LONGi Hi-MO 7 590W vs LONGi Hi-MO 7 620W
The LONGi Hi-MO 7 620W wins this comparison by a narrow margin. It leads in efficiency (23% vs 22.8%) and matches or exceeds on warranty (12 vs 12 years). For most residential installations, the LONGi Hi-MO 7 620W is the stronger choice.
Key Differences
- • LONGi Hi-MO 7 590W is rated at 590W while LONGi Hi-MO 7 620W is rated at 620W, a 30W difference.
- • LONGi Hi-MO 7 620W achieves 23% efficiency vs 22.8% for the other, a 0.2 percentage point gap.
- • Both carry matching 12-year product warranties.
Specifications Breakdown
Module Efficiency
The LONGi Hi-MO 7 620W achieves 23% module efficiency compared to LONGi Hi-MO 7 590W's 22.8%, meaning LONGi Hi-MO 7 620W converts 0.2 percentage points more sunlight into electricity per square meter. In practical terms, the LONGi Hi-MO 7 590W produces 228.4 watts per square meter of panel area while the LONGi Hi-MO 7 620W produces 229.3 W/m². For rooftop installations where space is limited, this efficiency gap determines how many kilowatts you can fit on your available roof area. Over a 25-year system life, even a small efficiency advantage compounds into meaningful additional energy production.
Power Output
The LONGi Hi-MO 7 620W delivers 620W per panel versus 590W for the LONGi Hi-MO 7 590W, a 30W difference per module. To build an 8 kW residential system, you would need 14 LONGi Hi-MO 7 590W panels or 13 LONGi Hi-MO 7 620W panels. Choosing the higher-wattage option saves 1 panel, reducing total racking hardware, wiring, and installation labor costs. Higher wattage per panel is particularly valuable for commercial-scale installations where panel count directly impacts balance-of-system costs.
Temperature Coefficient
Both panels share an identical temperature coefficient of -0.28%/°C, meaning they lose power at the same rate as cell temperature rises above the 25°C standard test baseline. At 65°C cell temperature, both retain 94.4% of rated power. Neither panel has a thermal performance advantage, which makes this specification a non-factor in the comparison.
Warranty Coverage
The LONGi Hi-MO 7 590W is backed by a 12-year product warranty and 30-year performance guarantee, while the LONGi Hi-MO 7 620W offers 12-year product and 30-year performance coverage. Both offer identical product warranty duration. Based on their published degradation rates (1% first year then 0.4%/year for LONGi Hi-MO 7 590W; 0.5% first year then 0.35%/year for LONGi Hi-MO 7 620W), after 25 years the LONGi Hi-MO 7 590W should retain approximately 89.4% of original output versus 91.1% for the LONGi Hi-MO 7 620W. This 1.7 percentage point gap in end-of-life output meaningfully impacts lifetime energy economics.
Physical Dimensions & Weight
The LONGi Hi-MO 7 590W measures 2278×1134×35mm and weighs 28.8 kg, while the LONGi Hi-MO 7 620W measures 2384×1134×35mm at 31 kg. 2.58 m² of panel area for the LONGi Hi-MO 7 590W versus 2.70 m² for the LONGi Hi-MO 7 620W. The LONGi Hi-MO 7 590W is 2.2 kg lighter per panel, which reduces structural load requirements on the roof and makes handling easier during installation. For a 20-panel system, that is a total weight difference of 44 kg. The more compact LONGi Hi-MO 7 590W may be easier to fit on irregularly shaped or space-limited rooftops.
Specification Comparison
| Specification | LONGi Hi-MO 7 590W | LONGi Hi-MO 7 620W |
|---|---|---|
| Power | 590W | 620W |
| Efficiency | 22.8% | 23% |
| Power Density | 21.2 W/sq ft | 21.3 W/sq ft |
| Cell Type | HPBC (Back Contact N-type) | HPBC (Back Contact N-type) |
| Bifacial | Yes | Yes |
| Weight | 28.8 kg | 31 kg |
| Temp Coefficient | -0.28%/°C | -0.28%/°C |
| Snow Load | 5400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 2400 Pa |
| Product Warranty | 12 years | 12 years |
| Performance Warranty | 30 years | 30 years |
| Degradation (Year 1) | 1% | 0.5% |
| Annual Degradation | 0.4% | 0.35% |
| Country | China | China |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: LONGi Hi-MO 7 620WThe LONGi Hi-MO 7 620W achieves 23% efficiency versus 22.8% — a 0.2 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 0.9 kW more total system capacity, or 5 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: TieBoth panels share a temperature coefficient of -0.28%/°C — identical heat tolerance.
