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665NT66-HU/BF-DG vs 670M66-HU/BF-DG 16 of 19 identical Swap Change panels

EGing PV EG-665NT66-HU/BF-DG vs EGing PV EG-670M66-HU/BF-DG

EGing PV
EG-665NT66-HU/BF-DG
665 Wp 21.40 % TOPCon Bifacial
Open panel page Datasheet PDF
VS
EGing PV
EG-670M66-HU/BF-DG
670 Wp 21.56 % PERC Bifacial
Open panel page Datasheet PDF
The verdict

665NT66-HU/BF-DG leads on the differences that matter

The largest is temperature coefficient: 0.040 %/°C better in heat. 16 of 19 comparable parameters are identical.

See all 3 differences
How alike are they
16 of 19 comparable
parameters are identical
identical differs
01

What actually differs

3 of 19 parameters
Parameter 665NT66-HU/BF-DG 670M66-HU/BF-DG Difference
Temperature coefficient -0.300 %/°C -0.340 %/°C 0.040 %/°C better in heat
Cell technology TOPCon PERC TOPCon vs PERC
Annual degradation 0.40 %/yr 0.45 %/yr 0.05 %/yr slower
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
665NT66-HU/BF-DG
22,312 kWh
670M66-HU/BF-DG
22,064 kWh
Lifetime gap
248 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 665NT66-HU/BF-DG 670M66-HU/BF-DG
Standard test conditions 25 °C 100.0% of rated power 665 W 670 W
Cool, bright day 40 °C 94.9% of rated power 635 W 636 W
Typical summer roof 55 °C 89.8% of rated power 605 W 602 W
Hot roof 70 °C 84.7% of rated power 575 W 567 W
03

Full specification

Parameter 665NT66-HU/BF-DG 670M66-HU/BF-DG Difference
Power and efficiency
Rated power 665 Wp 670 Wp Effectively the same
Module efficiency 21.40 % 21.56 % Effectively the same
Power density 214.1 Wp/m² 215.7 Wp/m² Effectively the same
Open-circuit voltage 46.78 V 46.20 V Effectively the same
Voltage at max power 38.99 V 38.38 V Effectively the same
Short-circuit current 18.07 A 18.51 A Effectively the same
Current at max power 17.06 A 17.46 A Effectively the same
Temperature
Temperature coefficient -0.300 %/°C -0.340 %/°C +0.040 %/°C for 665NT66-HU/BF-DG
Mechanical
Dimensions 2384x1303x35 mm 2384x1303x35 mm Same
Module area 3.106 m² 3.106 m² Same
Weight 38.3 kg 38.3 kg Same
Weight per kWp 57.6 kg/kWp 57.2 kg/kWp Effectively the same
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.40 %/yr 0.45 %/yr -0.05 %/yr for 665NT66-HU/BF-DG
Technology
Cell technology TOPCon PERC TOPCon vs PERC
Cell type Monocrystalline Monocrystalline Same
Cell count 132 132 Same
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#8,323 vs #7,774
670M66-HU/BF-DG leads by 549 places
Power density
#8,250 vs #7,644
670M66-HU/BF-DG leads by 606 places
Heat behaviour
#6,093 vs #8,778
665NT66-HU/BF-DG leads by 2,685 places
Weight
#11,303 vs #11,112
670M66-HU/BF-DG leads by 191 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#2,833 vs #2,497
670M66-HU/BF-DG leads by 336 places
05

More useful comparisons

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06

Written summary

07

Questions about this pairing

Which panel is better: EGing PV EG-665NT66-HU/BF-DG or EGing PV EG-670M66-HU/BF-DG?
According to our database: EGing PV EG-670M66-HU/BF-DG has higher module efficiency (21.56% vs 21.40%); EGing PV EG-665NT66-HU/BF-DG tolerates heat better (temp coeff -0.300%/°C vs -0.340%/°C). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of EGing PV EG-665NT66-HU/BF-DG and EGing PV EG-670M66-HU/BF-DG?
EGing PV EG-665NT66-HU/BF-DG has a module efficiency of 21.40%, while EGing PV EG-670M66-HU/BF-DG is 21.56%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does EGing PV EG-665NT66-HU/BF-DG use vs EGing PV EG-670M66-HU/BF-DG?
EGing PV EG-665NT66-HU/BF-DG uses TOPCon cells; EGing PV EG-670M66-HU/BF-DG 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 EGing PV EG-665NT66-HU/BF-DG and EGing PV EG-670M66-HU/BF-DG?
EGing PV EG-665NT66-HU/BF-DG has a 30 years power warranty; EGing PV EG-670M66-HU/BF-DG 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 EGing PV EG-665NT66-HU/BF-DG and EGing PV EG-670M66-HU/BF-DG bifacial panels?
Both EGing PV EG-665NT66-HU/BF-DG and EGing PV EG-670M66-HU/BF-DG 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.