LONGi Hi-MO X6 445W vs JA Solar JAM78S30 590W
The JA Solar JAM78S30 590W wins this comparison by a decisive margin. It leads in efficiency (22.6% vs 22%) and matches or exceeds on warranty (15 vs 12 years). For most residential installations, the JA Solar JAM78S30 590W is the stronger choice.
Key Differences
- • LONGi Hi-MO X6 445W is rated at 445W while JA Solar JAM78S30 590W is rated at 590W, a 145W difference.
- • JA Solar JAM78S30 590W achieves 22.6% efficiency vs 22% for the other, a 0.6 percentage point gap.
- • JA Solar JAM78S30 590W comes with a 15-year product warranty vs 12 years for the other.
- • JA Solar JAM78S30 590W has a superior temperature coefficient of -0.28%/°C vs -0.29%/°C, retaining more power in hot climates.
Specifications Breakdown
Module Efficiency
The JA Solar JAM78S30 590W achieves 22.6% module efficiency compared to LONGi Hi-MO X6 445W's 22%, meaning JA Solar JAM78S30 590W converts 0.6 percentage points more sunlight into electricity per square meter. In practical terms, the LONGi Hi-MO X6 445W produces 227.9 watts per square meter of panel area while the JA Solar JAM78S30 590W produces 218.2 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 JA Solar JAM78S30 590W delivers 590W per panel versus 445W for the LONGi Hi-MO X6 445W, a 145W difference per module. To build an 8 kW residential system, you would need 18 LONGi Hi-MO X6 445W panels or 14 JA Solar JAM78S30 590W panels. Choosing the higher-wattage option saves 4 panels, 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
The JA Solar JAM78S30 590W has a temperature coefficient of -0.28%/°C versus -0.29%/°C for the LONGi Hi-MO X6 445W. On a hot summer day when cell temperature reaches 65°C (40°C above the 25°C STC baseline), the JA Solar JAM78S30 590W retains 94.4% of its rated power while the other retains 94.2%. While the numerical gap is modest, it still accumulates over decades of summer production, especially in southern latitudes with prolonged peak heat hours.
Warranty Coverage
The LONGi Hi-MO X6 445W is backed by a 12-year product warranty and 25-year performance guarantee, while the JA Solar JAM78S30 590W offers 15-year product and 30-year performance coverage. The JA Solar JAM78S30 590W provides 3 additional years of defect protection, covering manufacturing issues, material failures, and premature performance loss. Based on their published degradation rates (1% first year then 0.4%/year for LONGi Hi-MO X6 445W; 1% first year then 0.4%/year for JA Solar JAM78S30 590W), after 25 years the LONGi Hi-MO X6 445W should retain approximately 89.4% of original output versus 89.4% for the JA Solar JAM78S30 590W. The end-of-life output levels are closely matched.
Physical Dimensions & Weight
The LONGi Hi-MO X6 445W measures 1722×1134×30mm and weighs 21.5 kg, while the JA Solar JAM78S30 590W measures 2384×1134×35mm at 31 kg. 1.95 m² of panel area for the LONGi Hi-MO X6 445W versus 2.70 m² for the JA Solar JAM78S30 590W. The LONGi Hi-MO X6 445W is 9.5 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 190 kg. The more compact LONGi Hi-MO X6 445W may be easier to fit on irregularly shaped or space-limited rooftops.
Specification Comparison
| Specification | LONGi Hi-MO X6 445W | JA Solar JAM78S30 590W |
|---|---|---|
| Power | 445W | 590W |
| Efficiency | 22% | 22.6% |
| Power Density | 21.2 W/sq ft | 20.3 W/sq ft |
| Cell Type | TOPCon N-type | TOPCon N-type |
| Bifacial | Yes | No |
| Weight | 21.5 kg | 31 kg |
| Temp Coefficient | -0.29%/°C | -0.28%/°C |
| Snow Load | 5400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 2400 Pa |
| Product Warranty | 12 years | 15 years |
| Performance Warranty | 25 years | 30 years |
| Degradation (Year 1) | 1% | 1% |
| Annual Degradation | 0.4% | 0.4% |
| Country | China | China |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: JA Solar JAM78S30 590WThe JA Solar JAM78S30 590W achieves 22.6% efficiency versus 22% — a 0.6 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 4.3 kW more total system capacity, or 20 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: JA Solar JAM78S30 590WThe JA Solar JAM78S30 590W has a better temperature coefficient of -0.28%/°C versus -0.29%/°C. On a 45°C summer day (20°C above STC), the winner retains 94.4% of rated power versus 94.2%. The difference is modest but accumulates over 25 years of summer production.
