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HiS-T640NJ vs HIE-S400VG 2 of 18 identical Swap Change panels

Hyundai HiS-T640NJ vs Hyundai HIE-S400VG

HiS-T640NJ
640 Wp 22.90 % TOPCon Bifacial
Open panel page Datasheet PDF
VS
HIE-S400VG
400 Wp 20.40 % PERC
Open panel page Datasheet PDF
The verdict

HiS-T640NJ leads on the differences that matter

The largest is module efficiency: 2.50 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 HiS-T640NJ HIE-S400VG Difference
Module efficiency 22.90 % 20.40 % 2.50 pp more efficient
Temperature coefficient -0.290 %/°C -0.340 %/°C 0.050 %/°C better in heat
Rated power 640 Wp 400 Wp 240 W more power
Power density 229.0 Wp/m² 204.1 Wp/m² 24.8 Wp/m² higher
Performance warranty 30 yrs 25 yrs 5 yrs longer
Annual degradation 0.40 %/yr 0.55 %/yr 0.15 %/yr slower
Weight 34.7 kg 22.0 kg 12.7 kg lighter
Product warranty 12 yrs 25 yrs 13 yrs longer
Open-circuit voltage 57.77 V 46.40 V 11.37 V apart
Short-circuit current 14.06 A 10.97 A 3.09 A apart
Module area 2.795 m² 1.960 m² 0.836 m² apart
Cell technology TOPCon PERC TOPCon vs PERC
Voltage at max power 47.74 V 38.60 V 9.14 V apart
Current at max power 13.41 A 10.36 A 3.05 A apart
Bifacial Yes No Yes vs No
Dimensions 2465x1134x30 mm 1719x1140x35 mm 2465x1134x30 mm vs 1719x1140x35 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
HiS-T640NJ
21,473 kWh
HIE-S400VG
12,964 kWh
Lifetime gap
8,509 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario HiS-T640NJ HIE-S400VG
Standard test conditions 25 °C 100.0% of rated power 640 W 400 W
Cool, bright day 40 °C 94.9% of rated power 612 W 380 W
Typical summer roof 55 °C 89.8% of rated power 584 W 359 W
Hot roof 70 °C 84.7% of rated power 556 W 339 W
03

Full specification

Parameter HiS-T640NJ HIE-S400VG Difference
Power and efficiency
Rated power 640 Wp 400 Wp +240 W for HiS-T640NJ
Module efficiency 22.90 % 20.40 % +2.50 pp for HiS-T640NJ
Power density 229.0 Wp/m² 204.1 Wp/m² +24.8 Wp/m² for HiS-T640NJ
Open-circuit voltage 57.77 V 46.40 V 11.37 V apart
Voltage at max power 47.74 V 38.60 V 9.14 V apart
Short-circuit current 14.06 A 10.97 A 3.09 A apart
Current at max power 13.41 A 10.36 A 3.05 A apart
Temperature
Temperature coefficient -0.290 %/°C -0.340 %/°C +0.050 %/°C for HiS-T640NJ
Mechanical
Dimensions 2465x1134x30 mm 1719x1140x35 mm 2465x1134x30 mm vs 1719x1140x35 mm
Module area 2.795 m² 1.960 m² 0.836 m² apart
Weight 34.7 kg 22.0 kg -12.7 kg for HIE-S400VG
Weight per kWp 54.2 kg/kWp 55.0 kg/kWp Effectively the same
Warranty and degradation
Product warranty 12 yrs 25 yrs +13 yrs for HIE-S400VG
Performance warranty 30 yrs 25 yrs +5 yrs for HiS-T640NJ
Annual degradation 0.40 %/yr 0.55 %/yr -0.15 %/yr for HiS-T640NJ
Technology
Cell technology TOPCon PERC TOPCon vs PERC
Cell type Monocrystalline Monocrystalline Same
Cell count 156 - Not published by Hyundai
Bifacial Yes No Yes vs No
04

Against the whole database

14,129 panels
Efficiency
#2,412 vs #11,680
HiS-T640NJ leads by 9,268 places
Power density
#2,443 vs #11,678
HiS-T640NJ leads by 9,235 places
Heat behaviour
#2,220 vs #8,846
HiS-T640NJ leads by 6,626 places
Weight
#8,527 vs #9,445
HiS-T640NJ leads by 918 places
Warranty
#21 vs #9,912
HiS-T640NJ leads by 9,891 places
Overall
#2,117 vs #10,832
HiS-T640NJ leads by 8,715 places
05

More useful comparisons

Open the full database
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
Same series, other bin
Hyundai HIE-S400VG vs Hyundai HIE-S410VG
3 differences, the largest is module efficiency
Same series, other bin
Hyundai HIE-S400VG vs Hyundai HIE-S405VG
One difference: module efficiency
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Hyundai HIE-S400VG vs Hyundai HIE-S395VG
One difference: module efficiency
Same series, other bin
Hyundai HIE-S400VG vs Hyundai HIE-S390VG
3 differences, the largest is module efficiency
06

Written summary

07

Questions about this pairing

Which panel is better: Hyundai HiS-T640NJ or Hyundai HIE-S400VG?
According to our database: Hyundai HiS-T640NJ has higher module efficiency (22.90% vs 20.40%); 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 HiS-T640NJ and Hyundai HIE-S400VG?
Hyundai HiS-T640NJ has a module efficiency of 22.90%, while Hyundai HIE-S400VG is 20.40%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Hyundai HiS-T640NJ use vs Hyundai HIE-S400VG?
Hyundai HiS-T640NJ uses TOPCon cells; Hyundai HIE-S400VG 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 Hyundai HiS-T640NJ and Hyundai HIE-S400VG?
Hyundai HiS-T640NJ has a 30 years power warranty; Hyundai HIE-S400VG has a 25 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 HiS-T640NJ and Hyundai HIE-S400VG bifacial panels?
Hyundai HiS-T640NJ is bifacial (captures light from both faces); Hyundai HIE-S400VG 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.