Canadian Solar CS6R 420W vs Waaree WS-440
The Waaree WS-440 wins this comparison by a clear margin. It leads in efficiency (21.8% vs 21%) and matches or exceeds on warranty (12 vs 12 years). For most residential installations, the Waaree WS-440 is the stronger choice.
Key Differences
- • Canadian Solar CS6R 420W is rated at 420W while Waaree WS-440 is rated at 440W, a 20W difference.
- • Waaree WS-440 achieves 21.8% efficiency vs 21% for the other, a 0.8 percentage point gap.
- • Both carry matching 12-year product warranties.
- • Waaree WS-440 has a superior temperature coefficient of -0.3%/°C vs -0.34%/°C, retaining more power in hot climates.
- • Canadian Solar CS6R 420W uses PERC Mono cells while Waaree WS-440 uses TOPCon N-type cells, representing different technology generations.
Specifications Breakdown
Module Efficiency
The Waaree WS-440 achieves 21.8% module efficiency compared to Canadian Solar CS6R 420W's 21%, meaning Waaree WS-440 converts 0.8 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 Waaree WS-440 produces 225.3 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 Waaree WS-440 delivers 440W per panel versus 420W for the Canadian Solar CS6R 420W, a 20W difference per module. To build an 8 kW residential system, you would need 20 Canadian Solar CS6R 420W panels or 19 Waaree WS-440 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 Waaree WS-440 has a temperature coefficient of -0.3%/°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 Waaree WS-440 retains 94.0% of its rated power while the other retains 93.2%. 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 Canadian Solar CS6R 420W is backed by a 12-year product warranty and 25-year performance guarantee, while the Waaree WS-440 offers 12-year product and 25-year performance coverage. Both offer identical product warranty duration. 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 Waaree WS-440), after 25 years the Canadian Solar CS6R 420W should retain approximately 86.5% of original output versus 89.4% for the Waaree WS-440. 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 Waaree WS-440 measures 1722×1134×30mm at 21.5 kg. 1.95 m² of panel area for the Canadian Solar CS6R 420W versus 1.95 m² for the Waaree WS-440. 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 | Waaree WS-440 |
|---|---|---|
| Power | 420W | 440W |
| Efficiency | 21% | 21.8% |
| Power Density | 20.0 W/sq ft | 20.9 W/sq ft |
| Cell Type | PERC Mono | TOPCon N-type |
| Bifacial | No | No |
| Weight | 21 kg | 21.5 kg |
| Temp Coefficient | -0.34%/°C | -0.3%/°C |
| Snow Load | 5400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 2400 Pa |
| Product Warranty | 12 years | 12 years |
| Performance Warranty | 25 years | 25 years |
| Degradation (Year 1) | 1.5% | 1% |
| Annual Degradation | 0.5% | 0.4% |
| Country | China | India |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: Waaree WS-440The Waaree WS-440 achieves 21.8% efficiency versus 21% — a 0.8 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: Waaree WS-440The Waaree WS-440 has a better temperature coefficient of -0.3%/°C versus -0.34%/°C. On a 45°C summer day (20°C above STC), the winner retains 94.0% of rated power versus 93.2%. The difference is modest but accumulates over 25 years of summer production.
3. Durability & Warranty
Winner: Waaree WS-440Waaree WS-440 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 Waaree WS-440 respectively.
4. Power Output
Winner: Waaree WS-440The Waaree WS-440 delivers 440W versus 420W per panel — 20W more. For an 8 kW system, you need 19 panels with the higher-wattage option versus 20 panels, saving 1 panels and the associated racking and labor costs.
5. Cell Technology
Winner: Waaree WS-440The 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 Waaree WS-440 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.
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
Waaree WS-440
The Waaree WS-440 is a 440W residential-format TOPCon N-type panel in the standard 108-cell configuration, manufactured at Waaree's state-of-the-art facilities in Gujarat, India. At 21.8% efficiency, it competes directly with Chinese TOPCon panels while offering Indian supply chain diversification. The standard 1722 x 1134mm form factor ensures compatibility with all major racking systems. Waaree's rapidly expanding US distribution makes this one of the most accessible Indian-made panels in the North American market.
Pros
- + Indian-manufactured — non-Chinese supply chain alternative
- + 21.8% efficiency competitive with Chinese TOPCon leaders
- + Standard 108-cell residential format — universal racking compatibility
- + -0.30%/°C temp coefficient for hot climate performance
- + Highly competitive pricing — among the lowest-cost TOPCon panels
- + Waaree's expanding US distribution improves availability
Cons
- - 12-year product warranty shorter than 25-year leaders
- - Indian manufacturing quality perception still developing vs established brands
- - US installer familiarity and support network still growing
- - No bifacial option in this residential format
Choose Canadian Solar CS6R 420W If...
- ✓ Budget residential installations from a bankable Tier 1 brand.
Choose Waaree WS-440 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 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
We recommend the Waaree WS-440 for most buyers in this comparison. It wins 5 of 5 key dimensions and offers a clear advantage in the metrics that matter most for a solar panel purchase. The Canadian Solar CS6R 420W remains a good product, but the Waaree WS-440 delivers better overall value for the majority of installations.
Frequently Asked Questions
Which is better, Canadian Solar CS6R 420W or Waaree WS-440?
The Waaree WS-440 wins this comparison by a clear margin. It leads in efficiency (21.8% vs 21%) and matches or exceeds on warranty (12 vs 12 years). For most residential installations, the Waaree WS-440 is the stronger choice.
Which panel is more efficient, Canadian Solar CS6R 420W or Waaree WS-440?
The Waaree WS-440 at 21.8% module efficiency. Higher efficiency means more watts per square foot of roof space, which is critical for space-constrained installations. The difference of 0.8 percentage points translates to approximately 20W per panel under standard test conditions.
Which has a better warranty, Canadian Solar CS6R 420W or Waaree WS-440?
The Canadian Solar CS6R 420W comes with a 12-year product warranty and 25-year performance guarantee. The Waaree WS-440 offers 12-year product and 25-year performance warranties. Both offer identical warranty terms.
Which panel performs better in hot weather?
The Canadian Solar CS6R 420W has a temperature coefficient of -0.34%/°C and the Waaree WS-440 is -0.3%/°C. Waaree WS-440 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 Waaree WS-440 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 19 Waaree WS-440 panels (440W each). The Waaree WS-440 requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026