Trina Solar Vertex S+ 445W vs JA Solar JAM78S30 590W
The JA Solar JAM78S30 590W wins this comparison by a clear margin. It leads in efficiency (22.6% vs 22.3%) and matches or exceeds on warranty (15 vs 15 years). For most residential installations, the JA Solar JAM78S30 590W is the stronger choice.
Key Differences
- • Trina Solar Vertex S+ 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 22.3% for the other, a 0.3 percentage point gap.
- • Both carry matching 15-year product warranties.
- • 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 Trina Solar Vertex S+ 445W's 22.3%, meaning JA Solar JAM78S30 590W converts 0.3 percentage points more sunlight into electricity per square meter. In practical terms, the Trina Solar Vertex S+ 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 Trina Solar Vertex S+ 445W, a 145W difference per module. To build an 8 kW residential system, you would need 18 Trina Solar Vertex S+ 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 Trina Solar Vertex S+ 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 Trina Solar Vertex S+ 445W is backed by a 15-year product warranty and 30-year performance guarantee, while the JA Solar JAM78S30 590W offers 15-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 Trina Solar Vertex S+ 445W; 1% first year then 0.4%/year for JA Solar JAM78S30 590W), after 25 years the Trina Solar Vertex S+ 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 Trina Solar Vertex S+ 445W measures 1722×1134×30mm and weighs 21.3 kg, while the JA Solar JAM78S30 590W measures 2384×1134×35mm at 31 kg. 1.95 m² of panel area for the Trina Solar Vertex S+ 445W versus 2.70 m² for the JA Solar JAM78S30 590W. The Trina Solar Vertex S+ 445W is 9.7 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 194 kg. The more compact Trina Solar Vertex S+ 445W may be easier to fit on irregularly shaped or space-limited rooftops.
Specification Comparison
| Specification | Trina Solar Vertex S+ 445W | JA Solar JAM78S30 590W |
|---|---|---|
| Power | 445W | 590W |
| Efficiency | 22.3% | 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 | 21.3 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 | 15 years | 15 years |
| Performance Warranty | 30 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 22.3% — a 0.3 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: TieBoth panels offer identical 15-year product warranties and 0.4% annual degradation. Neither has a durability advantage.
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.
Trina Solar Vertex S+ 445W
The Trina Vertex S+ delivers 445W using N-type TOPCon technology in a compact residential format with excellent all-round performance.
Pros
- + Compact residential size
- + Strong N-type efficiency
- + Good shade tolerance
- + 30-year performance warranty
Cons
- - Moderate weight
- - Not the highest wattage option
- - Limited color options
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 Trina Solar Vertex S+ 445W If...
- ✓ You prefer newer cell technology with a longer performance improvement runway
- ✓ Residential rooftops with moderate space requiring high efficiency.
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
- ✓ You live in a hot climate (Arizona, Texas, Florida) where heat performance matters
- ✓ You prefer newer cell technology with a longer performance improvement runway
- ✓ Large commercial or ground-mount systems requiring maximum output.
Our Recommendation
We recommend the JA Solar JAM78S30 590W for most buyers in this comparison. It wins 3 of 5 key dimensions and offers a clear advantage in the metrics that matter most for a solar panel purchase. The Trina Solar Vertex S+ 445W remains a good product, but the JA Solar JAM78S30 590W delivers better overall value for the majority of installations.
Frequently Asked Questions
Which is better, Trina Solar Vertex S+ 445W or JA Solar JAM78S30 590W?
The JA Solar JAM78S30 590W wins this comparison by a clear margin. It leads in efficiency (22.6% vs 22.3%) and matches or exceeds on warranty (15 vs 15 years). For most residential installations, the JA Solar JAM78S30 590W is the stronger choice.
Which panel is more efficient, Trina Solar Vertex S+ 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 0.3 percentage points translates to approximately 145W per panel under standard test conditions.
Which has a better warranty, Trina Solar Vertex S+ 445W or JA Solar JAM78S30 590W?
The Trina Solar Vertex S+ 445W comes with a 15-year product warranty and 30-year performance guarantee. The JA Solar JAM78S30 590W offers 15-year product and 30-year performance warranties. Both offer identical warranty terms.
Which panel performs better in hot weather?
The Trina Solar Vertex S+ 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 Trina Solar Vertex S+ 445W vs JA Solar JAM78S30 590W panels do I need for an 8 kW system?
For an 8 kW system: you need 18 Trina Solar Vertex S+ 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