Silfab SIL-620 XL vs Silfab SIL-420 QD
VS
The verdict
620 XL leads on the differences that matter
The largest is module efficiency: 0.70 pp more efficient. 7 of 19 comparable parameters are identical.
See all 12 differencesHow alike are they
7
of 19 comparable
parameters are identical
parameters are identical
identical
differs
01
12 of 19 parameters
What actually differs
Parameter
620 XL
420 QD
Difference
Module efficiency
22.20 %
21.50 %
0.70 pp more efficient
Rated power
620 Wp
420 Wp
200 W more power
Weight
29.5 kg
21.0 kg
8.5 kg lighter
Power density
222.0 Wp/m²
215.4 Wp/m²
6.6 Wp/m² higher
Annual degradation
0.30 %/yr
0.40 %/yr
0.10 %/yr slower
Open-circuit voltage
57.21 V
38.84 V
18.37 V apart
Module area
2.793 m²
1.950 m²
0.843 m² apart
Voltage at max power
48.16 V
33.08 V
15.08 V apart
Cell count
156
108
48 cells apart
Weight per kWp
47.6 kg/kWp
50.0 kg/kWp
2.4 kg/kWp lighter
Bifacial
Yes
No
Yes vs No
Dimensions
2465x1133x35 mm
1721x1133x35 mm
2465x1133x35 mm vs 1721x1133x35 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.
620 XL
20,903 kWh
420 QD
13,941 kWh
Lifetime gap
6,962 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario
620 XL
420 QD
Standard test conditions
25 °C
100.0% of rated power
620 W
420 W
Cool, bright day
40 °C
95.7% of rated power
593 W
402 W
Typical summer roof
55 °C
91.3% of rated power
566 W
383 W
Hot roof
70 °C
87.0% of rated power
539 W
365 W
03
Full specification
Parameter
620 XL
420 QD
Difference
Power and efficiency
Rated power
620 Wp
420 Wp
+200 W for 620 XL
Module efficiency
22.20 %
21.50 %
+0.70 pp for 620 XL
Power density
222.0 Wp/m²
215.4 Wp/m²
+6.6 Wp/m² for 620 XL
Open-circuit voltage
57.21 V
38.84 V
18.37 V apart
Voltage at max power
48.16 V
33.08 V
15.08 V apart
Short-circuit current
13.55 A
13.50 A
Effectively the same
Current at max power
12.87 A
12.70 A
Effectively the same
Temperature
Temperature coefficient
-0.290 %/°C
-0.290 %/°C
Same
Mechanical
Dimensions
2465x1133x35 mm
1721x1133x35 mm
2465x1133x35 mm vs 1721x1133x35 mm
Module area
2.793 m²
1.950 m²
0.843 m² apart
Weight
29.5 kg
21.0 kg
-8.5 kg for 420 QD
Weight per kWp
47.6 kg/kWp
50.0 kg/kWp
-2.4 kg/kWp for 620 XL
Warranty and degradation
Product warranty
25 yrs
25 yrs
Same
Performance warranty
30 yrs
30 yrs
Same
Annual degradation
0.30 %/yr
0.40 %/yr
-0.10 %/yr for 620 XL
Technology
Cell technology
N-type
N-type
Same
Cell type
Monocrystalline
Monocrystalline
Same
Cell count
156
108
48 cells apart
Bifacial
Yes
No
Yes vs No
04
14,005 panels
Against the whole database
Efficiency
#5,817
vs
#7,958
620 XL leads by 2,141 places
Power density
#5,849
vs
#7,783
620 XL leads by 1,934 places
Heat behaviour
#2,165
vs
#2,165
Tied - the same position in the database
Weight
#1,761
vs
#3,317
620 XL leads by 1,556 places
Warranty
#21
vs
#21
Tied - the same position in the database
Overall
#1,404
vs
#8,547
620 XL leads by 7,143 places
05
Open the full database
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06
Written summary
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07
Questions about this pairing
Which panel is better: Silfab SIL-620 XL or Silfab SIL-420 QD?
According to our database: Silfab SIL-620 XL has higher module efficiency (22.20% vs 21.50%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Silfab SIL-620 XL and Silfab SIL-420 QD?
Silfab SIL-620 XL has a module efficiency of 22.20%, while Silfab SIL-420 QD is 21.50%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Silfab SIL-620 XL use vs Silfab SIL-420 QD?
Silfab SIL-620 XL uses N-type cells; Silfab SIL-420 QD 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-620 XL and Silfab SIL-420 QD?
Silfab SIL-620 XL has a 30 years power warranty; Silfab SIL-420 QD 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-620 XL and Silfab SIL-420 QD bifacial panels?
Silfab SIL-620 XL is bifacial (captures light from both faces); Silfab SIL-420 QD is monofacial. Bifacial panels work best on ground mounts or raised structures with a light-coloured surface underneath.
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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.