--- title: "Longi Solar LR7-72HVDF-645M vs Longi Solar LR8-66HYD-670M - Solar Panel Comparison | ComparePV" description: "Compare Longi Solar LR7-72HVDF-645M vs Longi Solar LR8-66HYD-670M side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/longi-lr7-72hvdf-645m/longi-lr8-66hyd-670m" updated: 2026-09-11 --- # Longi Solar LR7-72HVDF-645M vs Longi Solar LR8-66HYD-670M LR8-66HYD-670M leads on the differences that matter The largest is module efficiency: 0.90 pp more efficient. 8 of 18 comparable parameters are identical, with 1 more left out because at least one datasheet does not publish it. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Longi Solar LR7-72HVDF-645M](https://comparepv.com/panel/longi-lr7-72hvdf-645m) | [Longi Solar LR8-66HYD-670M](https://comparepv.com/panel/longi-lr8-66hyd-670m) | | Manufacturer | Longi Solar | Longi Solar | | Power | 645 Wp | 670 Wp | | Efficiency | 23.90 % | 24.80 % | | Technology | N-type | Back Contact | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | LR7-72HVDF-645M | LR8-66HYD-670M | Difference | | --- | --- | --- | --- | | Module efficiency | 23.90 % | 24.80 % | +0.90 pp for LR8-66HYD-670M | | Power density | 238.8 Wp/m² | 248.0 Wp/m² | +9.3 Wp/m² for LR8-66HYD-670M | | Rated power | 645 Wp | 670 Wp | +25 W for LR8-66HYD-670M | | Product warranty | 15 yrs | 12 yrs | +3 yrs for LR7-72HVDF-645M | | Open-circuit voltage | 54.12 V | 50.12 V | 4.00 V apart | | Short-circuit current | 15.06 A | 16.86 A | 1.80 A apart | | Cell technology | N-type | Back Contact | N-type vs Back Contact | | Cell count | 144 | 132 | 12 cells apart | | Current at max power | 14.41 A | 16.19 A | 1.78 A apart | | Voltage at max power | 44.77 V | 41.38 V | 3.39 V apart | ## Every compared parameter | Parameter | LR7-72HVDF-645M | LR8-66HYD-670M | | --- | --- | --- | | Rated power | 645 Wp | 670 Wp | | Module efficiency | 23.90 % | 24.80 % | | Power density | 238.8 Wp/m² | 248.0 Wp/m² | | Open-circuit voltage | 54.12 V | 50.12 V | | Voltage at max power | 44.77 V | 41.38 V | | Short-circuit current | 15.06 A | 16.86 A | | Current at max power | 14.41 A | 16.19 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 | 51.9 kg/kWp | 50.0 kg/kWp | | Product warranty | 15 yrs | 12 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.35 %/yr | - | | Cell technology | N-type | Back Contact | | Cell type | Monocrystalline | Monocrystalline | | Cell count | 144 | 132 | | Bifacial | Yes | Yes | ## Thirty-year yield A 1.0% first-year loss then 0.40% a year, assumed for both panels, 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, LR7-72HVDF-645M:** 21,641 kWh - **Cumulative output, LR8-66HYD-670M:** 22,480 kWh - **Gap:** 839 kWh ## Output when hot | Condition | Cell temperature | LR7-72HVDF-645M | LR8-66HYD-670M | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 645 W | 670 W | 100.0% of rated power | | Cool, bright day | 40 °C | 620 W | 644 W | 96.1% of rated power | | Typical summer roof | 55 °C | 595 W | 618 W | 92.2% of rated power | | Hot roof | 70 °C | 570 W | 592 W | 88.3% of rated power | ## Against the whole database | Measure | LR7-72HVDF-645M | LR8-66HYD-670M | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #351 | #12 | 14,005 | LR8-66HYD-670M leads by 339 places | | Power density | #356 | #14 | 14,005 | LR8-66HYD-670M leads by 342 places | | Heat behaviour | #511 | #511 | 14,005 | Tied - the same position in the database | | Weight | #5,361 | #3,317 | 14,005 | LR8-66HYD-670M leads by 2,044 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #1,084 | #490 | 14,005 | LR8-66HYD-670M leads by 594 places | ## Questions ### Which panel is better: Longi Solar LR7-72HVDF-645M or Longi Solar LR8-66HYD-670M? According to our database: **Longi Solar LR8-66HYD-670M** has higher module efficiency (**24.80%** vs **23.90%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Longi Solar LR7-72HVDF-645M and Longi Solar LR8-66HYD-670M? **Longi Solar LR7-72HVDF-645M** has a module efficiency of **23.90%**, while **Longi Solar LR8-66HYD-670M** is **24.80%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Longi Solar LR7-72HVDF-645M use vs Longi Solar LR8-66HYD-670M? **Longi Solar LR7-72HVDF-645M** uses **N-type** cells; **Longi Solar LR8-66HYD-670M** uses **Back Contact**. 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 LR7-72HVDF-645M and Longi Solar LR8-66HYD-670M? **Longi Solar LR7-72HVDF-645M** has a **30 years** power warranty; **Longi Solar LR8-66HYD-670M** 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 LR7-72HVDF-645M and Longi Solar LR8-66HYD-670M bifacial panels? Both **Longi Solar LR7-72HVDF-645M** and **Longi Solar LR8-66HYD-670M** 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 LR7-72HVDF-645M vs Longi Solar LR7-72HVDF-665M](https://comparepv.com/compare/longi-lr7-72hvdf-645m/longi-lr7-72hvdf-665m) - 3 differences, the largest is module efficiency - [Longi Solar LR7-72HVDF-645M vs Longi Solar LR7-72HVDF-660M](https://comparepv.com/compare/longi-lr7-72hvdf-645m/longi-lr7-72hvdf-660m) - 3 differences, the largest is module efficiency - [Longi Solar LR7-72HVDF-645M vs Longi Solar LR7-72HVDF-655M](https://comparepv.com/compare/longi-lr7-72hvdf-645m/longi-lr7-72hvdf-655m) - 3 differences, the largest is module efficiency - [Longi Solar LR7-72HVDF-645M vs Longi Solar LR7-72HVDF-650M](https://comparepv.com/compare/longi-lr7-72hvdf-645m/longi-lr7-72hvdf-650m) - One difference: module efficiency - [Longi Solar LR7-72HVDF-645M vs Longi Solar LR7-72HVDF-640M](https://comparepv.com/compare/longi-lr7-72hvdf-645m/longi-lr7-72hvdf-640m) - One difference: module efficiency - [Longi Solar LR8-66HYD-670M vs Longi Solar LR8-66HYD-665M](https://comparepv.com/compare/longi-lr8-66hyd-670m/longi-lr8-66hyd-665m) - One difference: module efficiency --- Source: https://comparepv.com/compare/longi-lr7-72hvdf-645m/longi-lr8-66hyd-670m 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.