Skip to main content
LR8-66HYD-665M vs LR5-54HIB-405M 2 of 18 identical Swap Change panels

Longi Solar LR8-66HYD-665M vs Longi Solar LR5-54HIB-405M

Longi Solar LR8-66HYD-665M
LR8-66HYD-665M
665 Wp 24.60 % Back Contact Bifacial Incomplete
Open panel page Datasheet PDF
VS
Longi Solar LR5-54HIB-405M
LR5-54HIB-405M
405 Wp 20.70 % PERC
Open panel page Datasheet PDF
The verdict

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.

See all 16 differences
How alike are they
2 of 18 comparable
parameters are identical
identical differs not published
01

What actually differs

16 of 18 parameters
Parameter LR8-66HYD-665M LR5-54HIB-405M Difference
Module efficiency 24.60 % 20.70 % 3.90 pp more efficient
Temperature coefficient -0.260 %/°C -0.340 %/°C 0.080 %/°C better in heat
Rated power 665 Wp 405 Wp 260 W more power
Power density 246.2 Wp/m² 207.4 Wp/m² 38.8 Wp/m² higher
Performance warranty 30 yrs 25 yrs 5 yrs longer
Weight 33.5 kg 21.5 kg 12.0 kg lighter
Open-circuit voltage 50.02 V 37.15 V 12.87 V apart
Short-circuit current 16.78 A 13.78 A 3.00 A apart
Module area 2.701 m² 1.953 m² 0.748 m² apart
Cell technology Back Contact PERC Back Contact vs PERC
Weight per kWp 50.4 kg/kWp 53.1 kg/kWp 2.7 kg/kWp lighter
Voltage at max power 41.28 V 31.18 V 10.10 V apart
Current at max power 16.11 A 12.99 A 3.12 A apart
Cell count 132 108 24 cells apart
Bifacial Yes No Yes vs No
Dimensions 2382x1134x30 mm 1722x1134x30 mm 2382x1134x30 mm vs 1722x1134x30 mm
02

What it means on a roof

Thirty years of production
A 1.0% first-year loss then 0.40% a year, assumed for both panels, at 1,200 kWh/kWp a year
LR8-66HYD-665M
22,312 kWh
LR5-54HIB-405M
13,589 kWh
Lifetime gap
8,723 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario LR8-66HYD-665M LR5-54HIB-405M
Standard test conditions 25 °C 100.0% of rated power 665 W 405 W
Cool, bright day 40 °C 94.9% of rated power 639 W 384 W
Typical summer roof 55 °C 89.8% of rated power 613 W 364 W
Hot roof 70 °C 84.7% of rated power 587 W 343 W
03

Full specification

Parameter LR8-66HYD-665M LR5-54HIB-405M Difference
Power and efficiency
Rated power 665 Wp 405 Wp +260 W for LR8-66HYD-665M
Module efficiency 24.60 % 20.70 % +3.90 pp for LR8-66HYD-665M
Power density 246.2 Wp/m² 207.4 Wp/m² +38.8 Wp/m² for LR8-66HYD-665M
Open-circuit voltage 50.02 V 37.15 V 12.87 V apart
Voltage at max power 41.28 V 31.18 V 10.10 V apart
Short-circuit current 16.78 A 13.78 A 3.00 A apart
Current at max power 16.11 A 12.99 A 3.12 A apart
Temperature
Temperature coefficient -0.260 %/°C -0.340 %/°C +0.080 %/°C for LR8-66HYD-665M
Mechanical
Dimensions 2382x1134x30 mm 1722x1134x30 mm 2382x1134x30 mm vs 1722x1134x30 mm
Module area 2.701 m² 1.953 m² 0.748 m² apart
Weight 33.5 kg 21.5 kg -12.0 kg for LR5-54HIB-405M
Weight per kWp 50.4 kg/kWp 53.1 kg/kWp -2.7 kg/kWp for LR8-66HYD-665M
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 30 yrs 25 yrs +5 yrs for LR8-66HYD-665M
Annual degradation - 0.55 %/yr Not published by Longi Solar
Technology
Cell technology Back Contact PERC Back Contact vs PERC
Cell type Monocrystalline Monocrystalline Same
Cell count 132 108 24 cells apart
Bifacial Yes No Yes vs No
04

Against the whole database

14,129 panels
Efficiency
#58 vs #10,842
LR8-66HYD-665M leads by 10,784 places
Power density
#47 vs #10,702
LR8-66HYD-665M leads by 10,655 places
Heat behaviour
#515 vs #8,846
LR8-66HYD-665M leads by 8,331 places
Weight
#3,759 vs #6,908
LR8-66HYD-665M leads by 3,149 places
Warranty
#21 vs #9,912
LR8-66HYD-665M leads by 9,891 places
Overall
#654 vs #12,029
LR8-66HYD-665M leads by 11,375 places
05

More useful comparisons

Open the full database
Same series, other bin
Longi Solar LR8-66HYD-665M vs Longi Solar LR8-66HYD-670M
One difference: module efficiency
Same series, other bin
Longi Solar LR8-66HYD-665M vs Longi Solar LR8-66HYD-660M
One difference: module efficiency
Same series, other bin
Longi Solar LR8-66HYD-665M vs Longi Solar LR7-72HYD-660M
7 differences, the largest is open-circuit voltage
Same series, other bin
Longi Solar LR8-66HYD-665M vs Longi Solar LR8-66HYD-655M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR8-66HYD-665M vs Longi Solar LR7-72HYD-655M
9 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR8-66HYD-665M vs Longi Solar LR8-66HYD-650M
3 differences, the largest is module efficiency
06

Written summary

07

Questions about this pairing

Which panel is better: Longi Solar LR8-66HYD-665M or Longi Solar LR5-54HIB-405M?
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 LR8-66HYD-665M and Longi Solar LR5-54HIB-405M?
Longi Solar LR8-66HYD-665M has a module efficiency of 24.60%, while Longi Solar LR5-54HIB-405M is 20.70%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Longi Solar LR8-66HYD-665M use vs Longi Solar LR5-54HIB-405M?
Longi Solar LR8-66HYD-665M uses Back Contact cells; Longi Solar LR5-54HIB-405M 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 Longi Solar LR8-66HYD-665M and Longi Solar LR5-54HIB-405M?
Longi Solar LR8-66HYD-665M has a 30 years power warranty; Longi Solar LR5-54HIB-405M has a 25 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 LR8-66HYD-665M and Longi Solar LR5-54HIB-405M 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.

Shop prices: See 156 Longi Solar offers

Every figure here is from the manufacturers' own datasheets - a dash means the value is not published, never an estimate. The thirty-year projection and the temperature scenarios are calculations from those figures, and each states its assumption above.