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670M66-HUV vs 665NT66-HU/BF-DG 10 of 19 identical Swap Change panels

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

EGing PV EG-670M66-HUV
EGing PV
EG-670M66-HUV
670 Wp 21.56 % PERC
Open panel page Datasheet PDF
VS
EGing PV
EG-665NT66-HU/BF-DG
665 Wp 21.40 % TOPCon 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. 10 of 19 comparable parameters are identical.

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

What actually differs

9 of 19 parameters
Parameter 670M66-HUV 665NT66-HU/BF-DG Difference
Temperature coefficient -0.340 %/°C -0.300 %/°C 0.040 %/°C better in heat
Performance warranty 25 yrs 30 yrs 5 yrs longer
Annual degradation 0.55 %/yr 0.40 %/yr 0.15 %/yr slower
Weight 32.9 kg 38.3 kg 5.4 kg lighter
Weight per kWp 49.1 kg/kWp 57.6 kg/kWp 8.5 kg/kWp lighter
Cell technology PERC TOPCon PERC vs TOPCon
Bifacial No Yes No vs Yes
Short-circuit current 18.61 A 18.07 A 0.54 A apart
Current at max power 17.56 A 17.06 A 0.50 A apart
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
670M66-HUV
21,714 kWh
665NT66-HU/BF-DG
22,312 kWh
Lifetime gap
598 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 670M66-HUV 665NT66-HU/BF-DG
Standard test conditions 25 °C 100.0% of rated power 670 W 665 W
Cool, bright day 40 °C 94.9% of rated power 636 W 635 W
Typical summer roof 55 °C 89.8% of rated power 602 W 605 W
Hot roof 70 °C 84.7% of rated power 567 W 575 W
03

Full specification

Parameter 670M66-HUV 665NT66-HU/BF-DG Difference
Power and efficiency
Rated power 670 Wp 665 Wp Effectively the same
Module efficiency 21.56 % 21.40 % Effectively the same
Power density 215.7 Wp/m² 214.1 Wp/m² Effectively the same
Open-circuit voltage 45.97 V 46.78 V Effectively the same
Voltage at max power 38.16 V 38.99 V Effectively the same
Short-circuit current 18.61 A 18.07 A 0.54 A apart
Current at max power 17.56 A 17.06 A 0.50 A apart
Temperature
Temperature coefficient -0.340 %/°C -0.300 %/°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 32.9 kg 38.3 kg -5.4 kg for 670M66-HUV
Weight per kWp 49.1 kg/kWp 57.6 kg/kWp -8.5 kg/kWp for 670M66-HUV
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 25 yrs 30 yrs +5 yrs for 665NT66-HU/BF-DG
Annual degradation 0.55 %/yr 0.40 %/yr -0.15 %/yr for 665NT66-HU/BF-DG
Technology
Cell technology PERC TOPCon PERC vs TOPCon
Cell type Monocrystalline Monocrystalline Same
Cell count 132 132 Same
Bifacial No Yes No vs Yes
04

Against the whole database

14,005 panels
Efficiency
#7,774 vs #8,323
670M66-HUV leads by 549 places
Power density
#7,644 vs #8,250
670M66-HUV leads by 606 places
Heat behaviour
#8,778 vs #6,093
665NT66-HU/BF-DG leads by 2,685 places
Weight
#2,745 vs #11,303
670M66-HUV leads by 8,558 places
Warranty
#9,798 vs #21
665NT66-HU/BF-DG leads by 9,777 places
Overall
#3,378 vs #2,833
665NT66-HU/BF-DG leads by 545 places
05

More useful comparisons

Open the full database
Same series, other bin
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EGing PV EG-670M66-HUV vs EGing PV EG-685NT66-HU/BF-DG
12 differences, the largest is temperature coefficient
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EGing PV EG-670M66-HUV vs EGing PV EG-680NT66-HU/BF-DG
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EGing PV EG-670M66-HUV vs EGing PV EG-675NT66-HU/BF-DG
9 differences, the largest is temperature coefficient
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EGing PV EG-670M66-HUV vs EGing PV EG-670NT66-HU/BF-DG
10 differences, the largest is temperature coefficient
Same series, other bin
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EGing PV EG-670M66-HUV vs EGing PV EG-670M66-HU/BF-DG
5 differences, the largest is performance warranty
Same series, other bin
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EGing PV EG-670M66-HUV vs EGing PV EG-665M66-HU/BF-DG
5 differences, the largest is performance warranty
06

Written summary

07

Questions about this pairing

Which panel is better: EGing PV EG-670M66-HUV or EGing PV EG-665NT66-HU/BF-DG?
According to our database: EGing PV EG-670M66-HUV 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-670M66-HUV and EGing PV EG-665NT66-HU/BF-DG?
EGing PV EG-670M66-HUV has a module efficiency of 21.56%, while EGing PV EG-665NT66-HU/BF-DG is 21.40%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does EGing PV EG-670M66-HUV use vs EGing PV EG-665NT66-HU/BF-DG?
EGing PV EG-670M66-HUV uses PERC cells; EGing PV EG-665NT66-HU/BF-DG uses TOPCon. 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-670M66-HUV and EGing PV EG-665NT66-HU/BF-DG?
EGing PV EG-670M66-HUV has a 25 years power warranty; EGing PV EG-665NT66-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-670M66-HUV and EGing PV EG-665NT66-HU/BF-DG bifacial panels?
EGing PV EG-665NT66-HU/BF-DG is bifacial (captures light from both faces); EGing PV EG-670M66-HUV is monofacial. Bifacial panels work best on ground mounts or raised structures with a light-coloured surface underneath.

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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.