--- title: "Longi Solar LR7-72HVD-640M vs Longi Solar LR7-72HVD-660M - Solar Panel Comparison | ComparePV" description: "Compare Longi Solar LR7-72HVD-640M vs Longi Solar LR7-72HVD-660M side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/longi-lr7-72hvd-640m/longi-lr7-72hvd-660m" updated: 2026-09-11 --- # Longi Solar LR7-72HVD-640M vs Longi Solar LR7-72HVD-660M 660M leads on the differences that matter The largest is module efficiency: 0.70 pp more efficient. 16 of 19 comparable parameters are identical. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Longi Solar LR7-72HVD-640M](https://comparepv.com/panel/longi-lr7-72hvd-640m) | [Longi Solar LR7-72HVD-660M](https://comparepv.com/panel/longi-lr7-72hvd-660m) | | Manufacturer | Longi Solar | Longi Solar | | Power | 640 Wp | 660 Wp | | Efficiency | 23.70 % | 24.40 % | | Technology | N-type | N-type | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | 640M | 660M | Difference | | --- | --- | --- | --- | | Module efficiency | 23.70 % | 24.40 % | +0.70 pp for 660M | | Power density | 236.9 Wp/m² | 244.3 Wp/m² | +7.4 Wp/m² for 660M | | Rated power | 640 Wp | 660 Wp | +20 W for 660M | ## Every compared parameter | Parameter | 640M | 660M | | --- | --- | --- | | Rated power | 640 Wp | 660 Wp | | Module efficiency | 23.70 % | 24.40 % | | Power density | 236.9 Wp/m² | 244.3 Wp/m² | | Open-circuit voltage | 54.02 V | 54.42 V | | Voltage at max power | 44.67 V | 45.07 V | | Short-circuit current | 14.98 A | 15.30 A | | Current at max power | 14.33 A | 14.65 A | | Temperature coefficient | -0.260 %/°C | -0.260 %/°C | | Dimensions | 2382x1134x30 mm | 2382x1134x30 mm | | Module area | 2.701 m² | 2.701 m² | | Weight | 33.5 kg | 33.5 kg | | Weight per kWp | 52.3 kg/kWp | 50.8 kg/kWp | | Product warranty | 15 yrs | 15 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.35 %/yr | 0.35 %/yr | | Cell technology | N-type | N-type | | Cell type | Monocrystalline | Monocrystalline | | Cell count | 144 | 144 | | 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 (-0.260 %/°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, 640M:** 21,640 kWh - **Cumulative output, 660M:** 22,317 kWh - **Gap:** 677 kWh ## Output when hot | Condition | Cell temperature | 640M | 660M | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 640 W | 660 W | 100.0% of rated power | | Cool, bright day | 40 °C | 615 W | 634 W | 96.1% of rated power | | Typical summer roof | 55 °C | 590 W | 609 W | 92.2% of rated power | | Hot roof | 70 °C | 565 W | 583 W | 88.3% of rated power | ## Against the whole database | Measure | 640M | 660M | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #517 | #99 | 14,005 | 660M leads by 418 places | | Power density | #521 | #88 | 14,005 | 660M leads by 433 places | | Heat behaviour | #511 | #511 | 14,005 | Tied - the same position in the database | | Weight | #5,829 | #4,172 | 14,005 | 660M leads by 1,657 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #1,271 | #576 | 14,005 | 660M leads by 695 places | ## Questions ### Which panel is better: Longi Solar LR7-72HVD-640M or Longi Solar LR7-72HVD-660M? According to our database: **Longi Solar LR7-72HVD-660M** has higher module efficiency (**24.40%** vs **23.70%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Longi Solar LR7-72HVD-640M and Longi Solar LR7-72HVD-660M? **Longi Solar LR7-72HVD-640M** has a module efficiency of **23.70%**, while **Longi Solar LR7-72HVD-660M** is **24.40%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Longi Solar LR7-72HVD-640M use vs Longi Solar LR7-72HVD-660M? **Longi Solar LR7-72HVD-640M** uses **N-type** cells; **Longi Solar LR7-72HVD-660M** uses **N-type**. 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 Longi Solar LR7-72HVD-640M and Longi Solar LR7-72HVD-660M? **Longi Solar LR7-72HVD-640M** has a **30 years** power warranty; **Longi Solar LR7-72HVD-660M** 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 Longi Solar LR7-72HVD-640M and Longi Solar LR7-72HVD-660M bifacial panels? Both **Longi Solar LR7-72HVD-640M** and **Longi Solar LR7-72HVD-660M** 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 - [Longi Solar LR7-72HVD-640M vs Longi Solar LR7-72HVD-665M](https://comparepv.com/compare/longi-lr7-72hvd-640m/longi-lr7-72hvd-665m) - 3 differences, the largest is module efficiency - [Longi Solar LR7-72HVD-640M vs Longi Solar LR7-72HVD-655M](https://comparepv.com/compare/longi-lr7-72hvd-640m/longi-lr7-72hvd-655m) - 3 differences, the largest is module efficiency - [Longi Solar LR7-72HVD-640M vs Longi Solar LR7-72HVD-650M](https://comparepv.com/compare/longi-lr7-72hvd-640m/longi-lr7-72hvd-650m) - 3 differences, the largest is module efficiency - [Longi Solar LR7-72HVD-640M vs Longi Solar LR7-72HVD-645M](https://comparepv.com/compare/longi-lr7-72hvd-640m/longi-lr7-72hvd-645m) - One difference: module efficiency - [Longi Solar LR7-72HVD-640M vs Longi Solar LR7-72HVHF-670M](https://comparepv.com/compare/longi-lr7-72hvd-640m/longi-lr7-72hvhf-670m) - 8 differences, the largest is module efficiency - [Longi Solar LR7-72HVD-640M vs Longi Solar LR8-66HYD-670M](https://comparepv.com/compare/longi-lr7-72hvd-640m/longi-lr8-66hyd-670m) - 11 differences, the largest is module efficiency --- Source: https://comparepv.com/compare/longi-lr7-72hvd-640m/longi-lr7-72hvd-660m 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.