--- title: "Longi Solar LR5-54HIB-405M vs Longi Solar LR8-66HYD-665M - Solar Panel Comparison | ComparePV" description: "Compare Longi Solar LR5-54HIB-405M vs Longi Solar LR8-66HYD-665M side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/longi-lr5-54hib-405m/longi-lr8-66hyd-665m" image: "https://comparepv.com/og/compare/panels/longi-lr5-54hib-405m/longi-lr8-66hyd-665m.png" updated: 2026-09-11 --- # Longi Solar LR5-54HIB-405M vs Longi Solar LR8-66HYD-665M LR8-66HYD-665M leads on the differences that matter The largest is module efficiency: 3.90 pp more efficient. 2 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 LR5-54HIB-405M](https://comparepv.com/panel/longi-lr5-54hib-405m) | [Longi Solar LR8-66HYD-665M](https://comparepv.com/panel/longi-lr8-66hyd-665m) | | Manufacturer | Longi Solar | Longi Solar | | Power | 405 Wp | 665 Wp | | Efficiency | 20.70 % | 24.60 % | | Technology | PERC | Back Contact | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | LR5-54HIB-405M | LR8-66HYD-665M | Difference | | --- | --- | --- | --- | | Module efficiency | 20.70 % | 24.60 % | +3.90 pp for LR8-66HYD-665M | | Temperature coefficient | -0.340 %/°C | -0.260 %/°C | +0.080 %/°C for LR8-66HYD-665M | | Rated power | 405 Wp | 665 Wp | +260 W for LR8-66HYD-665M | | Power density | 207.4 Wp/m² | 246.2 Wp/m² | +38.8 Wp/m² for LR8-66HYD-665M | | Performance warranty | 25 yrs | 30 yrs | +5 yrs for LR8-66HYD-665M | | Weight | 21.5 kg | 33.5 kg | -12.0 kg for LR5-54HIB-405M | | Open-circuit voltage | 37.15 V | 50.02 V | 12.87 V apart | | Short-circuit current | 13.78 A | 16.78 A | 3.00 A apart | | Module area | 1.953 m² | 2.701 m² | 0.748 m² apart | | Cell technology | PERC | Back Contact | PERC vs Back Contact | | Weight per kWp | 53.1 kg/kWp | 50.4 kg/kWp | -2.7 kg/kWp for LR8-66HYD-665M | | Voltage at max power | 31.18 V | 41.28 V | 10.10 V apart | | Current at max power | 12.99 A | 16.11 A | 3.12 A apart | | Cell count | 108 | 132 | 24 cells apart | | Bifacial | No | Yes | No vs Yes | | Dimensions | 1722x1134x30 mm | 2382x1134x30 mm | 1722x1134x30 mm vs 2382x1134x30 mm | ## Every compared parameter | Parameter | LR5-54HIB-405M | LR8-66HYD-665M | | --- | --- | --- | | Rated power | 405 Wp | 665 Wp | | Module efficiency | 20.70 % | 24.60 % | | Power density | 207.4 Wp/m² | 246.2 Wp/m² | | Open-circuit voltage | 37.15 V | 50.02 V | | Voltage at max power | 31.18 V | 41.28 V | | Short-circuit current | 13.78 A | 16.78 A | | Current at max power | 12.99 A | 16.11 A | | Temperature coefficient | -0.340 %/°C | -0.260 %/°C | | Dimensions | 1722x1134x30 mm | 2382x1134x30 mm | | Module area | 1.953 m² | 2.701 m² | | Weight | 21.5 kg | 33.5 kg | | Weight per kWp | 53.1 kg/kWp | 50.4 kg/kWp | | Product warranty | 12 yrs | 12 yrs | | Performance warranty | 25 yrs | 30 yrs | | Annual degradation | 0.55 %/yr | - | | Cell technology | PERC | Back Contact | | Cell type | Monocrystalline | Monocrystalline | | Cell count | 108 | 132 | | Bifacial | No | 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 - **Cumulative output, LR5-54HIB-405M:** 13,589 kWh - **Cumulative output, LR8-66HYD-665M:** 22,312 kWh - **Gap:** 8,723 kWh ## Output when hot | Condition | Cell temperature | LR5-54HIB-405M | LR8-66HYD-665M | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 405 W | 665 W | 100.0% of rated power | | Cool, bright