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HIE-S405VG vs HiS-T640NJ 2 of 18 identical Swap Change panels

Hyundai HIE-S405VG vs Hyundai HiS-T640NJ

HIE-S405VG
405 Wp 20.70 % PERC
Open panel page Datasheet PDF
VS
HiS-T640NJ
640 Wp 22.90 % TOPCon Bifacial
Open panel page Datasheet PDF
The verdict

HiS-T640NJ leads on the differences that matter

The largest is module efficiency: 2.20 pp more efficient. 2 of 18 comparable parameters are identical, with 1 more left out because at least one datasheet does not publish it.

See all 16 differences
How alike are they
2 of 18 comparable
parameters are identical
identical differs not published
01

What actually differs

16 of 18 parameters
Parameter HIE-S405VG HiS-T640NJ Difference
Module efficiency 20.70 % 22.90 % 2.20 pp more efficient
Temperature coefficient -0.340 %/°C -0.290 %/°C 0.050 %/°C better in heat
Rated power 405 Wp 640 Wp 235 W more power
Power density 206.7 Wp/m² 229.0 Wp/m² 22.3 Wp/m² higher
Performance warranty 25 yrs 30 yrs 5 yrs longer
Annual degradation 0.55 %/yr 0.40 %/yr 0.15 %/yr slower
Weight 22.0 kg 34.7 kg 12.7 kg lighter
Product warranty 25 yrs 12 yrs 13 yrs longer
Open-circuit voltage 46.50 V 57.77 V 11.27 V apart
Short-circuit current 11.02 A 14.06 A 3.04 A apart
Module area 1.960 m² 2.795 m² 0.836 m² apart
Cell technology PERC TOPCon PERC vs TOPCon
Voltage at max power 38.70 V 47.74 V 9.04 V apart
Current at max power 10.47 A 13.41 A 2.94 A apart
Bifacial No Yes No vs Yes
Dimensions 1719x1140x35 mm 2465x1134x30 mm 1719x1140x35 mm vs 2465x1134x30 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
HIE-S405VG
13,126 kWh
HiS-T640NJ
21,473 kWh
Lifetime gap
8,347 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario HIE-S405VG HiS-T640NJ
Standard test conditions 25 °C 100.0% of rated power 405 W 640 W
Cool, bright day 40 °C 94.9% of rated power 384 W 612 W
Typical summer roof 55 °C 89.8% of rated power 364 W 584 W
Hot roof 70 °C 84.7% of rated power 343 W 556 W
03

Full specification

Parameter HIE-S405VG HiS-T640NJ Difference
Power and efficiency
Rated power 405 Wp 640 Wp +235 W for HiS-T640NJ
Module efficiency 20.70 % 22.90 % +2.20 pp for HiS-T640NJ
Power density 206.7 Wp/m² 229.0 Wp/m² +22.3 Wp/m² for HiS-T640NJ
Open-circuit voltage 46.50 V 57.77 V 11.27 V apart
Voltage at max power 38.70 V 47.74 V 9.04 V apart
Short-circuit current 11.02 A 14.06 A 3.04 A apart
Current at max power 10.47 A 13.41 A 2.94 A apart
Temperature
Temperature coefficient -0.340 %/°C -0.290 %/°C +0.050 %/°C for HiS-T640NJ
Mechanical
Dimensions 1719x1140x35 mm 2465x1134x30 mm 1719x1140x35 mm vs 2465x1134x30 mm
Module area 1.960 m² 2.795 m² 0.836 m² apart
Weight 22.0 kg 34.7 kg -12.7 kg for HIE-S405VG
Weight per kWp 54.3 kg/kWp 54.2 kg/kWp Effectively the same
Warranty and degradation
Product warranty 25 yrs 12 yrs +13 yrs for HIE-S405VG
Performance warranty 25 yrs 30 yrs +5 yrs for HiS-T640NJ
Annual degradation 0.55 %/yr 0.40 %/yr -0.15 %/yr for HiS-T640NJ
Technology
Cell technology PERC TOPCon PERC vs TOPCon
Cell type Monocrystalline Monocrystalline Same
Cell count - 156 Not published by Hyundai
Bifacial No Yes No vs Yes
04

Against the whole database

14,129 panels
Efficiency
#10,842 vs #2,412
HiS-T640NJ leads by 8,430 places
Power density
#11,043 vs #2,443
HiS-T640NJ leads by 8,600 places
Heat behaviour
#8,846 vs #2,220
HiS-T640NJ leads by 6,626 places
Weight
#8,666 vs #8,527
HiS-T640NJ leads by 139 places
Warranty
#9,912 vs #21
HiS-T640NJ leads by 9,891 places
Overall
#10,549 vs #2,117
HiS-T640NJ leads by 8,432 places
05

More useful comparisons

Open the full database
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Hyundai HIE-S405VG vs Hyundai HIE-S410VG
One difference: module efficiency
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Hyundai HIE-S405VG vs Hyundai HIE-S400VG
One difference: module efficiency
Same series, other bin
Hyundai HIE-S405VG vs Hyundai HIE-S395VG
3 differences, the largest is module efficiency
Same series, other bin
Hyundai HIE-S405VG vs Hyundai HIE-S390VG
4 differences, the largest is module efficiency
Same series, other bin
Hyundai HiS-T640NJ vs Hyundai HiS-T635NJ
The same specification on paper
Same series, other bin
Hyundai HiS-T640NJ vs Hyundai HiS-T630NJ
3 differences, the largest is module efficiency
06

Written summary

07

Questions about this pairing

Which panel is better: Hyundai HIE-S405VG or Hyundai HiS-T640NJ?
According to our database: Hyundai HiS-T640NJ has higher module efficiency (22.90% vs 20.70%); Hyundai HiS-T640NJ tolerates heat better (temp coeff -0.290%/°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 Hyundai HIE-S405VG and Hyundai HiS-T640NJ?
Hyundai HIE-S405VG has a module efficiency of 20.70%, while Hyundai HiS-T640NJ is 22.90%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Hyundai HIE-S405VG use vs Hyundai HiS-T640NJ?
Hyundai HIE-S405VG uses PERC cells; Hyundai HiS-T640NJ 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 Hyundai HIE-S405VG and Hyundai HiS-T640NJ?
Hyundai HIE-S405VG has a 25 years power warranty; Hyundai HiS-T640NJ 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 Hyundai HIE-S405VG and Hyundai HiS-T640NJ bifacial panels?
Hyundai HiS-T640NJ is bifacial (captures light from both faces); Hyundai HIE-S405VG 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.