Canadian Solar CS6R 420W vs Q CELLS Q.PEAK DUO BLK ML-G10+ 400W
The Q CELLS Q.PEAK DUO BLK ML-G10+ 400W wins this comparison by a decisive margin. It offers better long-term durability with 25-year warranty. For most residential installations, the Q CELLS Q.PEAK DUO BLK ML-G10+ 400W is the stronger choice.
Key Differences
- • Canadian Solar CS6R 420W is rated at 420W while Q CELLS Q.PEAK DUO BLK ML-G10+ 400W is rated at 400W, a 20W difference.
- • Canadian Solar CS6R 420W achieves 21% efficiency vs 20.9% for the other, a 0.1 percentage point gap.
- • Q CELLS Q.PEAK DUO BLK ML-G10+ 400W comes with a 25-year product warranty vs 12 years for the other.
Specifications Breakdown
Module Efficiency
The Canadian Solar CS6R 420W achieves 21% module efficiency compared to Q CELLS Q.PEAK DUO BLK ML-G10+ 400W's 20.9%, meaning Canadian Solar CS6R 420W converts 0.1 percentage points more sunlight into electricity per square meter. In practical terms, the Canadian Solar CS6R 420W produces 215.1 watts per square meter of panel area while the Q CELLS Q.PEAK DUO BLK ML-G10+ 400W 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 Canadian Solar CS6R 420W delivers 420W per panel versus 400W for the Q CELLS Q.PEAK DUO BLK ML-G10+ 400W, a 20W difference per module. To build an 8 kW residential system, you would need 20 Canadian Solar CS6R 420W panels or 20 Q CELLS Q.PEAK DUO BLK ML-G10+ 400W 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
Both panels share an identical temperature coefficient of -0.34%/°C, meaning they lose power at the same rate as cell temperature rises above the 25°C standard test baseline. At 65°C cell temperature, both retain 93.2% of rated power. Neither panel has a thermal performance advantage, which makes this specification a non-factor in the comparison.
Warranty Coverage
The Canadian Solar CS6R 420W is backed by a 12-year product warranty and 25-year performance guarantee, while the Q CELLS Q.PEAK DUO BLK ML-G10+ 400W offers 25-year product and 25-year performance coverage. The Q CELLS Q.PEAK DUO BLK ML-G10+ 400W 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 Canadian Solar CS6R 420W; 1% first year then 0.4%/year for Q CELLS Q.PEAK DUO BLK ML-G10+ 400W), after 25 years the Canadian Solar CS6R 420W should retain approximately 86.5% of original output versus 89.4% for the Q CELLS Q.PEAK DUO BLK ML-G10+ 400W. This 2.9 percentage point gap in end-of-life output meaningfully impacts lifetime energy economics.
Physical Dimensions & Weight
The Canadian Solar CS6R 420W measures 1722×1134×30mm and weighs 21 kg, while the Q CELLS Q.PEAK DUO BLK ML-G10+ 400W measures 1722×1134×30mm at 20.5 kg. 1.95 m² of panel area for the Canadian Solar CS6R 420W versus 1.95 m² for the Q CELLS Q.PEAK DUO BLK ML-G10+ 400W. 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 | Canadian Solar CS6R 420W | Q CELLS Q.PEAK DUO BLK ML-G10+ 400W |
|---|---|---|
| Power | 420W | 400W |
| Efficiency | 21% | 20.9% |
| Power Density | 20.0 W/sq ft | 19.0 W/sq ft |
| Cell Type | PERC Mono | PERC Mono |
| Bifacial | No | No |
| Weight | 21 kg | 20.5 kg |
| Temp Coefficient | -0.34%/°C | -0.34%/°C |
| Snow Load | 5400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 3600 Pa |
| Product Warranty | 12 years | 25 years |
| Performance Warranty | 25 years | 25 years |
| Degradation (Year 1) | 1.5% | 1% |
| Annual Degradation | 0.5% | 0.4% |
| Country | China | South Korea |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: Canadian Solar CS6R 420WThe Canadian Solar CS6R 420W achieves 21% efficiency versus 20.9% — a 0.1 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 0.6 kW more total system capacity, or 3 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: TieBoth panels share a temperature coefficient of -0.34%/°C — identical heat tolerance.
