First Solar Series 7 545W vs Tongwei THN-EP08M10 580W
The Tongwei THN-EP08M10 580W wins this comparison by a decisive margin. It leads in efficiency (22.5% vs 19.8%) and matches or exceeds on warranty (12 vs 10 years). For most residential installations, the Tongwei THN-EP08M10 580W is the stronger choice.
Key Differences
- • First Solar Series 7 545W is rated at 545W while Tongwei THN-EP08M10 580W is rated at 580W, a 35W difference.
- • Tongwei THN-EP08M10 580W achieves 22.5% efficiency vs 19.8% for the other, a 2.7 percentage point gap.
- • Tongwei THN-EP08M10 580W comes with a 12-year product warranty vs 10 years for the other.
- • First Solar Series 7 545W has a superior temperature coefficient of -0.28%/°C vs -0.29%/°C, retaining more power in hot climates.
- • First Solar Series 7 545W uses CdTe (Cadmium Telluride) cells while Tongwei THN-EP08M10 580W uses TOPCon N-type cells, representing different technology generations.
Specifications Breakdown
Module Efficiency
The Tongwei THN-EP08M10 580W achieves 22.5% module efficiency compared to First Solar Series 7 545W's 19.8%, meaning Tongwei THN-EP08M10 580W converts 2.7 percentage points more sunlight into electricity per square meter. In practical terms, the First Solar Series 7 545W produces 173.9 watts per square meter of panel area while the Tongwei THN-EP08M10 580W produces 224.5 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 Tongwei THN-EP08M10 580W delivers 580W per panel versus 545W for the First Solar Series 7 545W, a 35W difference per module. To build an 8 kW residential system, you would need 15 First Solar Series 7 545W panels or 14 Tongwei THN-EP08M10 580W 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
The First Solar Series 7 545W has a temperature coefficient of -0.28%/°C versus -0.29%/°C for the Tongwei THN-EP08M10 580W. On a hot summer day when cell temperature reaches 65°C (40°C above the 25°C STC baseline), the First Solar Series 7 545W 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 First Solar Series 7 545W is backed by a 10-year product warranty and 30-year performance guarantee, while the Tongwei THN-EP08M10 580W offers 12-year product and 25-year performance coverage. The Tongwei THN-EP08M10 580W provides 2 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 First Solar Series 7 545W; 1% first year then 0.4%/year for Tongwei THN-EP08M10 580W), after 25 years the First Solar Series 7 545W should retain approximately 86.5% of original output versus 89.4% for the Tongwei THN-EP08M10 580W. This 2.9 percentage point gap in end-of-life output meaningfully impacts lifetime energy economics.
Physical Dimensions & Weight
The First Solar Series 7 545W measures 2520×1244×49mm and weighs 38 kg, while the Tongwei THN-EP08M10 580W measures 2278×1134×35mm at 28.5 kg. 3.13 m² of panel area for the First Solar Series 7 545W versus 2.58 m² for the Tongwei THN-EP08M10 580W. The Tongwei THN-EP08M10 580W 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 Tongwei THN-EP08M10 580W may be easier to fit on irregularly shaped or space-limited rooftops.
Specification Comparison
| Specification | First Solar Series 7 545W | Tongwei THN-EP08M10 580W |
|---|---|---|
| Power | 545W | 580W |
| Efficiency | 19.8% | 22.5% |
| Power Density | 16.2 W/sq ft | 20.9 W/sq ft |
| Cell Type | CdTe (Cadmium Telluride) | TOPCon N-type |
| Bifacial | No | No |
| Weight | 38 kg | 28.5 kg |
| Temp Coefficient | -0.28%/°C | -0.29%/°C |
| Snow Load | 5400 Pa | 5400 Pa |
| Wind Load | 4000 Pa | 2400 Pa |
| Product Warranty | 10 years | 12 years |
| Performance Warranty | 30 years | 25 years |
| Degradation (Year 1) | 1.5% | 1% |
| Annual Degradation | 0.5% | 0.4% |
| Country | United States | China |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: Tongwei THN-EP08M10 580WThe Tongwei THN-EP08M10 580W achieves 22.5% efficiency versus 19.8% — a 2.7 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 1.1 kW more total system capacity, or 5 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: First Solar Series 7 545WThe First Solar Series 7 545W 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: Tongwei THN-EP08M10 580WTongwei THN-EP08M10 580W leads with a 12-year product warranty versus 10 years. Tongwei THN-EP08M10 580W degrades more slowly at 0.4% per year versus 0.5%. After 25 years, expect 86.5% vs 89.4% of original output for First Solar Series 7 545W and Tongwei THN-EP08M10 580W respectively.
