Canadian Solar CS6R 420W vs Silfab SIL-370-BK 370W
The Silfab SIL-370-BK 370W wins this comparison by a decisive margin. It offers better long-term durability with 25-year warranty. For most residential installations, the Silfab SIL-370-BK 370W is the stronger choice.
Key Differences
- • Canadian Solar CS6R 420W is rated at 420W while Silfab SIL-370-BK 370W is rated at 370W, a 50W difference.
- • Canadian Solar CS6R 420W achieves 21% efficiency vs 20.4% for the other, a 0.6 percentage point gap.
- • Silfab SIL-370-BK 370W comes with a 25-year product warranty vs 12 years for the other.
- • Canadian Solar CS6R 420W has a superior temperature coefficient of -0.34%/°C vs -0.35%/°C, retaining more power in hot climates.
Specifications Breakdown
Module Efficiency
The Canadian Solar CS6R 420W achieves 21% module efficiency compared to Silfab SIL-370-BK 370W's 20.4%, meaning Canadian Solar CS6R 420W converts 0.6 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 Silfab SIL-370-BK 370W produces 189.5 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 Canadian Solar CS6R 420W delivers 420W per panel versus 370W for the Silfab SIL-370-BK 370W, a 50W difference per module. To build an 8 kW residential system, you would need 20 Canadian Solar CS6R 420W panels or 22 Silfab SIL-370-BK 370W panels. Choosing the higher-wattage option saves 2 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 Canadian Solar CS6R 420W has a temperature coefficient of -0.34%/°C versus -0.35%/°C for the Silfab SIL-370-BK 370W. On a hot summer day when cell temperature reaches 65°C (40°C above the 25°C STC baseline), the Canadian Solar CS6R 420W retains 93.2% of its rated power while the other retains 93.0%. 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 Canadian Solar CS6R 420W is backed by a 12-year product warranty and 25-year performance guarantee, while the Silfab SIL-370-BK 370W offers 25-year product and 25-year performance coverage. The Silfab SIL-370-BK 370W 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 Silfab SIL-370-BK 370W), after 25 years the Canadian Solar CS6R 420W should retain approximately 86.5% of original output versus 89.4% for the Silfab SIL-370-BK 370W. 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 Silfab SIL-370-BK 370W measures 1722×1134×30mm at 19.5 kg. 1.95 m² of panel area for the Canadian Solar CS6R 420W versus 1.95 m² for the Silfab SIL-370-BK 370W. 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 | Silfab SIL-370-BK 370W |
|---|---|---|
| Power | 420W | 370W |
| Efficiency | 21% | 20.4% |
| Power Density | 20.0 W/sq ft | 17.6 W/sq ft |
| Cell Type | PERC Mono | PERC Mono |
| Bifacial | No | No |
| Weight | 21 kg | 19.5 kg |
| Temp Coefficient | -0.34%/°C | -0.35%/°C |
| Snow Load | 5400 Pa | 2400 Pa |
| Wind Load | 2400 Pa | 2400 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 | United States |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: Canadian Solar CS6R 420WThe Canadian Solar CS6R 420W achieves 21% efficiency versus 20.4% — a 0.6 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 1.5 kW more total system capacity, or 7 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: Canadian Solar CS6R 420WThe Canadian Solar CS6R 420W has a better temperature coefficient of -0.34%/°C versus -0.35%/°C. On a 45°C summer day (20°C above STC), the winner retains 93.2% of rated power versus 93.0%. The difference is modest but accumulates over 25 years of summer production.
3. Durability & Warranty
Winner: Silfab SIL-370-BK 370WSilfab SIL-370-BK 370W leads with a 25-year product warranty versus 12 years. Silfab SIL-370-BK 370W 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 Silfab SIL-370-BK 370W respectively.
4. Power Output
Winner: Canadian Solar CS6R 420WThe Canadian Solar CS6R 420W delivers 420W versus 370W per panel — 50W more. For an 8 kW system, you need 20 panels with the higher-wattage option versus 22 panels, saving 2 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
Silfab SIL-370-BK 370W
The SIL-370-BK is Silfab's entry-level US-made all-black panel delivering 370W for budget-conscious domestic installations.
Pros
- + Made in USA
- + All-black design
- + 25-year warranty
- + ARRA compliant
Cons
- - Lower wattage
- - Basic PERC technology
- - Less competitive efficiency
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
- ✓ You live in a hot climate (Arizona, Texas, Florida) where heat performance matters
- ✓ Budget residential installations from a bankable Tier 1 brand.
Choose Silfab SIL-370-BK 370W 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
- ✓ Government or institutional projects requiring ARRA/Buy America compliance.
Our Recommendation
The Silfab SIL-370-BK 370W 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 Silfab SIL-370-BK 370W is the stronger choice for virtually every installation scenario.
Frequently Asked Questions
Which is better, Canadian Solar CS6R 420W or Silfab SIL-370-BK 370W?
The Silfab SIL-370-BK 370W wins this comparison by a decisive margin. It offers better long-term durability with 25-year warranty. For most residential installations, the Silfab SIL-370-BK 370W is the stronger choice.
Which panel is more efficient, Canadian Solar CS6R 420W or Silfab SIL-370-BK 370W?
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 0.6 percentage points translates to approximately 50W per panel under standard test conditions.
Which has a better warranty, Canadian Solar CS6R 420W or Silfab SIL-370-BK 370W?
The Canadian Solar CS6R 420W comes with a 12-year product warranty and 25-year performance guarantee. The Silfab SIL-370-BK 370W offers 25-year product and 25-year performance warranties. Silfab SIL-370-BK 370W 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 Silfab SIL-370-BK 370W is -0.35%/°C. Canadian Solar CS6R 420W retains more power in heat — important in states like Arizona, Texas, and Florida. A lower (less negative) temperature coefficient is better.
How many Canadian Solar CS6R 420W vs Silfab SIL-370-BK 370W 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 22 Silfab SIL-370-BK 370W panels (370W each). The Canadian Solar CS6R 420W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026