Skip to main content
650M vs 665M 15 of 18 identical Swap Change panels

Longi Solar LR8-66HYD-650M vs Longi Solar LR8-66HYD-665M

Longi Solar LR8-66HYD-650M
LR8-66HYD-650M
650 Wp 24.10 % Back Contact Bifacial
Open panel page Datasheet PDF
VS
Longi Solar LR8-66HYD-665M
LR8-66HYD-665M
665 Wp 24.60 % Back Contact Bifacial Incomplete
Open panel page Datasheet PDF
The verdict

665M leads on the differences that matter

The largest is module efficiency: 0.50 pp more efficient. 15 of 18 comparable parameters are identical, with 1 more left out because at least one datasheet does not publish it.

See all 3 differences
How alike are they
15 of 18 comparable
parameters are identical
identical differs not published
01

What actually differs

3 of 18 parameters
Parameter 650M 665M Difference
Module efficiency 24.10 % 24.60 % 0.50 pp more efficient
Power density 240.6 Wp/m² 246.2 Wp/m² 5.6 Wp/m² higher
Rated power 650 Wp 665 Wp 15 W more power
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
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.
650M
21,809 kWh
665M
22,312 kWh
Lifetime gap
503 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 650M 665M
Standard test conditions 25 °C 100.0% of rated power 650 W 665 W
Cool, bright day 40 °C 96.1% of rated power 625 W 639 W
Typical summer roof 55 °C 92.2% of rated power 599 W 613 W
Hot roof 70 °C 88.3% of rated power 574 W 587 W
03

Full specification

Parameter 650M 665M Difference
Power and efficiency
Rated power 650 Wp 665 Wp +15 W for 665M
Module efficiency 24.10 % 24.60 % +0.50 pp for 665M
Power density 240.6 Wp/m² 246.2 Wp/m² +5.6 Wp/m² for 665M
Open-circuit voltage 50.01 V 50.02 V Effectively the same
Voltage at max power 41.20 V 41.28 V Effectively the same
Short-circuit current 16.49 A 16.78 A Effectively the same
Current at max power 15.78 A 16.11 A Effectively the same
Temperature
Temperature coefficient -0.260 %/°C -0.260 %/°C Same
Mechanical
Dimensions 2382x1134x30 mm 2382x1134x30 mm Same
Module area 2.701 m² 2.701 m² Same
Weight 33.5 kg 33.5 kg Same
Weight per kWp 51.5 kg/kWp 50.4 kg/kWp Effectively the same
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.35 %/yr - Not published by Longi Solar
Technology
Cell technology Back Contact Back Contact Same
Cell type Monocrystalline Monocrystalline Same
Cell count 132 132 Same
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#219 vs #51
665M leads by 168 places
Power density
#233 vs #42
665M leads by 191 places
Heat behaviour
#511 vs #511
Tied - the same position in the database
Weight
#4,914 vs #3,742
665M leads by 1,172 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#1,158 vs #643
665M leads by 515 places
05

More useful comparisons

Open the full database
Same series, other bin
Longi Solar LR8-66HYD-650M vs Longi Solar LR8-66HYD-670M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR8-66HYD-650M vs Longi Solar LR8-66HYD-660M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR8-66HYD-650M vs Longi Solar LR7-72HYD-660M
9 differences, the largest is open-circuit voltage
Same series, other bin
Longi Solar LR8-66HYD-650M vs Longi Solar LR8-66HYD-655M
The same specification on paper
Same series, other bin
Longi Solar LR8-66HYD-650M vs Longi Solar LR7-72HYD-655M
6 differences, the largest is open-circuit voltage
Same series, other bin
Longi Solar LR8-66HYD-650M vs Longi Solar LR7-72HYD-650M
6 differences, the largest is open-circuit voltage
06

Written summary

07

Questions about this pairing

Which panel is better: Longi Solar LR8-66HYD-650M or Longi Solar LR8-66HYD-665M?
According to our database: Longi Solar LR8-66HYD-665M has higher module efficiency (24.60% vs 24.10%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Longi Solar LR8-66HYD-650M and Longi Solar LR8-66HYD-665M?
Longi Solar LR8-66HYD-650M has a module efficiency of 24.10%, 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 LR8-66HYD-650M use vs Longi Solar LR8-66HYD-665M?
Longi Solar LR8-66HYD-650M uses Back Contact 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 LR8-66HYD-650M and Longi Solar LR8-66HYD-665M?
Longi Solar LR8-66HYD-650M has a 30 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 LR8-66HYD-650M and Longi Solar LR8-66HYD-665M bifacial panels?
Both Longi Solar LR8-66HYD-650M and Longi Solar LR8-66HYD-665M 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.

Shop prices: See 174 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.