Longi Solar LR7-54HJD-510M vs Longi Solar LR8-66HVD-645M
VS
The verdict
LR7-54HJD-510M leads on the differences that matter
The largest is module efficiency: 1.12 pp more efficient. 5 of 19 comparable parameters are identical.
See all 14 differencesHow alike are they
5
of 19 comparable
parameters are identical
parameters are identical
identical
differs
01
14 of 19 parameters
What actually differs
Parameter
LR7-54HJD-510M
LR8-66HVD-645M
Difference
Module efficiency
25.00 %
23.88 %
1.12 pp more efficient
Rated power
510 Wp
645 Wp
135 W more power
Power density
249.9 Wp/m²
238.8 Wp/m²
11.1 Wp/m² higher
Weight
23.5 kg
33.5 kg
10.0 kg lighter
Product warranty
30 yrs
15 yrs
15 yrs longer
Temperature coefficient
-0.240 %/°C
-0.260 %/°C
0.020 %/°C better in heat
Weight per kWp
46.1 kg/kWp
51.9 kg/kWp
5.9 kg/kWp lighter
Open-circuit voltage
41.55 V
49.62 V
8.07 V apart
Module area
2.041 m²
2.701 m²
0.660 m² apart
Voltage at max power
34.37 V
40.88 V
6.51 V apart
Cell count
108
132
24 cells apart
Short-circuit current
15.52 A
16.46 A
0.94 A apart
Dimensions
1800x1134x30 mm
2382x1134x30 mm
1800x1134x30 mm vs 2382x1134x30 mm
Current at max power
14.84 A
15.78 A
0.94 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
LR7-54HJD-510M
17,245 kWh
LR8-66HVD-645M
21,809 kWh
Lifetime gap
4,564 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario
LR7-54HJD-510M
LR8-66HVD-645M
Standard test conditions
25 °C
100.0% of rated power
510 W
645 W
Cool, bright day
40 °C
96.1% of rated power
492 W
620 W
Typical summer roof
55 °C
92.2% of rated power
473 W
595 W
Hot roof
70 °C
88.3% of rated power
455 W
570 W
03
Full specification
Parameter
LR7-54HJD-510M
LR8-66HVD-645M
Difference
Power and efficiency
Rated power
510 Wp
645 Wp
+135 W for LR8-66HVD-645M
Module efficiency
25.00 %
23.88 %
+1.12 pp for LR7-54HJD-510M
Power density
249.9 Wp/m²
238.8 Wp/m²
+11.1 Wp/m² for LR7-54HJD-510M
Open-circuit voltage
41.55 V
49.62 V
8.07 V apart
Voltage at max power
34.37 V
40.88 V
6.51 V apart
Short-circuit current
15.52 A
16.46 A
0.94 A apart
Current at max power
14.84 A
15.78 A
0.94 A apart
Temperature
Temperature coefficient
-0.240 %/°C
-0.260 %/°C
+0.020 %/°C for LR7-54HJD-510M
Mechanical
Dimensions
1800x1134x30 mm
2382x1134x30 mm
1800x1134x30 mm vs 2382x1134x30 mm
Module area
2.041 m²
2.701 m²
0.660 m² apart
Weight
23.5 kg
33.5 kg
-10.0 kg for LR7-54HJD-510M
Weight per kWp
46.1 kg/kWp
51.9 kg/kWp
-5.9 kg/kWp for LR7-54HJD-510M
Warranty and degradation
Product warranty
30 yrs
15 yrs
+15 yrs for LR7-54HJD-510M
Performance warranty
30 yrs
30 yrs
Same
Annual degradation
0.35 %/yr
0.35 %/yr
Same
Technology
Cell technology
Back Contact
Back Contact
Same
Cell type
Monocrystalline
Monocrystalline
Same
Cell count
108
132
24 cells apart
Bifacial
Yes
Yes
Same
04
14,005 panels
Against the whole database
Efficiency
#4
vs
#394
LR7-54HJD-510M leads by 390 places
Power density
#7
vs
#356
LR7-54HJD-510M leads by 349 places
Heat behaviour
#13
vs
#511
LR7-54HJD-510M leads by 498 places
Weight
#979
vs
#5,361
LR7-54HJD-510M leads by 4,382 places
Warranty
#21
vs
#21
Tied - the same position in the database
Overall
#1,144
vs
#1,084
LR8-66HVD-645M leads by 60 places
05
Open the full database
More useful comparisons
Same series, other bin
Longi Solar LR7-54HJD-510M vs Longi Solar LR7-54HJD-505M
One difference: module efficiency
Same series, other bin
Longi Solar LR7-54HJD-510M vs Longi Solar LR7-54HJD-500M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR7-54HJD-510M vs Longi Solar LR7-54HJD-495M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR8-66HVD-645M vs Longi Solar LR8-66HVD-665M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR8-66HVD-645M vs Longi Solar LR8-66HVD-660M
3 differences, the largest is module efficiency
Same series, other bin
Longi Solar LR8-66HVD-645M vs Longi Solar LR8-66HVD-655M
3 differences, the largest is module efficiency
06
Written summary
Checking cache...
07
Questions about this pairing
Which panel is better: Longi Solar LR7-54HJD-510M or Longi Solar LR8-66HVD-645M?
According to our database: Longi Solar LR7-54HJD-510M has higher module efficiency (25.00% vs 23.88%); Longi Solar LR7-54HJD-510M tolerates heat better (temp coeff -0.240%/°C vs -0.260%/°C). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Longi Solar LR7-54HJD-510M and Longi Solar LR8-66HVD-645M?
Longi Solar LR7-54HJD-510M has a module efficiency of 25.00%, while Longi Solar LR8-66HVD-645M is 23.88%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Longi Solar LR7-54HJD-510M use vs Longi Solar LR8-66HVD-645M?
Longi Solar LR7-54HJD-510M uses Back Contact cells; Longi Solar LR8-66HVD-645M 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 LR7-54HJD-510M and Longi Solar LR8-66HVD-645M?
Longi Solar LR7-54HJD-510M has a 30 years power warranty; Longi Solar LR8-66HVD-645M 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 LR7-54HJD-510M and Longi Solar LR8-66HVD-645M bifacial panels?
Both Longi Solar LR7-54HJD-510M and Longi Solar LR8-66HVD-645M 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.