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640 XL vs 620 XL 16 of 19 identical Swap Change panels

Silfab SIL-640 XL vs Silfab SIL-620 XL

Silfab
SIL-640 XL
640 Wp 22.92 % N-type Bifacial
Open panel page Datasheet PDF
VS
Silfab
SIL-620 XL
620 Wp 22.20 % N-type Bifacial
Open panel page Datasheet PDF
The verdict

640 XL leads on the differences that matter

The largest is module efficiency: 0.72 pp more efficient. 16 of 19 comparable parameters are identical.

See all 3 differences
How alike are they
16 of 19 comparable
parameters are identical
identical differs
01

What actually differs

3 of 19 parameters
Parameter 640 XL 620 XL Difference
Module efficiency 22.92 % 22.20 % 0.72 pp more efficient
Power density 229.2 Wp/m² 222.0 Wp/m² 7.2 Wp/m² higher
Rated power 640 Wp 620 Wp 20 W more power
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
620 XL
20,903 kWh
Lifetime gap
674 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 640 XL 620 XL
Standard test conditions 25 °C 100.0% of rated power 640 W 620 W
Cool, bright day 40 °C 95.7% of rated power 612 W 593 W
Typical summer roof 55 °C 91.3% of rated power 584 W 566 W
Hot roof 70 °C 87.0% of rated power 556 W 539 W
03

Full specification

Parameter 640 XL 620 XL Difference
Power and efficiency
Rated power 640 Wp 620 Wp +20 W for 640 XL
Module efficiency 22.92 % 22.20 % +0.72 pp for 640 XL
Power density 229.2 Wp/m² 222.0 Wp/m² +7.2 Wp/m² for 640 XL
Open-circuit voltage 57.76 V 57.21 V Effectively the same
Voltage at max power 48.78 V 48.16 V Effectively the same
Short-circuit current 13.76 A 13.55 A Effectively the same
Current at max power 13.12 A 12.87 A Effectively the same
Temperature
Temperature coefficient -0.290 %/°C -0.290 %/°C Same
Mechanical
Dimensions 2465x1133x35 mm 2465x1133x35 mm Same
Module area 2.793 m² 2.793 m² Same
Weight 29.5 kg 29.5 kg Same
Weight per kWp 46.1 kg/kWp 47.6 kg/kWp Effectively the same
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 156 156 Same
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#2,350 vs #5,817
640 XL leads by 3,467 places
Power density
#2,379 vs #5,849
640 XL leads by 3,470 places
Heat behaviour
#2,165 vs #2,165
Tied - the same position in the database
Weight
#1,004 vs #1,761
640 XL leads by 757 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#650 vs #1,404
640 XL leads by 754 places
05

More useful comparisons

Open the full database
Same series, other bin
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Silfab SIL-640 XL vs Silfab SIL-630 XL
3 differences, the largest is module efficiency
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Silfab SIL-640 XL vs Silfab SIL-590 XM+
8 differences, the largest is rated power
Same manufacturer
Silfab
Silfab SIL-640 XL vs Silfab SIL-580-XM+-BIFACIAL
10 differences, the largest is rated power
Same manufacturer
Silfab
Silfab SIL-640 XL vs Silfab SIL-570 XM+ BIFACIAL
10 differences, the largest is module efficiency
Same manufacturer
Silfab
Silfab SIL-640 XL vs Silfab SIL-570 XM+
10 differences, the largest is module efficiency
Same manufacturer
Silfab
Silfab SIL-640 XL vs Silfab SIL-540-XM-BIFACIAL
9 differences, the largest is rated power
06

Written summary

07

Questions about this pairing

Which panel is better: Silfab SIL-640 XL or Silfab SIL-620 XL?
According to our database: Silfab SIL-640 XL has higher module efficiency (22.92% vs 22.20%). 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-620 XL?
Silfab SIL-640 XL has a module efficiency of 22.92%, while Silfab SIL-620 XL is 22.20%. 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-620 XL?
Silfab SIL-640 XL uses N-type cells; Silfab SIL-620 XL 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-620 XL?
Silfab SIL-640 XL has a 30 years power warranty; Silfab SIL-620 XL 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-620 XL bifacial panels?
Both Silfab SIL-640 XL and Silfab SIL-620 XL 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.