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645/LB vs 640/LB 18 of 19 identical Swap Change panels

JA Solar JAM72D42-645/LB vs JA Solar JAM72D42-640/LB

JA Solar JAM72D42-645/LB
JAM72D42-645/LB
645 Wp 23.10 % TOPCon Bifacial
Open panel page Datasheet PDF
VS
JA Solar JAM72D42-640/LB
JAM72D42-640/LB
640 Wp 22.90 % TOPCon Bifacial
Open panel page Datasheet PDF
The verdict

645/LB leads on the differences that matter

The largest is module efficiency: 0.20 pp more efficient. 18 of 19 comparable parameters are identical.

See the one difference
How alike are they
18 of 19 comparable
parameters are identical
identical differs
01

What actually differs

1 of 19 parameters
Parameter 645/LB 640/LB Difference
Module efficiency 23.10 % 22.90 % 0.20 pp more efficient
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 (-0.290 %/°C), so a warmer roof scales both curves by the same factor: the totals fall together and neither panel gains on the other.
645/LB
21,641 kWh
640/LB
21,473 kWh
Lifetime gap
168 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 645/LB 640/LB
Standard test conditions 25 °C 100.0% of rated power 645 W 640 W
Cool, bright day 40 °C 95.7% of rated power 617 W 612 W
Typical summer roof 55 °C 91.3% of rated power 589 W 584 W
Hot roof 70 °C 87.0% of rated power 561 W 556 W
03

Full specification

Parameter 645/LB 640/LB Difference
Power and efficiency
Rated power 645 Wp 640 Wp Effectively the same
Module efficiency 23.10 % 22.90 % +0.20 pp for 645/LB
Power density 230.7 Wp/m² 229.0 Wp/m² Effectively the same
Open-circuit voltage 53.07 V 52.87 V Effectively the same
Voltage at max power 44.49 V 44.29 V Effectively the same
Short-circuit current 15.36 A 15.31 A Effectively the same
Current at max power 14.50 A 14.45 A Effectively the same
Temperature
Temperature coefficient -0.290 %/°C -0.290 %/°C Same
Mechanical
Dimensions 2465x1134x30 mm 2465x1134x30 mm Same
Module area 2.795 m² 2.795 m² Same
Weight 34.6 kg 34.6 kg Same
Weight per kWp 53.6 kg/kWp 54.1 kg/kWp Effectively the same
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.40 %/yr 0.40 %/yr Same
Technology
Cell technology TOPCon TOPCon Same
Cell type Monocrystalline Monocrystalline Same
Cell count 144 144 Same
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#1,570 vs #2,359
645/LB leads by 789 places
Power density
#1,654 vs #2,389
645/LB leads by 735 places
Heat behaviour
#2,165 vs #2,165
Tied - the same position in the database
Weight
#7,650 vs #8,284
645/LB leads by 634 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#1,820 vs #2,090
645/LB leads by 270 places
05

More useful comparisons

Open the full database
Same series, other bin
JA Solar JAM72D42-645/LB vs JA Solar JAM72D42-650/LB
One difference: module efficiency
Same series, other bin
JA Solar JAM72D42-645/LB vs JA Solar JAM72D42-635/LB
3 differences, the largest is module efficiency
Same series, other bin
JA Solar JAM72D42-645/LB vs JA Solar JAM72D42-630/LB
3 differences, the largest is module efficiency
Same series, other bin
JA Solar JAM72D42-645/LB vs JA Solar JAM72D42-625/LB
3 differences, the largest is module efficiency
Same series, other bin
JA Solar JAM72D42-645/LB vs JA Solar JAM72D40-615/LB
6 differences, the largest is rated power
Same series, other bin
JA Solar JAM72D42-645/LB vs JA Solar JAM72D40-610/LB
6 differences, the largest is rated power
06

Written summary

07

Questions about this pairing

Which panel is better: JA Solar JAM72D42-645/LB or JA Solar JAM72D42-640/LB?
According to our database: JA Solar JAM72D42-645/LB has higher module efficiency (23.10% vs 22.90%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of JA Solar JAM72D42-645/LB and JA Solar JAM72D42-640/LB?
JA Solar JAM72D42-645/LB has a module efficiency of 23.10%, while JA Solar JAM72D42-640/LB is 22.90%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does JA Solar JAM72D42-645/LB use vs JA Solar JAM72D42-640/LB?
JA Solar JAM72D42-645/LB uses TOPCon cells; JA Solar JAM72D42-640/LB uses TOPCon. 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 JA Solar JAM72D42-645/LB and JA Solar JAM72D42-640/LB?
JA Solar JAM72D42-645/LB has a 30 years power warranty; JA Solar JAM72D42-640/LB 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 JA Solar JAM72D42-645/LB and JA Solar JAM72D42-640/LB bifacial panels?
Both JA Solar JAM72D42-645/LB and JA Solar JAM72D42-640/LB 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 393 JA 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.