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370 BK vs 420-BG 9 of 19 identical Swap Change panels

Silfab SIL-370 BK vs Silfab SIL-420-BG

Silfab
SIL-370 BK
370 Wp 20.80 % PERC
Open panel page Datasheet PDF
VS
Silfab
SIL-420-BG
420 Wp 21.90 % PERC
Open panel page Datasheet PDF
The verdict

420-BG leads on the differences that matter

The largest is module efficiency: 1.10 pp more efficient. 9 of 19 comparable parameters are identical.

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

What actually differs

10 of 19 parameters
Parameter 370 BK 420-BG Difference
Module efficiency 20.80 % 21.90 % 1.10 pp more efficient
Rated power 370 Wp 420 Wp 50 W more power
Annual degradation 0.50 %/yr 0.30 %/yr 0.20 %/yr slower
Power density 208.2 Wp/m² 219.0 Wp/m² 10.8 Wp/m² higher
Module area 1.777 m² 1.918 m² 0.141 m² apart
Weight 19.0 kg 20.8 kg 1.8 kg lighter
Short-circuit current 10.33 A 11.40 A 1.07 A apart
Open-circuit voltage 44.76 V 46.36 V 1.60 V apart
Current at max power 9.69 A 10.91 A 1.22 A apart
Dimensions 1795x990x38 mm 1864x1029x35 mm 1795x990x38 mm vs 1864x1029x35 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 (-0.377 %/°C), so a warmer roof scales both curves by the same factor: the totals fall together and neither panel gains on the other.
370 BK
11,968 kWh
420-BG
14,160 kWh
Lifetime gap
2,192 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 370 BK 420-BG
Standard test conditions 25 °C 100.0% of rated power 370 W 420 W
Cool, bright day 40 °C 94.3% of rated power 349 W 396 W
Typical summer roof 55 °C 88.7% of rated power 328 W 372 W
Hot roof 70 °C 83.0% of rated power 307 W 349 W
03

Full specification

Parameter 370 BK 420-BG Difference
Power and efficiency
Rated power 370 Wp 420 Wp +50 W for 420-BG
Module efficiency 20.80 % 21.90 % +1.10 pp for 420-BG
Power density 208.2 Wp/m² 219.0 Wp/m² +10.8 Wp/m² for 420-BG
Open-circuit voltage 44.76 V 46.36 V 1.60 V apart
Voltage at max power 38.34 V 38.51 V Effectively the same
Short-circuit current 10.33 A 11.40 A 1.07 A apart
Current at max power 9.69 A 10.91 A 1.22 A apart
Temperature
Temperature coefficient -0.377 %/°C -0.377 %/°C Same
Mechanical
Dimensions 1795x990x38 mm 1864x1029x35 mm 1795x990x38 mm vs 1864x1029x35 mm
Module area 1.777 m² 1.918 m² 0.141 m² apart
Weight 19.0 kg 20.8 kg -1.8 kg for 370 BK
Weight per kWp 51.4 kg/kWp 49.5 kg/kWp Effectively the same
Warranty and degradation
Product warranty 25 yrs 25 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.50 %/yr 0.30 %/yr -0.20 %/yr for 420-BG
Technology
Cell technology PERC PERC Same
Cell type Monocrystalline Monocrystalline Same
Cell count 66 66 Same
Bifacial No No Same
04

Against the whole database

14,129 panels
Efficiency
#10,533 vs #6,847
420-BG leads by 3,686 places
Power density
#10,528 vs #6,850
420-BG leads by 3,678 places
Heat behaviour
#13,470 vs #13,470
Tied - the same position in the database
Weight
#4,742 vs #3,065
420-BG leads by 1,677 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#10,529 vs #8,049
420-BG leads by 2,480 places
05

More useful comparisons

Open the full database
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Silfab SIL-370 BK vs Silfab SIL-410-BG
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Silfab SIL-370 BK vs Silfab SIL-380 BK
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Silfab SIL-370 BK vs Silfab SIL-640 XL
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Silfab SIL-370 BK vs Silfab SIL-630 XL
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Silfab SIL-370 BK vs Silfab SIL-620 XL
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06

Written summary

07

Questions about this pairing

Which panel is better: Silfab SIL-370 BK or Silfab SIL-420-BG?
According to our database: Silfab SIL-420-BG has higher module efficiency (21.90% vs 20.80%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Silfab SIL-370 BK and Silfab SIL-420-BG?
Silfab SIL-370 BK has a module efficiency of 20.80%, while Silfab SIL-420-BG is 21.90%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Silfab SIL-370 BK use vs Silfab SIL-420-BG?
Silfab SIL-370 BK uses PERC cells; Silfab SIL-420-BG uses PERC. 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-370 BK and Silfab SIL-420-BG?
Silfab SIL-370 BK has a 30 years power warranty; Silfab SIL-420-BG 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.

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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.