--- title: "Canadian Solar CS6.2-66HB-635 vs Canadian Solar CS6.2-66HB-640 - Solar Panel Comparison | ComparePV" description: "Compare Canadian Solar CS6.2-66HB-635 vs Canadian Solar CS6.2-66HB-640 side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-635/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-640" image: "https://comparepv.com/og/compare/panels/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-635/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-640.png" updated: 2026-09-11 --- # Canadian Solar CS6.2-66HB-635 vs Canadian Solar CS6.2-66HB-640 640 leads on the differences that matter The largest is module efficiency: 0.20 pp more efficient. 18 of 19 comparable parameters are identical. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Canadian Solar CS6.2-66HB-635](https://comparepv.com/panel/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-635) | [Canadian Solar CS6.2-66HB-640](https://comparepv.com/panel/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-640) | | Manufacturer | Canadian Solar | Canadian Solar | | Power | 635 Wp | 640 Wp | | Efficiency | 23.50 % | 23.70 % | | Technology | HJT | HJT | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | 635 | 640 | Difference | | --- | --- | --- | --- | | Module efficiency | 23.50 % | 23.70 % | +0.20 pp for 640 | ## Every compared parameter | Parameter | 635 | 640 | | --- | --- | --- | | Rated power | 635 Wp | 640 Wp | | Module efficiency | 23.50 % | 23.70 % | | Power density | 235.1 Wp/m² | 236.9 Wp/m² | | Open-circuit voltage | 50.30 V | 50.40 V | | Voltage at max power | 42.70 V | 42.70 V | | Short-circuit current | 15.92 A | 16.01 A | | Current at max power | 14.88 A | 14.99 A | | Temperature coefficient | -0.240 %/°C | -0.240 %/°C | | Dimensions | 2382x1134x30 mm | 2382x1134x30 mm | | Module area | 2.701 m² | 2.701 m² | | Weight | 32.8 kg | 32.8 kg | | Weight per kWp | 51.7 kg/kWp | 51.2 kg/kWp | | Product warranty | 15 yrs | 15 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.30 %/yr | 0.30 %/yr | | Cell technology | HJT | HJT | | Cell type | Monocrystalline | Monocrystalline | | Cell count | 132 | 132 | | Bifacial | Yes | Yes | ## Thirty-year yield Each panel's own declared degradation curve, at 1,200 kWh/kWp a year Same temp coeff. for both panels (-0.240 %/°C), so a warmer roof scales both curves by the same factor: the totals fall together and neither panel gains on the other. - **Cumulative output, 635:** 21,637 kWh - **Cumulative output, 640:** 21,807 kWh - **Gap:** 170 kWh ## Output when hot | Condition | Cell temperature | 635 | 640 | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 635 W | 640 W | 100.0% of rated power | | Cool, bright day | 40 °C | 612 W | 617 W | 96.4% of rated power | | Typical summer roof | 55 °C | 589 W | 594 W | 92.8% of rated power | | Hot roof | 70 °C | 566 W | 571 W | 89.2% of rated power | ## Against the whole database | Measure | 635 | 640 | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #749 | #549 | 14,129 | 640 leads by 200 places | | Power density | #777 | #553 | 14,129 | 640 leads by 224 places | | Heat behaviour | #13 | #13 | 14,129 | Tied - the same position in the database | | Weight | #5,050 | #4,663 | 14,129 | 640 leads by 387 places | | Warranty | #21 | #21 | 14,129 | Tied - the same position in the database | | Overall | #1,463 | #1,276 | 14,129 | 640 leads by 187 places | ## Questions ### Which panel is better: Canadian Solar CS6.2-66HB-635 or Canadian Solar CS6.2-66HB-640? According to our database: **Canadian Solar CS6.2-66HB-640** has higher module efficiency (**23.70%** vs **23.50%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Canadian Solar CS6.2-66HB-635 and Canadian Solar CS6.2-66HB-640? **Canadian Solar CS6.2-66HB-635** has a module efficiency of **23.50%**, while **Canadian Solar CS6.2-66HB-640** is **23.70%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Canadian Solar CS6.2-66HB-635 use vs Canadian Solar CS6.2-66HB-640? **Canadian Solar CS6.2-66HB-635** uses **HJT** cells; **Canadian Solar CS6.2-66HB-640** uses **HJT**. Modern **n-type** technologies (**TOPCon**, **HJT**, BC) typically deliver higher efficiency and lower degradation compared to older **PERC** (p-type) cells. ### What is the warranty on Canadian Solar CS6.2-66HB-635 and Canadian Solar CS6.2-66HB-640? **Canadian Solar CS6.2-66HB-635** has a **30 years** power warranty; **Canadian Solar CS6.2-66HB-640** has a **30 years** power warranty. The power warranty guarantees a minimum percentage of rated output at the end of the warranty period (typically 80**-87%**). Product (materials) warranties are usually shorter. ### Are Canadian Solar CS6.2-66HB-635 and Canadian Solar CS6.2-66HB-640 bifacial panels? Both **Canadian Solar CS6.2-66HB-635** and **Canadian Solar CS6.2-66HB-640** are bifacial - they capture reflected light from the ground, which can add 5**-15%** more annual energy on ground-mount or elevated rooftop installations with a light surface beneath. ## Related comparisons - [Canadian Solar CS6.2-66HB-635 vs Canadian Solar CS6.2-66HB-645](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-635/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-645) - 3 differences, the largest is module efficiency - [Canadian Solar CS6.2-66HB-635 vs Canadian Solar CS6.2-66HB-630](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-635/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-630) - One difference: module efficiency - [Canadian Solar CS6.2-66HB-635 vs Canadian Solar CS6.2-66HB-625](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-635/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-625) - 3 differences, the largest is module efficiency - [Canadian Solar CS6.2-66HB-635 vs Canadian Solar CS6.2-66HB-620](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-635/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-620) - 3 differences, the largest is module efficiency - [Canadian Solar CS6.2-66HB-635 vs Canadian Solar CS7N-730TB-AG](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-635/csi-solar-co-ltd-canadian-solar-cs7n-730tb-ag) - 12 differences, the largest is temperature coefficient - [Canadian Solar CS6.2-66HB-635 vs Canadian Solar CS7N-725TB-AG](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-635/csi-solar-co-ltd-canadian-solar-cs7n-725tb-ag) - 13 differences, the largest is temperature coefficient --- Source: https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-635/csi-solar-co-ltd-canadian-solar-cs6-2-66hb-640 Not in this file, on the page: the thirty-year yield curve year by year at a cell temperature you pick and a written summary generated on request.