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620 vs 640 14 of 19 identical Swap Change panels

Q-Cells Q.TRON XL-G2.3 / BFG 620 vs Q-Cells Q.TRON XL-G2.3 / BFG 640

Q-Cells Q.TRON XL-G2.3 / BFG 620
Q.TRON XL-G2.3 / BFG 620
620 Wp 22.20 % N-type Bifacial
Open panel page Datasheet PDF
VS
Q-Cells Q.TRON XL-G2.3 / BFG 640
Q.TRON XL-G2.3 / BFG 640
640 Wp 22.90 % N-type Bifacial
Open panel page Datasheet PDF
The verdict

640 leads on the differences that matter

The largest is module efficiency: 0.70 pp more efficient. 14 of 19 comparable parameters are identical.

See all 5 differences
How alike are they
14 of 19 comparable
parameters are identical
identical differs
01

What actually differs

5 of 19 parameters
Parameter 620 640 Difference
Module efficiency 22.20 % 22.90 % 0.70 pp more efficient
Power density 222.1 Wp/m² 229.2 Wp/m² 7.2 Wp/m² higher
Rated power 620 Wp 640 Wp 20 W more power
Temperature coefficient -0.300 %/°C -0.290 %/°C 0.010 %/°C better in heat
Open-circuit voltage 56.67 V 57.79 V 1.12 V 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
620
20,917 kWh
640
21,592 kWh
Lifetime gap
675 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 620 640
Standard test conditions 25 °C 100.0% of rated power 620 W 640 W
Cool, bright day 40 °C 95.5% of rated power 592 W 612 W
Typical summer roof 55 °C 91.0% of rated power 564 W 584 W
Hot roof 70 °C 86.5% of rated power 536 W 556 W
03

Full specification

Parameter 620 640 Difference
Power and efficiency
Rated power 620 Wp 640 Wp +20 W for 640
Module efficiency 22.20 % 22.90 % +0.70 pp for 640
Power density 222.1 Wp/m² 229.2 Wp/m² +7.2 Wp/m² for 640
Open-circuit voltage 56.67 V 57.79 V 1.12 V apart
Voltage at max power 47.50 V 48.28 V Effectively the same
Short-circuit current 13.76 A 13.99 A Effectively the same
Current at max power 13.05 A 13.26 A Effectively the same
Temperature
Temperature coefficient -0.300 %/°C -0.290 %/°C +0.010 %/°C for 640
Mechanical
Dimensions 2462x1134x35 mm 2462x1134x35 mm Same
Module area 2.792 m² 2.792 m² Same
Weight 35.4 kg 35.4 kg Same
Weight per kWp 57.1 kg/kWp 55.3 kg/kWp Effectively the same
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.33 %/yr 0.33 %/yr Same
Technology
Cell technology N-type N-type Same
Cell type Monocrystalline Monocrystalline Same
Cell count 156 156 Same
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#5,817 vs #2,359
640 leads by 3,458 places
Power density
#5,847 vs #2,368
640 leads by 3,479 places
Heat behaviour
#6,093 vs #2,165
640 leads by 3,928 places
Weight
#11,047 vs #9,773
640 leads by 1,274 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#3,468 vs #2,116
640 leads by 1,352 places
05

More useful comparisons

Open the full database
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 620 vs Q-Cells Q.TRON XL-G2.3 / BFG 645
6 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 620 vs Q-Cells Q.TRON XL-G2.3 / BFG 635
3 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 620 vs Q-Cells Q.TRON XL-G2.3 / BFG 630
3 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 620 vs Q-Cells Q.TRON XL-G2.3 / BFG 625
One difference: module efficiency
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 620 vs Q-Cells Q.TRON XL-G2.3 / BFG 615
One difference: module efficiency
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 620 vs Q-Cells Q.TRON XL-G2.3 / BFG 610
3 differences, the largest is module efficiency
06

Written summary

07

Questions about this pairing

Which panel is better: Q-Cells Q.TRON XL-G2.3 / BFG 620 or Q-Cells Q.TRON XL-G2.3 / BFG 640?
According to our database: Q-Cells Q.TRON XL-G2.3 / BFG 640 has higher module efficiency (22.90% vs 22.20%); Q-Cells Q.TRON XL-G2.3 / BFG 640 tolerates heat better (temp coeff -0.290%/°C vs -0.300%/°C). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Q-Cells Q.TRON XL-G2.3 / BFG 620 and Q-Cells Q.TRON XL-G2.3 / BFG 640?
Q-Cells Q.TRON XL-G2.3 / BFG 620 has a module efficiency of 22.20%, while Q-Cells Q.TRON XL-G2.3 / BFG 640 is 22.90%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Q-Cells Q.TRON XL-G2.3 / BFG 620 use vs Q-Cells Q.TRON XL-G2.3 / BFG 640?
Q-Cells Q.TRON XL-G2.3 / BFG 620 uses N-type cells; Q-Cells Q.TRON XL-G2.3 / BFG 640 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 Q-Cells Q.TRON XL-G2.3 / BFG 620 and Q-Cells Q.TRON XL-G2.3 / BFG 640?
Q-Cells Q.TRON XL-G2.3 / BFG 620 has a 30 years power warranty; Q-Cells Q.TRON XL-G2.3 / BFG 640 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 Q-Cells Q.TRON XL-G2.3 / BFG 620 and Q-Cells Q.TRON XL-G2.3 / BFG 640 bifacial panels?
Both Q-Cells Q.TRON XL-G2.3 / BFG 620 and Q-Cells Q.TRON XL-G2.3 / BFG 640 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.

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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.