3. Durability & Warranty
Winner: JA Solar JAM78S30 590WJA Solar JAM78S30 590W leads with a 15-year product warranty versus 12 years. After 25 years, expect 89.4% vs 89.4% of original output for LONGi Hi-MO X6 445W and JA Solar JAM78S30 590W respectively.
4. Power Output
Winner: JA Solar JAM78S30 590WThe JA Solar JAM78S30 590W delivers 590W versus 445W per panel — 145W more. For an 8 kW system, you need 14 panels with the higher-wattage option versus 18 panels, saving 4 panels and the associated racking and labor costs.
5. Cell Technology
Winner: TieBoth panels use TOPCon N-type cell technology. No technology advantage for either product.
LONGi Hi-MO X6 445W
The Hi-MO X6 is LONGi's TOPCon N-type line offering 445W in a compact format, well-suited for space-constrained residential rooftops.
Pros
- + Compact size for residential roofs
- + Good N-type TOPCon efficiency
- + Advanced technology
- + Budget-friendly
Cons
- - Lower wattage than larger models
- - Mid-range efficiency for N-type
- - Less suited for very large roofs
JA Solar JAM78S30 590W
JA Solar's JAM78S30 is a high-wattage N-type TOPCon module achieving 22.6% efficiency for large-scale installations.
Pros
- + Very high 590W output
- + Excellent efficiency
- + Low temperature coefficient
- + Bifacial design
Cons
- - Very large and heavy
- - Requires heavy-duty mounting
- - Not for small roofs
Choose LONGi Hi-MO X6 445W If...
- ✓ You prefer newer cell technology with a longer performance improvement runway
- ✓ Homeowners wanting N-type TOPCon technology in a compact residential format.
Choose JA Solar JAM78S30 590W 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
- ✓ Long-term warranty protection is a top priority and you plan to stay in your home for 15+ years
- ✓ You live in a hot climate (Arizona, Texas, Florida) where heat performance matters
- ✓ You prefer newer cell technology with a longer performance improvement runway
Our Recommendation
The JA Solar JAM78S30 590W is the decisive winner in this solar panel comparison, outperforming the LONGi Hi-MO X6 445W in 4 of 5 dimensions. Unless you have a specific requirement that the LONGi Hi-MO X6 445W uniquely addresses, the JA Solar JAM78S30 590W is the stronger choice for virtually every installation scenario.
Frequently Asked Questions
Which is better, LONGi Hi-MO X6 445W or JA Solar JAM78S30 590W?
The JA Solar JAM78S30 590W wins this comparison by a decisive margin. It leads in efficiency (22.6% vs 22%) and matches or exceeds on warranty (15 vs 12 years). For most residential installations, the JA Solar JAM78S30 590W is the stronger choice.
Which panel is more efficient, LONGi Hi-MO X6 445W or JA Solar JAM78S30 590W?
The JA Solar JAM78S30 590W at 22.6% module efficiency. Higher efficiency means more watts per square foot of roof space, which is critical for space-constrained installations. The difference of 0.6 percentage points translates to approximately 145W per panel under standard test conditions.
Which has a better warranty, LONGi Hi-MO X6 445W or JA Solar JAM78S30 590W?
The LONGi Hi-MO X6 445W comes with a 12-year product warranty and 25-year performance guarantee. The JA Solar JAM78S30 590W offers 15-year product and 30-year performance warranties. JA Solar JAM78S30 590W provides 3 additional years of product coverage.
Which panel performs better in hot weather?
The LONGi Hi-MO X6 445W has a temperature coefficient of -0.29%/°C and the JA Solar JAM78S30 590W is -0.28%/°C. JA Solar JAM78S30 590W retains more power in heat — important in states like Arizona, Texas, and Florida. A lower (less negative) temperature coefficient is better.
How many LONGi Hi-MO X6 445W vs JA Solar JAM78S30 590W panels do I need for an 8 kW system?
For an 8 kW system: you need 18 LONGi Hi-MO X6 445W panels (445W each) or 14 JA Solar JAM78S30 590W panels (590W each). The JA Solar JAM78S30 590W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026