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BH-635W vs BH 640W 17 of 19 identical Swap Change panels

Astronergy CHSM78N(DG)/F-BH-635W vs Astronergy CHSM78N(DG)/F-BH 640W

CHSM78N(DG)/F-BH-635W
635 Wp 22.70 % TOPCon Bifacial
Open panel page Datasheet PDF
VS
Astronergy CHSM78N(DG)/F-BH 640W
CHSM78N(DG)/F-BH 640W
640 Wp 22.90 % TOPCon Bifacial
Open panel page Datasheet PDF
The verdict

BH 640W leads on the differences that matter

The largest is module efficiency: 0.20 pp more efficient. 17 of 19 comparable parameters are identical.

See all 2 differences
How alike are they
17 of 19 comparable
parameters are identical
identical differs
01

What actually differs

2 of 19 parameters
Parameter BH-635W BH 640W Difference
Module efficiency 22.70 % 22.90 % 0.20 pp more efficient
Voltage at max power 46.62 V 47.86 V 1.24 V 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
Same temp coeff. for both panels (-0.290 %/°C), so a warmer roof scales both curves by the same factor: the totals fall together and neither panel gains on the other.
BH-635W
21,306 kWh
BH 640W
21,473 kWh
Lifetime gap
167 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario BH-635W BH 640W
Standard test conditions 25 °C 100.0% of rated power 635 W 640 W
Cool, bright day 40 °C 95.7% of rated power 607 W 612 W
Typical summer roof 55 °C 91.3% of rated power 580 W 584 W
Hot roof 70 °C 87.0% of rated power 552 W 556 W
03

Full specification

Parameter BH-635W BH 640W Difference
Power and efficiency
Rated power 635 Wp 640 Wp Effectively the same
Module efficiency 22.70 % 22.90 % +0.20 pp for BH 640W
Power density 227.2 Wp/m² 229.0 Wp/m² Effectively the same
Open-circuit voltage 56.41 V 56.88 V Effectively the same
Voltage at max power 46.62 V 47.86 V 1.24 V apart
Short-circuit current 14.27 A 14.14 A Effectively the same
Current at max power 13.62 A 13.37 A Effectively the same
Temperature
Temperature coefficient -0.290 %/°C -0.290 %/°C Same
Mechanical
Dimensions 2465x1134x30 mm 2465x1134x30 mm Same
Module area 2.795 m² 2.795 m² Same
Weight 34.7 kg 34.7 kg Same
Weight per kWp 54.6 kg/kWp 54.2 kg/kWp Effectively the same
Warranty and degradation
Product warranty 15 yrs 15 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.40 %/yr 0.40 %/yr Same
Technology
Cell technology TOPCon TOPCon Same
Cell type Monocrystalline Monocrystalline Same
Cell count 156 156 Same
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#3,307 vs #2,359
BH 640W leads by 948 places
Power density
#3,252 vs #2,389
BH 640W leads by 863 places
Heat behaviour
#2,165 vs #2,165
Tied - the same position in the database
Weight
#9,020 vs #8,447
BH 640W leads by 573 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#1,931 vs #1,704
BH 640W leads by 227 places
05

More useful comparisons

Open the full database
Same series, other bin
Astronergy CHSM78N(DG)/F-BH-635W vs Astronergy CHSM78N(DG)/F-BH 650W
4 differences, the largest is module efficiency
Same series, other bin
Astronergy CHSM78N(DG)/F-BH-635W vs Astronergy CHSM78N(DG)/F-BH-650W
3 differences, the largest is module efficiency
Same series, other bin
Astronergy CHSM78N(DG)/F-BH-635W vs Astronergy CHSM78N(DG)/F-BH 645W
4 differences, the largest is module efficiency
Same series, other bin
Astronergy CHSM78N(DG)/F-BH-635W vs Astronergy CHSM78N(DG)/F-BH-645W
3 differences, the largest is module efficiency
Same series, other bin
Astronergy CHSM78N(DG)/F-BH-635W vs Astronergy CHSM78N(DG)/F-BH-640W
One difference: module efficiency
Same series, other bin
Astronergy CHSM78N(DG)/F-BH-635W vs Astronergy CHSM78N(DG)/F-BH 635W
One difference: voltage at max power
06

Written summary

07

Questions about this pairing

Which panel is better: Astronergy CHSM78N(DG)/F-BH-635W or Astronergy CHSM78N(DG)/F-BH 640W?
According to our database: Astronergy CHSM78N(DG)/F-BH 640 W has higher module efficiency (22.90% vs 22.70%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Astronergy CHSM78N(DG)/F-BH-635W and Astronergy CHSM78N(DG)/F-BH 640W?
Astronergy CHSM78N(DG)/F-BH-635 W has a module efficiency of 22.70%, while Astronergy CHSM78N(DG)/F-BH 640 W is 22.90%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Astronergy CHSM78N(DG)/F-BH-635W use vs Astronergy CHSM78N(DG)/F-BH 640W?
Astronergy CHSM78N(DG)/F-BH-635 W uses TOPCon cells; Astronergy CHSM78N(DG)/F-BH 640 W 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 Astronergy CHSM78N(DG)/F-BH-635W and Astronergy CHSM78N(DG)/F-BH 640W?
Astronergy CHSM78N(DG)/F-BH-635 W has a 30 years power warranty; Astronergy CHSM78N(DG)/F-BH 640 W 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 Astronergy CHSM78N(DG)/F-BH-635W and Astronergy CHSM78N(DG)/F-BH 640W bifacial panels?
Both Astronergy CHSM78N(DG)/F-BH-635 W and Astronergy CHSM78N(DG)/F-BH 640 W 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.