Skip to main content
635W vs 640W 18 of 19 identical Swap Change panels

Heckert Solar ZEUS 2.1 635W vs Heckert Solar ZEUS 2.1 640W

Heckert Solar
ZEUS 2.1 635W
635 Wp 23.50 % TOPCon Bifacial
Open panel page Datasheet PDF
VS
Heckert Solar
ZEUS 2.1 640W
640 Wp 23.70 % TOPCon Bifacial
Open panel page Datasheet PDF
The verdict

640W leads on the differences that matter

The largest is module efficiency: 0.20 pp more efficient. 18 of 19 comparable parameters are identical.

See the one difference
How alike are they
18 of 19 comparable
parameters are identical
identical differs
01

What actually differs

1 of 19 parameters
Parameter 635W 640W Difference
Module efficiency 23.50 % 23.70 % 0.20 pp more efficient
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 (-0.280 %/°C), so a warmer roof scales both curves by the same factor: the totals fall together and neither panel gains on the other.
635W
20,911 kWh
640W
21,076 kWh
Lifetime gap
165 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 635W 640W
Standard test conditions 25 °C 100.0% of rated power 635 W 640 W
Cool, bright day 40 °C 95.8% of rated power 608 W 613 W
Typical summer roof 55 °C 91.6% of rated power 582 W 586 W
Hot roof 70 °C 87.4% of rated power 555 W 559 W
03

Full specification

Parameter 635W 640W Difference
Power and efficiency
Rated power 635 Wp 640 Wp Effectively the same
Module efficiency 23.50 % 23.70 % +0.20 pp for 640W
Power density 235.1 Wp/m² 236.9 Wp/m² Effectively the same
Open-circuit voltage 49.60 V 49.75 V Effectively the same
Voltage at max power 41.24 V 41.38 V Effectively the same
Short-circuit current 16.26 A 16.33 A Effectively the same
Current at max power 15.40 A 15.47 A Effectively the same
Temperature
Temperature coefficient -0.280 %/°C -0.280 %/°C Same
Mechanical
Dimensions 2382x1134x30 mm 2382x1134x30 mm Same
Module area 2.701 m² 2.701 m² Same
Weight 32.5 kg 32.5 kg Same
Weight per kWp 51.2 kg/kWp 50.8 kg/kWp Effectively the same
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.45 %/yr 0.45 %/yr Same
Technology
Cell technology TOPCon TOPCon Same
Cell type Monocrystalline Monocrystalline Same
Cell count 132 132 Same
Bifacial Yes Yes Same
04

Against the whole database

14,129 panels
Efficiency
#749 vs #549
640W leads by 200 places
Power density
#777 vs #553
640W leads by 224 places
Heat behaviour
#1,347 vs #1,347
Tied - the same position in the database
Weight
#4,581 vs #4,218
640W leads by 363 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#1,760 vs #1,545
640W leads by 215 places
05

More useful comparisons

Open the full database
Same series, other bin
Heckert Solar
Heckert Solar ZEUS 2.1 635W vs Heckert Solar ZEUS 2.1-640
2 differences, the largest is cell technology
Same series, other bin
Heckert Solar
Heckert Solar ZEUS 2.1 635W vs Heckert Solar ZEUS 2.1-635
One difference: cell technology
Same series, other bin
Heckert Solar
Heckert Solar ZEUS 2.1 635W vs Heckert Solar ZEUS 1.2 FullBlack 280W
12 differences, the largest is rated power
Same series, other bin
Heckert Solar
Heckert Solar ZEUS 2.1 635W vs Heckert Solar ZEUS 1.2-280
12 differences, the largest is rated power
Same series, other bin
Heckert Solar
Heckert Solar ZEUS 2.1 635W vs Heckert Solar ZEUS 1.2 FullBlack 275W
14 differences, the largest is rated power
Same series, other bin
Heckert Solar
Heckert Solar ZEUS 2.1 635W vs Heckert Solar ZEUS 1.2-275
14 differences, the largest is rated power
06

Written summary

07

Questions about this pairing

Which panel is better: Heckert Solar ZEUS 2.1 635W or Heckert Solar ZEUS 2.1 640W?
According to our database: Heckert Solar ZEUS 2.1 640 W has higher module efficiency (23.70% vs 23.50%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Heckert Solar ZEUS 2.1 635W and Heckert Solar ZEUS 2.1 640W?
Heckert Solar ZEUS 2.1 635 W has a module efficiency of 23.50%, while Heckert Solar ZEUS 2.1 640 W is 23.70%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Heckert Solar ZEUS 2.1 635W use vs Heckert Solar ZEUS 2.1 640W?
Heckert Solar ZEUS 2.1 635 W uses TOPCon cells; Heckert Solar ZEUS 2.1 640 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 Heckert Solar ZEUS 2.1 635W and Heckert Solar ZEUS 2.1 640W?
Heckert Solar ZEUS 2.1 635 W has a 30 years power warranty; Heckert Solar ZEUS 2.1 640 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 Heckert Solar ZEUS 2.1 635W and Heckert Solar ZEUS 2.1 640W bifacial panels?
Both Heckert Solar ZEUS 2.1 635 W and Heckert Solar ZEUS 2.1 640 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.

Shop prices: See 16 Heckert Solar offers

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.