao middays.
- A large maker that has appeared on Tier 1 lists for years, which matters because a 30-year warranty is only worth as much as the company still there to honour it.
- A cell design that limits hot spots helps on roofs with partial shade from antenna masts or water tanks.
Things to know before choosing
- Back-contact is LONGi-specific. If a module fails years later, a different brand with matching electrical values may be hard to find for the same string, so keep one or two spares for larger systems.
- Hi-MO 9 weighs about 33.5 kg and is 2.38 m long. It needs two people to lift and a roof structure and wind-load check first; smaller formats usually suit house roofs better.
- Models and warranty terms differ by market. Ask for the warranty document that applies in this region and check serial numbers with the Thai seller before ordering.
- The module industry is consolidating and many makers are losing money. Large makers remain the safer bet, but keep purchase documents and serial numbers complete for future claims.
Using it in Laos
What we commonly see on sites:
- Dry-season dust (November–April): red dust from dirt roads and mines settles on modules quickly. Back-contact modules still need washing. Set a cleaning schedule with soft water and a soft brush, never a pressure washer. See our cleaning and inspection checklist.
- Heat and humidity: glass-glass modules resist humidity and PID degradation better than backsheet modules, but leave at least 10–15 cm of air gap under the modules so heat can escape.
- Transport: modules come from Thailand on pallets. Check for broken glass and cell cracks on delivery before signing, because provincial roads shake loads badly.
- Claims: warranty claims go through the Thai seller. Keep serial numbers, flash-test sheets and the Voc/Isc readings taken at handover as evidence.
A good fit for factory, hotel and office roofs in Vientiane where roof area is too small for lower-efficiency modules.
Compared with alternatives
JinkoSolar Tiger Neo 3.0 and JA Solar DeepBlue 5.0 are TOPCon modules with similar peak efficiency in large formats and high bifaciality, so they fit better on ground mounts or white roofs that reflect light onto the rear. Choose LONGi when roof area is the constraint or there is partial shade. Trina Solar Vertex S+ is a good alternative for house roofs that need a smaller, lighter module.
Product lines
- Hi-MO 9
- Hi-MO X10
Solutions that use this brand
On-grid Rooftop SolarRooftop solar for homes, shops, offices and schools, sized to your daytime load, with a zero-export option.
Commercial & Industrial SolarEngineered solar for factory roofs, carports and ground mounts, from a few hundred kWp up to megawatt scale.
Hybrid Solar with Battery StorageHybrid inverter and LiFePO4 battery to keep power on through outages and evening brownouts, and to store daytime solar for the…
Off-grid Solar for Remote SitesStand-alone power for schools, health posts, farms, work camps and telecom sites with no grid or a weak one.
Solar Water PumpingPump from boreholes, streams or ponds with sunlight for orchards, rice fields, farms and village water supply, without fuel or a…FAQ
Is back-contact really better than TOPCon?
For power per square metre and partial shade, back-contact has the edge. On an open, unshaded site with reflective ground, bifacial TOPCon produces similar energy. We model the yield of both for your roof before you choose.
What do the 12-year and 30-year warranties actually mean?
The 12 years are the product warranty: a module that fails from a manufacturing fault is replaced or repaired. The 30 years are the power warranty: if output falls below the stated curve, the maker compensates. Neither covers damage from bad installation, lightning or people walking on the modules.
Can we add LONGi modules to an existing system of another brand?
Yes, as a separate string or on another MPPT input of the inverter. Do not mix brands or power classes in one string, because the weakest module drags the whole string down. We check MPPT voltage and current limits before proposing it.
All brand names and trademarks belong to their respective owners. Mention does not imply official partnership unless explicitly stated. Products are sourced through legitimate distribution channels.
Send us a floor plan or a few photos of the site
We’ll come back with a few questions, then a first design. The first consultation is free, in Lao, Thai or English, on WhatsApp or our Facebook page.