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640/LB vs 635/LB 18 of 19 identical Swap Change panels

JA Solar JAM72D42-640/LB vs JA Solar JAM72D42-635/LB

JA Solar JAM72D42-640/LB
JAM72D42-640/LB
640 Wp 22.90 % TOPCon Bifacial
Open panel page Datasheet PDF
VS
JA Solar JAM72D42-635/LB
JAM72D42-635/LB
635 Wp 22.70 % TOPCon Bifacial
Open panel page Datasheet PDF
The verdict

640/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 640/LB 635/LB Difference
Module efficiency 22.90 % 22.70 % 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.
640/LB
21,473 kWh
635/LB
21,306 kWh
Lifetime gap
167 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 640/LB 635/LB
Standard test conditions 25 °C 100.0% of rated power 640 W 635 W
Cool, bright day 40 °C 95.7% of rated power 612 W 607 W
Typical summer roof 55 °C 91.3% of rated power 584 W 580 W
Hot roof 70 °C 87.0% of rated power 556 W 552 W
03

Full specification

Parameter 640/LB 635/LB Difference
Power and efficiency
Rated power 640 Wp 635 Wp Effectively the same
Module efficiency 22.90 % 22.70 % +0.20 pp for 640/LB
Power density 229.0 Wp/m² 227.2 Wp/m² Effectively the same
Open-circuit voltage 52.87 V 52.67 V Effectively the same
Voltage at max power 44.29 V 44.10 V Effectively the same
Short-circuit current 15.31 A 15.26 A Effectively the same
Current at max power 14.45 A 14.40 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 54.1 kg/kWp 54.5 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
#2,359 vs #3,307
640/LB leads by 948 places
Power density
#2,389 vs #3,252
640/LB leads by 863 places
Heat behaviour
#2,165 vs #2,165
Tied - the same position in the database
Weight
#8,284 vs #8,832
640/LB leads by 548 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#2,090 vs #2,396
640/LB leads by 306 places
05

More useful comparisons

Open the full database
Same series, other bin
JA Solar JAM72D42-640/LB vs JA Solar JAM72D42-650/LB
3 differences, the largest is module efficiency
Same series, other bin
JA Solar JAM72D42-640/LB vs JA Solar JAM72D42-645/LB
One difference: module efficiency
Same series, other bin
JA Solar JAM72D42-640/LB vs JA Solar JAM72D42-630/LB
3 differences, the largest is module efficiency
Same series, other bin
JA Solar JAM72D42-640/LB vs JA Solar JAM72D42-625/LB
3 differences, the largest is module efficiency
Same series, other bin
JA Solar JAM72D42-640/LB vs JA Solar JAM72D40-615/LB
8 differences, the largest is rated power
Same series, other bin
JA Solar JAM72D42-640/LB vs JA Solar JAM72D40-610/LB
7 differences, the largest is rated power
06

Written summary

07

Questions about this pairing

Which panel is better: JA Solar JAM72D42-640/LB or JA Solar JAM72D42-635/LB?
According to our database: JA Solar JAM72D42-640/LB has higher module efficiency (22.90% vs 22.70%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of JA Solar JAM72D42-640/LB and JA Solar JAM72D42-635/LB?
JA Solar JAM72D42-640/LB has a module efficiency of 22.90%, while JA Solar JAM72D42-635/LB is 22.70%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does JA Solar JAM72D42-640/LB use vs JA Solar JAM72D42-635/LB?
JA Solar JAM72D42-640/LB uses TOPCon cells; JA Solar JAM72D42-635/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 JAM72D42-640/LB and JA Solar JAM72D42-635/LB?
JA Solar JAM72D42-640/LB has a 30 years power warranty; JA Solar JAM72D42-635/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 JAM72D42-640/LB and JA Solar JAM72D42-635/LB bifacial panels?
Both JA Solar JAM72D42-640/LB and JA Solar JAM72D42-635/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 389 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.