day | 40 °C | 384 W | 639 W | 94.9% of rated power | | Typical summer roof | 55 °C | 364 W | 613 W | 89.8% of rated power | | Hot roof | 70 °C | 343 W | 587 W | 84.7% of rated power | ## Against the whole database | Measure | LR5-54HIB-405M | LR8-66HYD-665M | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #10,842 | #58 | 14,129 | LR8-66HYD-665M leads by 10,784 places | | Power density | #10,702 | #47 | 14,129 | LR8-66HYD-665M leads by 10,655 places | | Heat behaviour | #8,846 | #515 | 14,129 | LR8-66HYD-665M leads by 8,331 places | | Weight | #6,908 | #3,759 | 14,129 | LR8-66HYD-665M leads by 3,149 places | | Warranty | #9,912 | #21 | 14,129 | LR8-66HYD-665M leads by 9,891 places | | Overall | #12,029 | #654 | 14,129 | LR8-66HYD-665M leads by 11,375 places | ## Questions ### Which panel is better: Longi Solar LR5-54HIB-405M or Longi Solar LR8-66HYD-665M? According to our database: **Longi Solar LR8-66HYD-665M** has higher module efficiency (**24.60%** vs **20.70%**); **Longi Solar LR8-66HYD-665M** tolerates heat better (temp coeff **-0.260%/°C** vs **-0.340%/°C**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Longi Solar LR5-54HIB-405M and Longi Solar LR8-66HYD-665M? **Longi Solar LR5-54HIB-405M** has a module efficiency of **20.70%**, while **Longi Solar LR8-66HYD-665M** is **24.60%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Longi Solar LR5-54HIB-405M use vs Longi Solar LR8-66HYD-665M? **Longi Solar LR5-54HIB-405M** uses **PERC** cells; **Longi Solar LR8-66HYD-665M** 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 LR5-54HIB-405M and Longi Solar LR8-66HYD-665M? **Longi Solar LR5-54HIB-405M** has a **25 years** power warranty; **Longi Solar LR8-66HYD-665M** 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 LR5-54HIB-405M and Longi Solar LR8-66HYD-665M bifacial panels? **Longi Solar LR8-66HYD-665M** is bifacial (captures light from both faces); **Longi Solar LR5-54HIB-405M** is monofacial. Bifacial panels work best on ground mounts or raised structures with a light-coloured surface underneath. ## Related comparisons - [Longi Solar LR5-54HIB-405M vs Longi Solar LR5-72HPH-565M](https://comparepv.com/compare/longi-lr5-54hib-405m/longi-lr5-72hph-565m) - 10 differences, the largest is module efficiency - [Longi Solar LR5-54HIB-405M vs Longi Solar LR5-72HPH-560M](https://comparepv.com/compare/longi-lr5-54hib-405m/longi-lr5-72hph-560m) - 10 differences, the largest is module efficiency - [Longi Solar LR5-54HIB-405M vs Longi Solar LR5-72HPH-555M](https://comparepv.com/compare/longi-lr5-54hib-405m/longi-lr5-72hph-555m) - 10 differences, the largest is module efficiency - [Longi Solar LR5-54HIB-405M vs Longi Solar LR5-72HPH-550M](https://comparepv.com/compare/longi-lr5-54hib-405m/longi-lr5-72hph-550m) - 10 differences, the largest is rated power - [Longi Solar LR5-54HIB-405M vs Longi Solar LR5-72HPH-545M](https://comparepv.com/compare/longi-lr5-54hib-405m/longi-lr5-72hph-545m) - 10 differences, the largest is rated power - [Longi Solar LR5-54HIB-405M vs Longi Solar LR5-66HPH-515M](https://comparepv.com/compare/longi-lr5-54hib-405m/longi-green-energy-technology-co-ltd-lr5-66hph-515m) - 10 differences, the largest is module efficiency --- Source: https://comparepv.com/compare/longi-lr5-54hib-405m/longi-lr8-66hyd-665m 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.