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ML-G12S.3 / BFG 660 vs RSF XL-G11S.3 / BFG 590 7 of 17 identical Swap Change panels

Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 vs Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590

Q.PEAK DUO ML-G12S.3 / BFG 660
660 Wp 21.20 % Bifacial
Open panel page Datasheet PDF
VS
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
The verdict

ML-G12S.3 / BFG 660 leads on the differences that matter

The largest is rated power: 70 W more power. 7 of 17 comparable parameters are identical, with 2 more left out because at least one datasheet does not publish them.

See all 10 differences
How alike are they
7 of 17 comparable
parameters are identical
identical differs not published
01

What actually differs

10 of 17 parameters
Parameter ML-G12S.3 / BFG 660 RSF XL-G11S.3 / BFG 590 Difference
Rated power 660 Wp 590 Wp 70 W more power
Open-circuit voltage 45.68 V 53.60 V 7.92 V apart
Short-circuit current 18.36 A 13.74 A 4.62 A apart
Module area 3.106 m² 2.792 m² 0.314 m² apart
Weight per kWp 57.9 kg/kWp 61.7 kg/kWp 3.8 kg/kWp lighter
Weight 38.2 kg 36.4 kg 1.8 kg lighter
Voltage at max power 37.94 V 44.96 V 7.02 V apart
Current at max power 17.39 A 13.12 A 4.27 A apart
Cell count 132 156 24 cells apart
Dimensions 2384x1303x35 mm 2462x1134x35 mm 2384x1303x35 mm vs 2462x1134x35 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.
ML-G12S.3 / BFG 660
21,734 kWh
RSF XL-G11S.3 / BFG 590
19,429 kWh
Lifetime gap
2,305 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario ML-G12S.3 / BFG 660 RSF XL-G11S.3 / BFG 590
Standard test conditions 25 °C 100.0% of rated power 660 W 590 W
Cool, bright day 40 °C 94.9% of rated power 626 W 560 W
Typical summer roof 55 °C 89.8% of rated power 593 W 530 W
Hot roof 70 °C 84.7% of rated power 559 W 500 W
03

Full specification

Parameter ML-G12S.3 / BFG 660 RSF XL-G11S.3 / BFG 590 Difference
Power and efficiency
Rated power 660 Wp 590 Wp +70 W for ML-G12S.3 / BFG 660
Module efficiency 21.20 % 21.10 % Effectively the same
Power density 212.5 Wp/m² 211.3 Wp/m² Effectively the same
Open-circuit voltage 45.68 V 53.60 V 7.92 V apart
Voltage at max power 37.94 V 44.96 V 7.02 V apart
Short-circuit current 18.36 A 13.74 A 4.62 A apart
Current at max power 17.39 A 13.12 A 4.27 A apart
Temperature
Temperature coefficient -0.340 %/°C -0.340 %/°C Same
Mechanical
Dimensions 2384x1303x35 mm 2462x1134x35 mm 2384x1303x35 mm vs 2462x1134x35 mm
Module area 3.106 m² 2.792 m² 0.314 m² apart
Weight 38.2 kg 36.4 kg -1.8 kg for RSF XL-G11S.3 / BFG 590
Weight per kWp 57.9 kg/kWp 61.7 kg/kWp -3.8 kg/kWp for ML-G12S.3 / BFG 660
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 132 156 24 cells apart
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#9,076 vs #9,297
ML-G12S.3 / BFG 660 leads by 221 places
Power density
#8,959 vs #9,241
ML-G12S.3 / BFG 660 leads by 282 places
Heat behaviour
#8,778 vs #8,778
Tied - the same position in the database
Weight
#11,467 vs #12,677
ML-G12S.3 / BFG 660 leads by 1,210 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#3,228 vs #8,523
ML-G12S.3 / BFG 660 leads by 5,295 places
05

More useful comparisons

Open the full database
Same series, other bin
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675
3 differences, the largest is module efficiency
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Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670
3 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665
One difference: module efficiency
Same series, other bin
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655
The same specification on paper
Same series, other bin
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 650
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 600
3 differences, the largest is module efficiency
06

Written summary

07

Questions about this pairing

Which panel is better: Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 or Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590?
According to our database: Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 has higher module efficiency (21.20% 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 ML-G12S.3 / BFG 660 and Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590?
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 has a module efficiency of 21.20%, while Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 is 21.10%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 use vs Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590?
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 uses Monocrystalline cells; Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 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 Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 and Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590?
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 has a 30 years power warranty; Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 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 ML-G12S.3 / BFG 660 and Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 bifacial panels?
Both Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660 and Q-Cells Q.PEAK DUO RSF XL-G11S.3 / BFG 590 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.