3. Durability & Warranty
Winner: Q CELLS Q.PEAK DUO BLK ML-G10+ 400WQ CELLS Q.PEAK DUO BLK ML-G10+ 400W leads with a 25-year product warranty versus 12 years. Q CELLS Q.PEAK DUO BLK ML-G10+ 400W degrades more slowly at 0.4% per year versus 0.5%. After 25 years, expect 86.5% vs 89.4% of original output for Canadian Solar CS6R 420W and Q CELLS Q.PEAK DUO BLK ML-G10+ 400W respectively.
4. Power Output
Winner: Canadian Solar CS6R 420WThe Canadian Solar CS6R 420W delivers 420W versus 400W per panel — 20W 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: TieBoth panels use PERC Mono cell technology. No technology advantage for either product.
Canadian Solar CS6R 420W
The CS6R is Canadian Solar's residential PERC workhorse delivering 420W in a compact, roof-friendly form factor.
Pros
- + Compact residential size
- + Affordable pricing
- + Proven track record
- + Easy installation
Cons
- - Older PERC technology
- - Standard performance
- - Higher degradation
Q CELLS Q.PEAK DUO BLK ML-G10+ 400W
The Q.PEAK DUO BLK is a proven all-black PERC panel from Q CELLS, offering 400W with the same 25-year product warranty.
Pros
- + 25-year product warranty
- + All-black aesthetics
- + Proven PERC reliability
- + Widely available in US
Cons
- - Lower efficiency than N-type
- - Older technology
- - Standard PERC degradation
Choose Canadian Solar CS6R 420W 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 from a bankable Tier 1 brand.
Choose Q CELLS Q.PEAK DUO BLK ML-G10+ 400W If...
- ✓ Long-term warranty protection is a top priority and you plan to stay in your home for 25+ years
- ✓ You want maximum output retention over the system's 25-30 year lifespan
- ✓ Homeowners wanting an attractive, proven panel with extended warranty coverage.
Our Recommendation
The Q CELLS Q.PEAK DUO BLK ML-G10+ 400W is the decisive winner in this solar panel comparison, outperforming the Canadian Solar CS6R 420W in 1 of 5 dimensions. Unless you have a specific requirement that the Canadian Solar CS6R 420W uniquely addresses, the Q CELLS Q.PEAK DUO BLK ML-G10+ 400W is the stronger choice for virtually every installation scenario.
Frequently Asked Questions
Which is better, Canadian Solar CS6R 420W or Q CELLS Q.PEAK DUO BLK ML-G10+ 400W?
The Q CELLS Q.PEAK DUO BLK ML-G10+ 400W wins this comparison by a decisive margin. It offers better long-term durability with 25-year warranty. For most residential installations, the Q CELLS Q.PEAK DUO BLK ML-G10+ 400W is the stronger choice.
Which panel is more efficient, Canadian Solar CS6R 420W or Q CELLS Q.PEAK DUO BLK ML-G10+ 400W?
The Canadian Solar CS6R 420W at 21% module efficiency. Higher efficiency means more watts per square foot of roof space, which is critical for space-constrained installations. The difference of 0.1 percentage points translates to approximately 20W per panel under standard test conditions.
Which has a better warranty, Canadian Solar CS6R 420W or Q CELLS Q.PEAK DUO BLK ML-G10+ 400W?
The Canadian Solar CS6R 420W comes with a 12-year product warranty and 25-year performance guarantee. The Q CELLS Q.PEAK DUO BLK ML-G10+ 400W offers 25-year product and 25-year performance warranties. Q CELLS Q.PEAK DUO BLK ML-G10+ 400W provides 13 additional years of product coverage.
Which panel performs better in hot weather?
The Canadian Solar CS6R 420W has a temperature coefficient of -0.34%/°C and the Q CELLS Q.PEAK DUO BLK ML-G10+ 400W is -0.34%/°C. Both handle heat equally. A lower (less negative) temperature coefficient is better.
How many Canadian Solar CS6R 420W vs Q CELLS Q.PEAK DUO BLK ML-G10+ 400W panels do I need for an 8 kW system?
For an 8 kW system: you need 20 Canadian Solar CS6R 420W panels (420W each) or 20 Q CELLS Q.PEAK DUO BLK ML-G10+ 400W panels (400W each). The Canadian Solar CS6R 420W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026