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655 vs 670 15 of 18 identical Swap Change panels

Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670

Q.PEAK DUO ML-G12S.3 / BFG 655
655 Wp 21.10 % Bifacial
Open panel page Datasheet PDF
VS
Q.PEAK DUO ML-G12S.3 / BFG 670
670 Wp 21.60 % Bifacial
Open panel page Datasheet PDF
The verdict

670 leads on the differences that matter

The largest is module efficiency: 0.50 pp more efficient. 15 of 18 comparable parameters are identical, with 1 more left out because at least one datasheet does not publish it.

See all 3 differences
How alike are they
15 of 18 comparable
parameters are identical
identical differs not published
01

What actually differs

3 of 18 parameters
Parameter 655 670 Difference
Module efficiency 21.10 % 21.60 % 0.50 pp more efficient
Power density 210.9 Wp/m² 215.7 Wp/m² 4.8 Wp/m² higher
Rated power 655 Wp 670 Wp 15 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 (-0.340 %/°C), so a warmer roof scales both curves by the same factor: the totals fall together and neither panel gains on the other.
655
21,570 kWh
670
22,064 kWh
Lifetime gap
494 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 655 670
Standard test conditions 25 °C 100.0% of rated power 655 W 670 W
Cool, bright day 40 °C 94.9% of rated power 622 W 636 W
Typical summer roof 55 °C 89.8% of rated power 588 W 602 W
Hot roof 70 °C 84.7% of rated power 555 W 567 W
03

Full specification

Parameter 655 670 Difference
Power and efficiency
Rated power 655 Wp 670 Wp +15 W for 670
Module efficiency 21.10 % 21.60 % +0.50 pp for 670
Power density 210.9 Wp/m² 215.7 Wp/m² +4.8 Wp/m² for 670
Open-circuit voltage 45.66 V 45.72 V Effectively the same
Voltage at max power 37.78 V 38.27 V Effectively the same
Short-circuit current 18.33 A 18.42 A Effectively the same
Current at max power 17.34 A 17.51 A Effectively the same
Temperature
Temperature coefficient -0.340 %/°C -0.340 %/°C Same
Mechanical
Dimensions 2384x1303x35 mm 2384x1303x35 mm Same
Module area 3.106 m² 3.106 m² Same
Weight 38.2 kg 38.2 kg Same
Weight per kWp 58.3 kg/kWp 57.0 kg/kWp Effectively the same
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.45 %/yr 0.45 %/yr Same
Technology
Cell technology - - Neither datasheet publishes this
Cell type Monocrystalline Monocrystalline Same
Cell count 132 132 Same
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#9,297 vs #7,652
670 leads by 1,645 places
Power density
#9,459 vs #7,644
670 leads by 1,815 places
Heat behaviour
#8,778 vs #8,778
Tied - the same position in the database
Weight
#11,654 vs #11,008
670 leads by 646 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#3,525 vs #2,462
670 leads by 1,063 places
05

More useful comparisons

Open the full database
Same series, other bin
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655 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 655 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665
3 differences, the largest is module efficiency
Same series, other bin
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660
The same specification on paper
Same series, other bin
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 650
One difference: module efficiency
Same manufacturer
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655 vs Q-Cells Q.TRON XL-G2.3 / BFG 645
14 differences, the largest is module efficiency
Same manufacturer
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655 vs Q-Cells Q.TRON XL-G2.3 / BFG 640
14 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 655 or Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670?
According to our database: Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670 has higher module efficiency (21.60% 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 655 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670?
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655 has a module efficiency of 21.10%, while Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670 is 21.60%. 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 655 use vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670?
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655 uses Monocrystalline cells; Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670 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 ML-G12S.3 / BFG 655 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670?
Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655 has a 30 years power warranty; Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670 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 655 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670 bifacial panels?
Both Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670 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.