Canadian Solar CS6R 420W vs First Solar Series 6 Plus 465W
The Canadian Solar CS6R 420W wins this comparison by a narrow margin. It leads in efficiency (21% vs 19.2%) and matches or exceeds on warranty (12 vs 10 years). For most residential installations, the Canadian Solar CS6R 420W is the stronger choice.
Key Differences
- • Canadian Solar CS6R 420W is rated at 420W while First Solar Series 6 Plus 465W is rated at 465W, a 45W difference.
- • Canadian Solar CS6R 420W achieves 21% efficiency vs 19.2% for the other, a 1.8 percentage point gap.
- • Canadian Solar CS6R 420W comes with a 12-year product warranty vs 10 years for the other.
- • First Solar Series 6 Plus 465W has a superior temperature coefficient of -0.28%/°C vs -0.34%/°C, retaining more power in hot climates.
- • Canadian Solar CS6R 420W uses PERC Mono cells while First Solar Series 6 Plus 465W uses CdTe (Cadmium Telluride) cells, representing different technology generations.
Specifications Breakdown
Module Efficiency
The Canadian Solar CS6R 420W achieves 21% module efficiency compared to First Solar Series 6 Plus 465W's 19.2%, meaning Canadian Solar CS6R 420W converts 1.8 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 First Solar Series 6 Plus 465W produces 187.9 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 First Solar Series 6 Plus 465W delivers 465W per panel versus 420W for the Canadian Solar CS6R 420W, a 45W difference per module. To build an 8 kW residential system, you would need 20 Canadian Solar CS6R 420W panels or 18 First Solar Series 6 Plus 465W 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 First Solar Series 6 Plus 465W has a temperature coefficient of -0.28%/°C versus -0.34%/°C for the Canadian Solar CS6R 420W. On a hot summer day when cell temperature reaches 65°C (40°C above the 25°C STC baseline), the First Solar Series 6 Plus 465W retains 94.4% 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 Canadian Solar CS6R 420W is backed by a 12-year product warranty and 25-year performance guarantee, while the First Solar Series 6 Plus 465W offers 10-year product and 30-year performance coverage. The Canadian Solar CS6R 420W 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 Canadian Solar CS6R 420W; 1.5% first year then 0.5%/year for First Solar Series 6 Plus 465W), after 25 years the Canadian Solar CS6R 420W should retain approximately 86.5% of original output versus 86.5% for the First Solar Series 6 Plus 465W. The end-of-life output levels are closely matched.
Physical Dimensions & Weight
The Canadian Solar CS6R 420W measures 1722×1134×30mm and weighs 21 kg, while the First Solar Series 6 Plus 465W measures 2009×1232×49mm at 34.5 kg. 1.95 m² of panel area for the Canadian Solar CS6R 420W versus 2.48 m² for the First Solar Series 6 Plus 465W. The Canadian Solar CS6R 420W is 13.5 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 270 kg. The more compact Canadian Solar CS6R 420W may be easier to fit on irregularly shaped or space-limited rooftops.
Specification Comparison
| Specification | Canadian Solar CS6R 420W | First Solar Series 6 Plus 465W |
|---|---|---|
| Power | 420W | 465W |
| Efficiency | 21% | 19.2% |
| Power Density | 20.0 W/sq ft | 17.5 W/sq ft |
| Cell Type | PERC Mono | CdTe (Cadmium Telluride) |
| Bifacial | No | No |
| Weight | 21 kg | 34.5 kg |
| Temp Coefficient | -0.34%/°C | -0.28%/°C |
| Snow Load | 5400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 4000 Pa |
| Product Warranty | 12 years | 10 years |
| Performance Warranty | 25 years | 30 years |
| Degradation (Year 1) | 1.5% | 1.5% |
| Annual Degradation | 0.5% | 0.5% |
| 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 19.2% — a 1.8 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 1.4 kW more total system capacity, or 7 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: First Solar Series 6 Plus 465WThe First Solar Series 6 Plus 465W has a better temperature coefficient of -0.28%/°C versus -0.34%/°C. On a 45°C summer day (20°C above STC), the winner retains 94.4% of rated power versus 93.2%. This is a meaningful difference in hot states like Arizona, Texas, and Florida.
3. Durability & Warranty
Winner: Canadian Solar CS6R 420WCanadian Solar CS6R 420W leads with a 12-year product warranty versus 10 years. After 25 years, expect 86.5% vs 86.5% of original output for Canadian Solar CS6R 420W and First Solar Series 6 Plus 465W respectively.
4. Power Output
Winner: First Solar Series 6 Plus 465WThe First Solar Series 6 Plus 465W delivers 465W versus 420W per panel — 45W more. For an 8 kW system, you need 18 panels with the higher-wattage option versus 20 panels, saving 2 panels and the associated racking and labor costs.
5. Cell Technology
Winner: First Solar Series 6 Plus 465WThe Canadian Solar CS6R 420W uses PERC Mono: PERC (Passivated Emitter Rear Cell) is the current mainstream technology, offering good efficiency at the lowest manufacturing cost. The First Solar Series 6 Plus 465W uses CdTe (Cadmium Telluride): CdTe (Cadmium Telluride). CdTe (Cadmium Telluride) represents a newer generation technology with a longer performance runway as manufacturing matures.
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
First Solar Series 6 Plus 465W
The Series 6 Plus delivers 465W using First Solar's proven CdTe thin-film technology, manufactured in the United States.
Pros
- + Proven US thin-film technology
- + Excellent temperature coefficient
- + Environmentally responsible
- + Strong bankability
Cons
- - Lower efficiency
- - Very heavy panel
- - Not suitable for residential
Choose Canadian Solar CS6R 420W If...
- ✓ Your roof space is limited and you need maximum power per panel
- ✓ Long-term warranty protection is a top priority and you plan to stay in your home for 12+ years
- ✓ Budget residential installations from a bankable Tier 1 brand.
Choose First Solar Series 6 Plus 465W If...
- ✓ 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
- ✓ Large commercial and utility projects wanting proven US thin-film technology.
Our Recommendation
Both the Canadian Solar CS6R 420W and First Solar Series 6 Plus 465W are excellent solar panel options, and the margin between them is narrow. The Canadian Solar CS6R 420W wins 2 of 5 comparison dimensions by a slim margin. Your decision may come down to local pricing, installer availability, and which specific performance metrics matter most for your project. Either product is a solid investment.
Frequently Asked Questions
Which is better, Canadian Solar CS6R 420W or First Solar Series 6 Plus 465W?
The Canadian Solar CS6R 420W wins this comparison by a narrow margin. It leads in efficiency (21% vs 19.2%) and matches or exceeds on warranty (12 vs 10 years). For most residential installations, the Canadian Solar CS6R 420W is the stronger choice.
Which panel is more efficient, Canadian Solar CS6R 420W or First Solar Series 6 Plus 465W?
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 1.8 percentage points translates to approximately 45W per panel under standard test conditions.
Which has a better warranty, Canadian Solar CS6R 420W or First Solar Series 6 Plus 465W?
The Canadian Solar CS6R 420W comes with a 12-year product warranty and 25-year performance guarantee. The First Solar Series 6 Plus 465W offers 10-year product and 30-year performance warranties. Canadian Solar CS6R 420W provides 2 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 First Solar Series 6 Plus 465W is -0.28%/°C. First Solar Series 6 Plus 465W 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 First Solar Series 6 Plus 465W 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 18 First Solar Series 6 Plus 465W panels (465W each). The First Solar Series 6 Plus 465W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026