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LR8-66HVD-665M vs LR7-72HVD-665M 13 of 19 identical Swap Change panels

Longi Solar LR8-66HVD-665M vs Longi Solar LR7-72HVD-665M

Longi Solar LR8-66HVD-665M
LR8-66HVD-665M
665 Wp 24.62 % Back Contact Bifacial
Open panel page Datasheet PDF
VS
Longi Solar LR7-72HVD-665M
LR7-72HVD-665M
665 Wp 24.60 % N-type Bifacial
Open panel page Datasheet PDF
The verdict

6 differences, none of them an advantage

The largest is open-circuit voltage: 4.50 V apart. 13 of 19 comparable parameters are identical.

See all 6 differences
How alike are they
13 of 19 comparable
parameters are identical
identical differs
01

What actually differs

6 of 19 parameters
Parameter LR8-66HVD-665M LR7-72HVD-665M Difference
Open-circuit voltage 50.02 V 54.52 V 4.50 V apart
Short-circuit current 16.78 A 15.35 A 1.43 A apart
Cell technology Back Contact N-type Back Contact vs N-type
Cell count 132 144 12 cells apart
Voltage at max power 41.28 V 45.17 V 3.89 V apart
Current at max power 16.11 A 14.72 A 1.39 A apart
02

What it means on a roof

Thirty years of production
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.
LR8-66HVD-665M
22,486 kWh
LR7-72HVD-665M
22,486 kWh
Lifetime gap
No difference
Output when it is hot
Rated power carried across the range a module actually sees
Scenario LR8-66HVD-665M LR7-72HVD-665M
Standard test conditions 25 °C 100.0% of rated power 665 W 665 W
Cool, bright day 40 °C 96.1% of rated power 639 W 639 W
Typical summer roof 55 °C 92.2% of rated power 613 W 613 W
Hot roof 70 °C 88.3% of rated power 587 W 587 W
03

Full specification

Parameter LR8-66HVD-665M LR7-72HVD-665M Difference
Power and efficiency
Rated power 665 Wp 665 Wp Same
Module efficiency 24.62 % 24.60 % Effectively the same
Power density 246.2 Wp/m² 246.2 Wp/m² Same
Open-circuit voltage 50.02 V 54.52 V 4.50 V apart
Voltage at max power 41.28 V 45.17 V 3.89 V apart
Short-circuit current 16.78 A 15.35 A 1.43 A apart
Current at max power 16.11 A 14.72 A 1.39 A apart
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 50.4 kg/kWp 50.4 kg/kWp Same
Warranty and degradation
Product warranty 15 yrs 15 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.35 %/yr 0.35 %/yr Same
Technology
Cell technology Back Contact N-type Back Contact vs N-type
Cell type Monocrystalline Monocrystalline Same
Cell count 132 144 12 cells apart
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#42 vs #51
LR8-66HVD-665M leads by 9 places
Power density
#42 vs #42
Tied - the same position in the database
Heat behaviour
#511 vs #511
Tied - the same position in the database
Weight
#3,742 vs #3,742
Tied - the same position in the database
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#397 vs #414
LR8-66HVD-665M leads by 17 places
05

More useful comparisons

Open the full database
Same series, other bin
Longi Solar LR8-66HVD-665M vs Longi Solar LR8-66HVD-660M
The same specification on paper
Same series, other bin
Longi Solar LR8-66HVD-665M vs Longi Solar LR8-66HVD-655M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR8-66HVD-665M vs Longi Solar LR8-66HVD-650M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR8-66HVD-665M vs Longi Solar LR8-66HVD-645M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR8-66HVD-665M vs Longi Solar LR8-66HVD-640M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR7-72HVD-665M vs Longi Solar LR7-72HVD-660M
One difference: module efficiency
06

Written summary

07

Questions about this pairing

Which panel is better: Longi Solar LR8-66HVD-665M or Longi Solar LR7-72HVD-665M?
According to our database: Longi Solar LR8-66HVD-665M has higher module efficiency (24.62% vs 24.60%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Longi Solar LR8-66HVD-665M and Longi Solar LR7-72HVD-665M?
Longi Solar LR8-66HVD-665M has a module efficiency of 24.62%, while Longi Solar LR7-72HVD-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 LR8-66HVD-665M use vs Longi Solar LR7-72HVD-665M?
Longi Solar LR8-66HVD-665M uses Back Contact cells; Longi Solar LR7-72HVD-665M 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 LR8-66HVD-665M and Longi Solar LR7-72HVD-665M?
Longi Solar LR8-66HVD-665M has a 30 years power warranty; Longi Solar LR7-72HVD-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 LR8-66HVD-665M and Longi Solar LR7-72HVD-665M bifacial panels?
Both Longi Solar LR8-66HVD-665M and Longi Solar LR7-72HVD-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.