--- title: "Canadian Solar CS7N-640MB-AG vs Canadian Solar CS7N-665MB-AG - Solar Panel Comparison | ComparePV" description: "Compare Canadian Solar CS7N-640MB-AG vs Canadian Solar CS7N-665MB-AG 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-cs7n-640mb-ag/csi-solar-co-ltd-canadian-solar-cs7n-665mb-ag" updated: 2026-09-11 --- # Canadian Solar CS7N-640MB-AG vs Canadian Solar CS7N-665MB-AG 665MB-AG leads on the differences that matter The largest is module efficiency: 0.80 pp more efficient. 13 of 19 comparable parameters are identical. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Canadian Solar CS7N-640MB-AG](https://comparepv.com/panel/csi-solar-co-ltd-canadian-solar-cs7n-640mb-ag) | [Canadian Solar CS7N-665MB-AG](https://comparepv.com/panel/csi-solar-co-ltd-canadian-solar-cs7n-665mb-ag) | | Manufacturer | Canadian Solar | Canadian Solar | | Power | 640 Wp | 665 Wp | | Efficiency | 20.60 % | 21.40 % | | Technology | PERC | PERC | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | 640MB-AG | 665MB-AG | Difference | | --- | --- | --- | --- | | Module efficiency | 20.60 % | 21.40 % | +0.80 pp for 665MB-AG | | Power density | 206.0 Wp/m² | 214.1 Wp/m² | +8.0 Wp/m² for 665MB-AG | | Rated power | 640 Wp | 665 Wp | +25 W for 665MB-AG | | Weight per kWp | 59.2 kg/kWp | 57.0 kg/kWp | -2.2 kg/kWp for 665MB-AG | | Open-circuit voltage | 44.60 V | 45.60 V | 1.00 V apart | | Voltage at max power | 37.50 V | 38.50 V | 1.00 V apart | ## Every compared parameter | Parameter | 640MB-AG | 665MB-AG | | --- | --- | --- | | Rated power | 640 Wp | 665 Wp | | Module efficiency | 20.60 % | 21.40 % | | Power density | 206.0 Wp/m² | 214.1 Wp/m² | | Open-circuit voltage | 44.60 V | 45.60 V | | Voltage at max power | 37.50 V | 38.50 V | | Short-circuit current | 18.31 A | 18.51 A | | Current at max power | 17.07 A | 17.28 A | | Temperature coefficient | -0.340 %/°C | -0.340 %/°C | | Dimensions | 2384x1303x35 mm | 2384x1303x35 mm | | Module area | 3.106 m² | 3.106 m² | | Weight | 37.9 kg | 37.9 kg | | Weight per kWp | 59.2 kg/kWp | 57.0 kg/kWp | | Product warranty | 12 yrs | 12 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.45 %/yr | 0.45 %/yr | | Cell technology | PERC | PERC | | 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 (-0.340 %/°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, 640MB-AG:** 21,076 kWh - **Cumulative output, 665MB-AG:** 21,899 kWh - **Gap:** 823 kWh ## Output when hot | Condition | Cell temperature | 640MB-AG | 665MB-AG | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 640 W | 665 W | 100.0% of rated power | | Cool, bright day | 40 °C | 607 W | 631 W | 94.9% of rated power | | Typical summer roof | 55 °C | 575 W | 597 W | 89.8% of rated power | | Hot roof | 70 °C | 542 W | 563 W | 84.7% of rated power | ## Against the whole database | Measure | 640MB-AG | 665MB-AG | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #11,093 | #8,323 | 14,005 | 665MB-AG leads by 2,770 places | | Power density | #11,100 | #8,250 | 14,005 | 665MB-AG leads by 2,850 places | | Heat behaviour | #8,778 | #8,778 | 14,005 | Tied - the same position in the database | | Weight | #12,053 | #10,995 | 14,005 | 665MB-AG leads by 1,058 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #4,656 | #2,833 | 14,005 | 665MB-AG leads by 1,823 places | ## Questions ### Which panel is better: Canadian Solar CS7N-640MB-AG or Canadian Solar CS7N-665MB-AG? According to our database: **Canadian Solar CS7N-665MB-AG** has higher module efficiency (**21.40%** vs **20.60%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Canadian Solar CS7N-640MB-AG and Canadian Solar CS7N-665MB-AG? **Canadian Solar CS7N-640MB-AG** has a module efficiency of **20.60%**, while **Canadian Solar CS7N-665MB-AG** is **21.40%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Canadian Solar CS7N-640MB-AG use vs Canadian Solar CS7N-665MB-AG? **Canadian Solar CS7N-640MB-AG** uses **PERC** cells; **Canadian Solar CS7N-665MB-AG** uses **PERC**. 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 CS7N-640MB-AG and Canadian Solar CS7N-665MB-AG? **Canadian Solar CS7N-640MB-AG** has a **30 years** power warranty; **Canadian Solar CS7N-665MB-AG** 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 CS7N-640MB-AG and Canadian Solar CS7N-665MB-AG bifacial panels? Both **Canadian Solar CS7N-640MB-AG** and **Canadian Solar CS7N-665MB-AG** 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 CS7N-640MB-AG vs Canadian Solar CS7N-670MB-AG](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs7n-640mb-ag/csi-solar-co-ltd-cs7n-670mb-ag) - 7 differences, the largest is module efficiency - [Canadian Solar CS7N-640MB-AG vs Canadian Solar CS7N-660MB-AG](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs7n-640mb-ag/csi-solar-co-ltd-canadian-solar-cs7n-660mb-ag) - 3 differences, the largest is module efficiency - [Canadian Solar CS7N-640MB-AG vs Canadian Solar CS7N-655MB-AG](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs7n-640mb-ag/csi-solar-co-ltd-canadian-solar-cs7n-655mb-ag) - 3 differences, the largest is module efficiency - [Canadian Solar CS7N-640MB-AG vs Canadian Solar CS7N-650MB-AG](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs7n-640mb-ag/csi-solar-co-ltd-canadian-solar-cs7n-650mb-ag) - 3 differences, the largest is module efficiency - [Canadian Solar CS7N-640MB-AG vs Canadian Solar CS7N-645MB-AG](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs7n-640mb-ag/csi-solar-co-ltd-canadian-solar-cs7n-645mb-ag) - One difference: module efficiency - [Canadian Solar CS7N-640MB-AG vs Canadian Solar CS7L-610MB-AG](https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs7n-640mb-ag/csi-solar-co-ltd-canadian-solar-cs7l-610mb-ag) - 10 differences, the largest is module efficiency --- Source: https://comparepv.com/compare/csi-solar-co-ltd-canadian-solar-cs7n-640mb-ag/csi-solar-co-ltd-canadian-solar-cs7n-665mb-ag 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.