LONGi Hi-MO 6 580W vs JA Solar JAM78S30 590W
The JA Solar JAM78S30 590W wins this comparison by a decisive margin. It leads in efficiency (22.6% vs 22.3%) 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 6 580W is rated at 580W while JA Solar JAM78S30 590W is rated at 590W, a 10W difference.
- • JA Solar JAM78S30 590W achieves 22.6% efficiency vs 22.3% for the other, a 0.3 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 -0.34%/°C, retaining more power in hot climates.
- • LONGi Hi-MO 6 580W uses PERC Mono Half-cut cells while JA Solar JAM78S30 590W uses TOPCon N-type cells, representing different technology generations.
Specifications Breakdown
Module Efficiency
The JA Solar JAM78S30 590W achieves 22.6% module efficiency compared to LONGi Hi-MO 6 580W's 22.3%, meaning JA Solar JAM78S30 590W converts 0.3 percentage points more sunlight into electricity per square meter. In practical terms, the LONGi Hi-MO 6 580W produces 224.5 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 580W for the LONGi Hi-MO 6 580W, a 10W difference per module. To build an 8 kW residential system, you would need 14 LONGi Hi-MO 6 580W panels or 14 JA Solar JAM78S30 590W panels. Despite the per-panel wattage difference, both require the same number of panels for this system size due to rounding. 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 -0.34%/°C for the LONGi Hi-MO 6 580W. 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 93.2%. This difference is particularly significant in hot climates such as the American Southwest, the Middle East, and Southeast Asia, where panels routinely operate 30-40°C above STC for several hours each day. Over the system lifetime, the cumulative energy advantage from a better temperature coefficient can amount to 2-4% of total production.
Warranty Coverage
The LONGi Hi-MO 6 580W 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 (1.5% first year then 0.5%/year for LONGi Hi-MO 6 580W; 1% first year then 0.4%/year for JA Solar JAM78S30 590W), after 25 years the LONGi Hi-MO 6 580W should retain approximately 86.5% of original output versus 89.4% for the JA Solar JAM78S30 590W. This 2.9 percentage point gap in end-of-life output meaningfully impacts lifetime energy economics.
Physical Dimensions & Weight
The LONGi Hi-MO 6 580W measures 2278×1134×35mm and weighs 28.4 kg, while the JA Solar JAM78S30 590W measures 2384×1134×35mm at 31 kg. 2.58 m² of panel area for the LONGi Hi-MO 6 580W versus 2.70 m² for the JA Solar JAM78S30 590W. The LONGi Hi-MO 6 580W is 2.6 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 52 kg. The more compact LONGi Hi-MO 6 580W may be easier to fit on irregularly shaped or space-limited rooftops.
Specification Comparison
| Specification | LONGi Hi-MO 6 580W | JA Solar JAM78S30 590W |
|---|---|---|
| Power | 580W | 590W |
| Efficiency | 22.3% | 22.6% |
| Power Density | 20.9 W/sq ft | 20.3 W/sq ft |
| Cell Type | PERC Mono Half-cut | TOPCon N-type |
| Bifacial | No | No |
| Weight | 28.4 kg | 31 kg |
| Temp Coefficient | -0.34%/°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) | 1.5% | 1% |
| Annual Degradation | 0.5% | 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 22.3% — a 0.3 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 0.3 kW more total system capacity, or 2 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 -0.34%/°C. On a 45°C summer day (20°C above STC), the winner retains 94.4% of rated power versus 93.2%. This is a meaningful difference in hot states like Arizona, Texas, and Florida.
3. Durability & Warranty
Winner: JA Solar JAM78S30 590WJA Solar JAM78S30 590W leads with a 15-year product warranty versus 12 years. JA Solar JAM78S30 590W degrades more slowly at 0.4% per year versus 0.5%. After 25 years, expect 86.5% vs 89.4% of original output for LONGi Hi-MO 6 580W and JA Solar JAM78S30 590W respectively.
4. Power Output
Winner: JA Solar JAM78S30 590WThe JA Solar JAM78S30 590W delivers 590W versus 580W per panel — 10W more. For an 8 kW system, you need 14 panels with the higher-wattage option versus 14 panels, saving 0 panels and the associated racking and labor costs.
5. Cell Technology
Winner: JA Solar JAM78S30 590WThe LONGi Hi-MO 6 580W uses PERC Mono Half-cut: PERC (Passivated Emitter Rear Cell) is the current mainstream technology, offering good efficiency at the lowest manufacturing cost. The JA Solar JAM78S30 590W uses TOPCon N-type: TOPCon (Tunnel Oxide Passivated Contact) adds a thin tunnel oxide layer to reduce recombination losses, achieving higher efficiency than PERC while being manufacturable on existing production lines. TOPCon N-type represents a newer generation technology with a longer performance runway as manufacturing matures.
LONGi Hi-MO 6 580W
LONGi Hi-MO 6 is a high-performance PERC mono half-cut panel delivering 580W with 22.3% efficiency, ideal for residential and commercial rooftops.
Pros
- + High 22.3% efficiency
- + Proven PERC technology
- + Strong bifacial gain potential
- + Competitive pricing
Cons
- - Large physical size
- - Requires compatible racking
- - Limited US availability
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 6 580W If...
- ✓ Homeowners wanting high-output PERC performance at a competitive price.
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 want maximum output retention over the system's 25-30 year lifespan
Our Recommendation
The JA Solar JAM78S30 590W is the decisive winner in this solar panel comparison, outperforming the LONGi Hi-MO 6 580W in 5 of 5 dimensions. Unless you have a specific requirement that the LONGi Hi-MO 6 580W 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 6 580W or JA Solar JAM78S30 590W?
The JA Solar JAM78S30 590W wins this comparison by a decisive margin. It leads in efficiency (22.6% vs 22.3%) 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 6 580W 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 0.3 percentage points translates to approximately 10W per panel under standard test conditions.
Which has a better warranty, LONGi Hi-MO 6 580W or JA Solar JAM78S30 590W?
The LONGi Hi-MO 6 580W 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 6 580W has a temperature coefficient of -0.34%/°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 6 580W vs JA Solar JAM78S30 590W panels do I need for an 8 kW system?
For an 8 kW system: you need 14 LONGi Hi-MO 6 580W panels (580W 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