Overview
The LONGi Hi-MO X10 Scientist HPBC 2.0 Bifacial 645W (LR8-66HVD-645M) is LONGi’s flagship N-type module for high-output systems. It pairs HPBC 2.0 back-contact cells with the N-TaiRay process and a 0BB (zero busbar) front side. The result is more usable area per cell, lower resistive loss, and a panel face without the silver gridlines you see on standard modules.
Suitable for residential, commercial, and utility-scale installs, and rated for an operating range of -40 °C to +85 °C.
Cell technology
- HPBC 2.0 — second-generation hybrid passivated back contact. All electrical contacts sit on the rear, so nothing on the front shades the cell.
- N-TaiRay — N-type wafer with LONGi’s TaiRay coating process. Lower light-induced degradation than P-type cells, and better behaviour above 25 °C.
- 0BB (zero busbar) — conventional silver busbars are replaced with finer interconnect wires. More uniform current collection, less cell-to-cell variability, cleaner panel face.
Output
- Up to 645 W nominal power
- About 30 W more than a comparable conventional 144-cell M10 panel
- Bifacial back side — adds yield where mounting and ground reflectance allow
Behaviour in real conditions
- A+ anti-shading rating — when a chimney, vent, or row shades part of the panel, the unshaded cells keep producing instead of cutting the whole string
- Hotspot-resistant cell layout
- Reduced micro-crack risk under thermal cycling, which backs the long warranty
Electrical (STC)
- Maximum power (Pmax): 645 W
- Module efficiency: 23.88%
- Open-circuit voltage (Voc): 49.62 V
- Short-circuit current (Isc): 16.46 A
- Voltage at MPP (Vmp): 40.88 V
- Current at MPP (Imp): 15.78 A
- Power tolerance: 0 to +3%
- Max system voltage: DC 1500 V
Mechanical
- Cells: 144 (6 × 24)
- Dimensions: 2382 × 1134 × 30 mm
- Weight: 28.5 kg
- Front glass: 3.2 mm tempered, coated
- Frame: anodised aluminium
- Junction box: IP68 rated
- Operating temperature: -40 °C to +85 °C
- Fire rating: IEC Class C
Warranty
- 15-year product warranty (materials and workmanship)
- 30-year linear power-output warranty
Best fit
This panel suits projects where watts-per-square-metre matters: roof-constrained residential, commercial rooftops, and ground-mount utility arrays where the bifacial back side can earn its keep. If you have plenty of roof space and the constraint is price-per-watt, a lower-tier mono module will be cheaper.
FAQs
What makes the LONGi Hi-MO X10 645W different from standard panels?
Three things: HPBC 2.0 back-contact cells (no front-side gridlines), the N-TaiRay process for better temperature behaviour, and 0BB interconnects in place of conventional busbars. Together they produce around 30 W more output than an equivalent conventional 144-cell M10 module.
Is the LONGi 645W bifacial panel suitable for residential use?
Yes, provided the roof can fit a 2382 × 1134 mm module. The panel was designed for commercial and utility-scale projects, but if you want maximum yield per square metre of roof and don’t mind paying for it, this is one of the highest-watt residential-suitable panels currently available.
How efficient is the Hi-MO X10 645W?
23.88% at STC, putting it near the top of mass-production silicon panels available today. For context, an entry-level mono panel typically sits around 20-21%.
What does bifacial technology actually buy you?
The back side also produces power, by capturing light reflected off the surface below the panel. On a dark roof the gain is minor; on a light-coloured ground-mount or commercial flat roof it can be 5-15% additional yield. It’s only worth paying for if the install will actually see rear-side light.
How durable is the Hi-MO X10 panel?
3.2 mm tempered front glass, anodised aluminium frame, IP68-rated junction box, and an operating range of -40 °C to +85 °C. The 30-year linear power-output warranty means LONGi expects measurable output at year 30.
What warranties come with the panel?
15 years on materials and workmanship, plus a 30-year linear power-output warranty.
How does it cope with partial shading?
Better than a standard panel — A+ anti-shading rating. The back-contact layout means a shadow on one cell hurts that cell’s output, not the whole string. It is not a substitute for module-level optimisers if the site has heavy intermittent shade.
What are the headline electrical specs?
Pmax 645 W, Vmp 40.88 V, Imp 15.78 A, Voc 49.62 V, Isc 16.46 A. System voltage rated to DC 1500 V.
Is the panel safe for long-term use?
Yes. Hotspot-resistant cell design, reduced micro-crack risk under thermal cycling, IEC Class C fire rating, and a 30-year output warranty backing the longevity claim.
Where is the Hi-MO X10 645W best used?
Commercial roofs and ground-mount utility arrays first, then residential installs where roof space is tight and per-watt output matters more than total system cost.
No products in the cart. 
Reviews
There are no reviews yet.