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645 vs 640 18 of 19 identical Swap Change panels

Q-Cells Q.TRON XL-G2.3 / BFG 645 vs Q-Cells Q.TRON XL-G2.3 / BFG 640

Q-Cells Q.TRON XL-G2.3 / BFG 645
Q.TRON XL-G2.3 / BFG 645
645 Wp 23.10 % 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

645 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 645 640 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
21,761 kWh
640
21,592 kWh
Lifetime gap
169 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 645 640
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 645 640 Difference
Power and efficiency
Rated power 645 Wp 640 Wp Effectively the same
Module efficiency 23.10 % 22.90 % +0.20 pp for 645
Power density 231.0 Wp/m² 229.2 Wp/m² Effectively the same
Open-circuit voltage 58.07 V 57.79 V Effectively the same
Voltage at max power 48.47 V 48.28 V Effectively the same
Short-circuit current 14.05 A 13.99 A Effectively the same
Current at max power 13.31 A 13.26 A Effectively the same
Temperature
Temperature coefficient -0.290 %/°C -0.290 %/°C Same
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 54.9 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
#1,570 vs #2,359
645 leads by 789 places
Power density
#1,629 vs #2,368
645 leads by 739 places
Heat behaviour
#2,165 vs #2,165
Tied - the same position in the database
Weight
#9,271 vs #9,773
645 leads by 502 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#1,826 vs #2,116
645 leads by 290 places
05

More useful comparisons

Open the full database
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 645 vs Q-Cells Q.TRON XL-G2.3 / BFG 635
4 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 645 vs Q-Cells Q.TRON XL-G2.3 / BFG 630
4 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 645 vs Q-Cells Q.TRON XL-G2.3 / BFG 625
5 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 645 vs Q-Cells Q.TRON XL-G2.3 / BFG 620
6 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 645 vs Q-Cells Q.TRON XL-G2.3 / BFG 615
7 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.TRON XL-G2.3 / BFG 645 vs Q-Cells Q.TRON XL-G2.3 / BFG 610
7 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 645 or Q-Cells Q.TRON XL-G2.3 / BFG 640?
According to our database: Q-Cells Q.TRON XL-G2.3 / BFG 645 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 Q-Cells Q.TRON XL-G2.3 / BFG 645 and Q-Cells Q.TRON XL-G2.3 / BFG 640?
Q-Cells Q.TRON XL-G2.3 / BFG 645 has a module efficiency of 23.10%, 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 645 use vs Q-Cells Q.TRON XL-G2.3 / BFG 640?
Q-Cells Q.TRON XL-G2.3 / BFG 645 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 645 and Q-Cells Q.TRON XL-G2.3 / BFG 640?
Q-Cells Q.TRON XL-G2.3 / BFG 645 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 645 and Q-Cells Q.TRON XL-G2.3 / BFG 640 bifacial panels?
Both Q-Cells Q.TRON XL-G2.3 / BFG 645 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.