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640 XL vs 540-XM-BIFACIAL 10 of 19 identical Swap Change panels

Silfab SIL-640 XL vs Silfab SIL-540-XM-BIFACIAL

Silfab
SIL-640 XL
640 Wp 22.92 % N-type Bifacial
Open panel page Datasheet PDF
VS
Silfab
SIL-540-XM-BIFACIAL
540 Wp 22.70 % N-type Bifacial
Open panel page Datasheet PDF
The verdict

640 XL leads on the differences that matter

The largest is rated power: 100 W more power. 10 of 19 comparable parameters are identical.

See all 9 differences
How alike are they
10 of 19 comparable
parameters are identical
identical differs
01

What actually differs

9 of 19 parameters
Parameter 640 XL 540-XM-BIFACIAL Difference
Rated power 640 Wp 540 Wp 100 W more power
Weight 29.5 kg 26.2 kg 3.3 kg lighter
Open-circuit voltage 57.76 V 47.95 V 9.81 V apart
Module area 2.793 m² 2.377 m² 0.416 m² apart
Module efficiency 22.92 % 22.70 % 0.22 pp more efficient
Voltage at max power 48.78 V 41.62 V 7.16 V apart
Cell count 156 132 24 cells apart
Weight per kWp 46.1 kg/kWp 48.5 kg/kWp 2.4 kg/kWp lighter
Dimensions 2465x1133x35 mm 2098x1133x35 mm 2465x1133x35 mm vs 2098x1133x35 mm
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 XL
21,577 kWh
540-XM-BIFACIAL
18,206 kWh
Lifetime gap
3,371 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 640 XL 540-XM-BIFACIAL
Standard test conditions 25 °C 100.0% of rated power 640 W 540 W
Cool, bright day 40 °C 95.7% of rated power 612 W 517 W
Typical summer roof 55 °C 91.3% of rated power 584 W 493 W
Hot roof 70 °C 87.0% of rated power 556 W 470 W
03

Full specification

Parameter 640 XL 540-XM-BIFACIAL Difference
Power and efficiency
Rated power 640 Wp 540 Wp +100 W for 640 XL
Module efficiency 22.92 % 22.70 % +0.22 pp for 640 XL
Power density 229.2 Wp/m² 227.2 Wp/m² Effectively the same
Open-circuit voltage 57.76 V 47.95 V 9.81 V apart
Voltage at max power 48.78 V 41.62 V 7.16 V apart
Short-circuit current 13.76 A 13.78 A Effectively the same
Current at max power 13.12 A 12.97 A Effectively the same
Temperature
Temperature coefficient -0.290 %/°C -0.290 %/°C Same
Mechanical
Dimensions 2465x1133x35 mm 2098x1133x35 mm 2465x1133x35 mm vs 2098x1133x35 mm
Module area 2.793 m² 2.377 m² 0.416 m² apart
Weight 29.5 kg 26.2 kg -3.3 kg for 540-XM-BIFACIAL
Weight per kWp 46.1 kg/kWp 48.5 kg/kWp -2.4 kg/kWp for 640 XL
Warranty and degradation
Product warranty 25 yrs 25 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.30 %/yr 0.30 %/yr Same
Technology
Cell technology N-type N-type Same
Cell type Monocrystalline Monocrystalline Same
Cell count 156 132 24 cells apart
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#2,350 vs #3,307
640 XL leads by 957 places
Power density
#2,379 vs #3,251
640 XL leads by 872 places
Heat behaviour
#2,165 vs #2,165
Tied - the same position in the database
Weight
#1,004 vs #2,336
640 XL leads by 1,332 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#650 vs #2,857
640 XL leads by 2,207 places
05

More useful comparisons

Open the full database
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Silfab SIL-640 XL vs Silfab SIL-630 XL
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Silfab SIL-640 XL vs Silfab SIL-620 XL
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Silfab SIL-540-XM-BIFACIAL vs Silfab SIL-590 XM+
7 differences, the largest is rated power
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Silfab SIL-540-XM-BIFACIAL vs Silfab SIL-580-XM+-BIFACIAL
8 differences, the largest is rated power
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Silfab SIL-540-XM-BIFACIAL vs Silfab SIL-570 XM+ BIFACIAL
9 differences, the largest is module efficiency
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Silfab SIL-540-XM-BIFACIAL vs Silfab SIL-570 XM+
9 differences, the largest is module efficiency
06

Written summary

07

Questions about this pairing

Which panel is better: Silfab SIL-640 XL or Silfab SIL-540-XM-BIFACIAL?
According to our database: Silfab SIL-640 XL has higher module efficiency (22.92% vs 22.70%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Silfab SIL-640 XL and Silfab SIL-540-XM-BIFACIAL?
Silfab SIL-640 XL has a module efficiency of 22.92%, while Silfab SIL-540-XM-BIFACIAL is 22.70%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Silfab SIL-640 XL use vs Silfab SIL-540-XM-BIFACIAL?
Silfab SIL-640 XL uses N-type cells; Silfab SIL-540-XM-BIFACIAL 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 Silfab SIL-640 XL and Silfab SIL-540-XM-BIFACIAL?
Silfab SIL-640 XL has a 30 years power warranty; Silfab SIL-540-XM-BIFACIAL 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 Silfab SIL-640 XL and Silfab SIL-540-XM-BIFACIAL bifacial panels?
Both Silfab SIL-640 XL and Silfab SIL-540-XM-BIFACIAL 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.