4. Power Output
Winner: Tongwei THN-EP08M10 580WThe Tongwei THN-EP08M10 580W delivers 580W versus 545W per panel — 35W more. For an 8 kW system, you need 14 panels with the higher-wattage option versus 15 panels, saving 1 panels and the associated racking and labor costs.
5. Cell Technology
Winner: Tongwei THN-EP08M10 580WThe First Solar Series 7 545W uses CdTe (Cadmium Telluride): CdTe (Cadmium Telluride). The Tongwei THN-EP08M10 580W 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.
First Solar Series 7 545W
First Solar Series 7 is a US-made thin-film CdTe module delivering 545W with superior temperature performance and sustainable manufacturing.
Pros
- + US manufactured thin-film
- + Excellent hot weather performance
- + Lower carbon footprint
- + No supply chain issues
Cons
- - Lower efficiency than crystalline silicon
- - Very large and heavy
- - Not for residential roofs
Tongwei THN-EP08M10 580W
Tongwei THN-EP08M10 is a high-output N-type TOPCon panel from one of the world's largest solar cell manufacturers.
Pros
- + Top cell manufacturer
- + High 580W output
- + Competitive pricing
- + Strong R&D backing
Cons
- - Limited brand recognition outside China
- - Standard warranty
- - Newer to module market
Choose First Solar Series 7 545W If...
- ✓ You live in a hot climate (Arizona, Texas, Florida) where heat performance matters
- ✓ Utility-scale projects valuing US manufacturing and hot-climate performance.
Choose Tongwei THN-EP08M10 580W 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 12+ years
- ✓ You want maximum output retention over the system's 25-30 year lifespan
- ✓ You prefer newer cell technology with a longer performance improvement runway
Our Recommendation
The Tongwei THN-EP08M10 580W is the decisive winner in this solar panel comparison, outperforming the First Solar Series 7 545W in 4 of 5 dimensions. Unless you have a specific requirement that the First Solar Series 7 545W uniquely addresses, the Tongwei THN-EP08M10 580W is the stronger choice for virtually every installation scenario.
Frequently Asked Questions
Which is better, First Solar Series 7 545W or Tongwei THN-EP08M10 580W?
The Tongwei THN-EP08M10 580W wins this comparison by a decisive margin. It leads in efficiency (22.5% vs 19.8%) and matches or exceeds on warranty (12 vs 10 years). For most residential installations, the Tongwei THN-EP08M10 580W is the stronger choice.
Which panel is more efficient, First Solar Series 7 545W or Tongwei THN-EP08M10 580W?
The Tongwei THN-EP08M10 580W at 22.5% module efficiency. Higher efficiency means more watts per square foot of roof space, which is critical for space-constrained installations. The difference of 2.7 percentage points translates to approximately 35W per panel under standard test conditions.
Which has a better warranty, First Solar Series 7 545W or Tongwei THN-EP08M10 580W?
The First Solar Series 7 545W comes with a 10-year product warranty and 30-year performance guarantee. The Tongwei THN-EP08M10 580W offers 12-year product and 25-year performance warranties. Tongwei THN-EP08M10 580W provides 2 additional years of product coverage.
Which panel performs better in hot weather?
The First Solar Series 7 545W has a temperature coefficient of -0.28%/°C and the Tongwei THN-EP08M10 580W is -0.29%/°C. First Solar Series 7 545W retains more power in heat — important in states like Arizona, Texas, and Florida. A lower (less negative) temperature coefficient is better.
How many First Solar Series 7 545W vs Tongwei THN-EP08M10 580W panels do I need for an 8 kW system?
For an 8 kW system: you need 15 First Solar Series 7 545W panels (545W each) or 14 Tongwei THN-EP08M10 580W panels (580W each). The Tongwei THN-EP08M10 580W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026