JA Solar JAM54S31 415W vs Panasonic EVPV400H
The Panasonic EVPV400H wins this comparison by a decisive margin. It offers better long-term durability with 25-year warranty. For most residential installations, the Panasonic EVPV400H is the stronger choice.
Key Differences
- • JA Solar JAM54S31 415W is rated at 415W while Panasonic EVPV400H is rated at 400W, a 15W difference.
- • JA Solar JAM54S31 415W achieves 21.5% efficiency vs 21.2% for the other, a 0.3 percentage point gap.
- • Panasonic EVPV400H comes with a 25-year product warranty vs 12 years for the other.
- • Panasonic EVPV400H has a superior temperature coefficient of -0.26%/°C vs -0.34%/°C, retaining more power in hot climates.
- • JA Solar JAM54S31 415W uses PERC Mono cells while Panasonic EVPV400H uses HJT (Heterojunction) cells, representing different technology generations.
Specifications Breakdown
Module Efficiency
The JA Solar JAM54S31 415W achieves 21.5% module efficiency compared to Panasonic EVPV400H's 21.2%, meaning JA Solar JAM54S31 415W converts 0.3 percentage points more sunlight into electricity per square meter. In practical terms, the JA Solar JAM54S31 415W produces 212.5 watts per square meter of panel area while the Panasonic EVPV400H produces 204.8 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 JAM54S31 415W delivers 415W per panel versus 400W for the Panasonic EVPV400H, a 15W difference per module. To build an 8 kW residential system, you would need 20 JA Solar JAM54S31 415W panels or 20 Panasonic EVPV400H 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 Panasonic EVPV400H has a temperature coefficient of -0.26%/°C versus -0.34%/°C for the JA Solar JAM54S31 415W. On a hot summer day when cell temperature reaches 65°C (40°C above the 25°C STC baseline), the Panasonic EVPV400H retains 94.8% 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 JA Solar JAM54S31 415W is backed by a 12-year product warranty and 25-year performance guarantee, while the Panasonic EVPV400H offers 25-year product and 25-year performance coverage. The Panasonic EVPV400H provides 13 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 JA Solar JAM54S31 415W; 0.5% first year then 0.35%/year for Panasonic EVPV400H), after 25 years the JA Solar JAM54S31 415W should retain approximately 86.5% of original output versus 91.1% for the Panasonic EVPV400H. This 4.6 percentage point gap in end-of-life output meaningfully impacts lifetime energy economics.
Physical Dimensions & Weight
The JA Solar JAM54S31 415W measures 1722×1134×30mm and weighs 21.5 kg, while the Panasonic EVPV400H measures 1722×1134×30mm at 21 kg. 1.95 m² of panel area for the JA Solar JAM54S31 415W versus 1.95 m² for the Panasonic EVPV400H. Their weights are closely matched, so neither panel imposes a significantly different structural load on the mounting system. Similar footprints mean both panels fit comparably on standard residential rooftop configurations.
Specification Comparison
| Specification | JA Solar JAM54S31 415W | Panasonic EVPV400H |
|---|---|---|
| Power | 415W | 400W |
| Efficiency | 21.5% | 21.2% |
| Power Density | 19.7 W/sq ft | 19.0 W/sq ft |
| Cell Type | PERC Mono | HJT (Heterojunction) |
| Bifacial | No | Yes |
| Weight | 21.5 kg | 21 kg |
| Temp Coefficient | -0.34%/°C | -0.26%/°C |
| Snow Load | 5400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 2400 Pa |
| Product Warranty | 12 years | 25 years |
| Performance Warranty | 25 years | 25 years |
| Degradation (Year 1) | 1.5% | 0.5% |
| Annual Degradation | 0.5% | 0.35% |
| Country | China | Japan |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: JA Solar JAM54S31 415WThe JA Solar JAM54S31 415W achieves 21.5% efficiency versus 21.2% — a 0.3 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 0.5 kW more total system capacity, or 3 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: Panasonic EVPV400HThe Panasonic EVPV400H has a better temperature coefficient of -0.26%/°C versus -0.34%/°C. On a 45°C summer day (20°C above STC), the winner retains 94.8% of rated power versus 93.2%. This is a meaningful difference in hot states like Arizona, Texas, and Florida.
