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RSF XL-G11S.3 / BFG 590 vs ML-G12S.3 / BFG 665 6 of 17 identical Swap Change panels

Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665

Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590
Q.PEAK DUO RSF XL-G11S.3 / BFG 590
590 Wp 21.10 % PERC Bifacial
Open panel page Datasheet PDF
VS
Q.PEAK DUO ML-G12S.3 / BFG 665
665 Wp 21.40 % Bifacial
Open panel page Datasheet PDF
The verdict

ML-G12S.3 / BFG 665 leads on the differences that matter

The largest is rated power: 75 W more power. 6 of 17 comparable parameters are identical, with 2 more left out because at least one datasheet does not publish them.

See all 11 differences
How alike are they
6 of 17 comparable
parameters are identical
identical differs not published
01

What actually differs

11 of 17 parameters
Parameter RSF XL-G11S.3 / BFG 590 ML-G12S.3 / BFG 665 Difference
Rated power 590 Wp 665 Wp 75 W more power
Open-circuit voltage 53.60 V 45.70 V 7.90 V apart
Short-circuit current 13.74 A 18.39 A 4.65 A apart
Module area 2.792 m² 3.106 m² 0.314 m² apart
Module efficiency 21.10 % 21.40 % 0.30 pp more efficient
Weight per kWp 61.7 kg/kWp 57.4 kg/kWp 4.3 kg/kWp lighter
Weight 36.4 kg 38.2 kg 1.8 kg lighter
Voltage at max power 44.96 V 38.11 V 6.85 V apart
Current at max power 13.12 A 17.45 A 4.33 A apart
Cell count 156 132 24 cells apart
Dimensions 2462x1134x35 mm 2384x1303x35 mm 2462x1134x35 mm vs 2384x1303x35 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 (-0.340 %/°C), so a warmer roof scales both curves by the same factor: the totals fall together and neither panel gains on the other.
RSF XL-G11S.3 / BFG 590
19,429 kWh
ML-G12S.3 / BFG 665
21,899 kWh
Lifetime gap
2,470 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario RSF XL-G11S.3 / BFG 590 ML-G12S.3 / BFG 665
Standard test conditions 25 °C 100.0% of rated power 590 W 665 W
Cool, bright day 40 °C 94.9% of rated power 560 W 631 W
Typical summer roof 55 °C 89.8% of rated power 530 W 597 W
Hot roof 70 °C 84.7% of rated power 500 W 563 W
03

Full specification

Parameter RSF XL-G11S.3 / BFG 590 ML-G12S.3 / BFG 665 Difference
Power and efficiency
Rated power 590 Wp 665 Wp +75 W for ML-G12S.3 / BFG 665
Module efficiency 21.10 % 21.40 % +0.30 pp for ML-G12S.3 / BFG 665
Power density 211.3 Wp/m² 214.1 Wp/m² Effectively the same
Open-circuit voltage 53.60 V 45.70 V 7.90 V apart
Voltage at max power 44.96 V 38.11 V 6.85 V apart
Short-circuit current 13.74 A 18.39 A 4.65 A apart
Current at max power 13.12 A 17.45 A 4.33 A apart
Temperature
Temperature coefficient -0.340 %/°C -0.340 %/°C Same
Mechanical
Dimensions 2462x1134x35 mm 2384x1303x35 mm 2462x1134x35 mm vs 2384x1303x35 mm
Module area 2.792 m² 3.106 m² 0.314 m² apart
Weight 36.4 kg 38.2 kg -1.8 kg for RSF XL-G11S.3 / BFG 590
Weight per kWp 61.7 kg/kWp 57.4 kg/kWp -4.3 kg/kWp for ML-G12S.3 / BFG 665
Warranty and degradation
Product warranty - 12 yrs Not published by Q-Cells
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.45 %/yr 0.45 %/yr Same
Technology
Cell technology PERC - Not published by Q-Cells
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
#9,297 vs #8,323
ML-G12S.3 / BFG 665 leads by 974 places
Power density
#9,241 vs #8,250
ML-G12S.3 / BFG 665 leads by 991 places
Heat behaviour
#8,778 vs #8,778
Tied - the same position in the database
Weight
#12,677 vs #11,217
ML-G12S.3 / BFG 665 leads by 1,460 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#8,523 vs #2,833
ML-G12S.3 / BFG 665 leads by 5,690 places
05

More useful comparisons

Open the full database
Same series, other bin
Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 vs Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 600
3 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 vs Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 595
One difference: module efficiency
Same series, other bin
Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 vs Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 585
The same specification on paper
Same series, other bin
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675
3 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670
One difference: module efficiency
Same series, other bin
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660
One difference: module efficiency
06

Written summary

07

Questions about this pairing

Which panel is better: Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 or Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665?
According to our database: Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 has higher module efficiency (21.40% vs 21.10%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665?
Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 has a module efficiency of 21.10%, while Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 is 21.40%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 use vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665?
Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 uses PERC cells; Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 uses Monocrystalline. 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.PEAK DUO RSF XL-G11S.3 / BFG 590 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665?
Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 has a 30 years power warranty; Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 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.PEAK DUO RSF XL-G11S.3 / BFG 590 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 bifacial panels?
Both Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 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.