3. Durability & Warranty
Winner: LONGi Hi-MO 7 620WLONGi Hi-MO 7 620W degrades more slowly at 0.35% per year versus 0.4%. After 25 years, expect 89.4% vs 91.1% of original output for LONGi Hi-MO 7 590W and LONGi Hi-MO 7 620W respectively.
4. Power Output
Winner: LONGi Hi-MO 7 620WThe LONGi Hi-MO 7 620W delivers 620W versus 590W per panel — 30W more. For an 8 kW system, you need 13 panels with the higher-wattage option versus 14 panels, saving 1 panels and the associated racking and labor costs.
5. Cell Technology
Winner: TieBoth panels use HPBC (Back Contact N-type) cell technology. No technology advantage for either product.
LONGi Hi-MO 7 590W
The Hi-MO 7 is LONGi's flagship residential panel using proprietary HPBC (Hybrid Passivated Back Contact) cell technology for exceptional 22.8% efficiency and 590W output.
Pros
- + Industry-leading HPBC back-contact technology
- + 22.8% efficiency
- + Excellent temperature coefficient
- + Lower degradation rate
Cons
- - Premium pricing
- - Heavy at 28.8 kg
- - New technology with limited track record
LONGi Hi-MO 7 620W
The Hi-MO 7 620W is LONGi's highest-output panel using proprietary HPBC (Hybrid Passivated Back Contact) technology for exceptional efficiency. Newer LR7/LR8 variants support 620W+ output.
Pros
- + Highest LONGi output
- + HPBC cutting-edge back-contact technology
- + 23.0% efficiency
- + Excellent degradation profile
Cons
- - Very large form factor
- - Premium pricing
- - New technology
Choose LONGi Hi-MO 7 590W If...
- ✓ Premium residential installations seeking maximum efficiency.
Choose LONGi Hi-MO 7 620W If...
- ✓ Your roof space is limited and you need maximum power per panel
- ✓ You want fewer panels to reach your target system size, reducing racking and labor costs
- ✓ You want maximum output retention over the system's 25-30 year lifespan
- ✓ Large installations wanting LONGi's most advanced HPBC technology.
Our Recommendation
Both the LONGi Hi-MO 7 590W and LONGi Hi-MO 7 620W are excellent solar panel options, and the margin between them is narrow. The LONGi Hi-MO 7 620W wins 3 of 5 comparison dimensions by a slim margin. Your decision may come down to local pricing, installer availability, and which specific performance metrics matter most for your project. Either product is a solid investment.
Frequently Asked Questions
Which is better, LONGi Hi-MO 7 590W or LONGi Hi-MO 7 620W?
The LONGi Hi-MO 7 620W wins this comparison by a narrow margin. It leads in efficiency (23% vs 22.8%) and matches or exceeds on warranty (12 vs 12 years). For most residential installations, the LONGi Hi-MO 7 620W is the stronger choice.
Which panel is more efficient, LONGi Hi-MO 7 590W or LONGi Hi-MO 7 620W?
The LONGi Hi-MO 7 620W at 23% module efficiency. Higher efficiency means more watts per square foot of roof space, which is critical for space-constrained installations. The difference of 0.2 percentage points translates to approximately 30W per panel under standard test conditions.
Which has a better warranty, LONGi Hi-MO 7 590W or LONGi Hi-MO 7 620W?
The LONGi Hi-MO 7 590W comes with a 12-year product warranty and 30-year performance guarantee. The LONGi Hi-MO 7 620W offers 12-year product and 30-year performance warranties. Both offer identical warranty terms.
Which panel performs better in hot weather?
The LONGi Hi-MO 7 590W has a temperature coefficient of -0.28%/°C and the LONGi Hi-MO 7 620W is -0.28%/°C. Both handle heat equally. A lower (less negative) temperature coefficient is better.
How many LONGi Hi-MO 7 590W vs LONGi Hi-MO 7 620W panels do I need for an 8 kW system?
For an 8 kW system: you need 14 LONGi Hi-MO 7 590W panels (590W each) or 13 LONGi Hi-MO 7 620W panels (620W each). The LONGi Hi-MO 7 620W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026