3. Durability & Warranty
Winner: Panasonic EVPV400HPanasonic EVPV400H leads with a 25-year product warranty versus 12 years. Panasonic EVPV400H degrades more slowly at 0.35% per year versus 0.5%. After 25 years, expect 86.5% vs 91.1% of original output for JA Solar JAM54S31 415W and Panasonic EVPV400H respectively.
4. Power Output
Winner: JA Solar JAM54S31 415WThe JA Solar JAM54S31 415W delivers 415W versus 400W per panel — 15W more. For an 8 kW system, you need 20 panels with the higher-wattage option versus 20 panels, saving 0 panels and the associated racking and labor costs.
5. Cell Technology
Winner: Panasonic EVPV400HThe JA Solar JAM54S31 415W uses PERC Mono: PERC (Passivated Emitter Rear Cell) is the current mainstream technology, offering good efficiency at the lowest manufacturing cost. The Panasonic EVPV400H uses HJT (Heterojunction): HJT (Heterojunction) combines crystalline silicon with amorphous silicon layers, delivering the best temperature coefficient and bifacial gains, but at higher manufacturing cost. HJT (Heterojunction) represents a newer generation technology with a longer performance runway as manufacturing matures.
JA Solar JAM54S31 415W
The JAM54S31 is a compact residential PERC panel delivering 415W with a solid balance of performance and affordability.
Pros
- + Compact residential form factor
- + Good price-performance ratio
- + Widely available
- + Proven reliability
Cons
- - Lower efficiency vs N-type
- - Higher degradation rate
- - Standard warranty
Panasonic EVPV400H
DISCONTINUED: Panasonic exited solar manufacturing in 2023. The EVPV400H was Panasonic's standard HJT residential panel, delivering 400W with the brand's signature quality and longevity.
Pros
- + Panasonic reliability
- + HJT advantages
- + Solid 25-year warranty
- + Good all-round performer
Cons
- - DISCONTINUED - no longer manufactured
- - No new units available
- - No ongoing product support
Choose JA Solar JAM54S31 415W 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
- ✓ Budget residential installations seeking reliable PERC performance.
Choose Panasonic EVPV400H If...
- ✓ Long-term warranty protection is a top priority and you plan to stay in your home for 25+ 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
- ✓ You prefer newer cell technology with a longer performance improvement runway
- ✓ No longer available for new installations.
Our Recommendation
The Panasonic EVPV400H is the decisive winner in this solar panel comparison, outperforming the JA Solar JAM54S31 415W in 3 of 5 dimensions. Unless you have a specific requirement that the JA Solar JAM54S31 415W uniquely addresses, the Panasonic EVPV400H is the stronger choice for virtually every installation scenario.
Frequently Asked Questions
Which is better, JA Solar JAM54S31 415W or Panasonic EVPV400H?
The Panasonic EVPV400H wins this comparison by a decisive margin. It offers better long-term durability with 25-year warranty. For most residential installations, the Panasonic EVPV400H is the stronger choice.
Which panel is more efficient, JA Solar JAM54S31 415W or Panasonic EVPV400H?
The JA Solar JAM54S31 415W at 21.5% 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 15W per panel under standard test conditions.
Which has a better warranty, JA Solar JAM54S31 415W or Panasonic EVPV400H?
The JA Solar JAM54S31 415W comes with a 12-year product warranty and 25-year performance guarantee. The Panasonic EVPV400H offers 25-year product and 25-year performance warranties. Panasonic EVPV400H provides 13 additional years of product coverage.
Which panel performs better in hot weather?
The JA Solar JAM54S31 415W has a temperature coefficient of -0.34%/°C and the Panasonic EVPV400H is -0.26%/°C. Panasonic EVPV400H retains more power in heat — important in states like Arizona, Texas, and Florida. A lower (less negative) temperature coefficient is better.
How many JA Solar JAM54S31 415W vs Panasonic EVPV400H panels do I need for an 8 kW system?
For an 8 kW system: you need 20 JA Solar JAM54S31 415W panels (415W each) or 20 Panasonic EVPV400H panels (400W each). The JA Solar JAM54S31 415W requires fewer panels, saving on racking hardware and installation labor.
Related Resources
Last updated: February 2026