Skip to main content
1-640 vs 1 635W 17 of 19 identical Swap Change panels

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

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

1-640 leads on the differences that matter

The largest is cell technology: N-type vs TOPCon. 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 1-640 1 635W Difference
Cell technology N-type TOPCon N-type vs TOPCon
Module efficiency 23.70 % 23.50 % 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.
1-640
21,076 kWh
1 635W
20,911 kWh
Lifetime gap
165 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 1-640 1 635W
Standard test conditions 25 °C 100.0% of rated power 640 W 635 W
Cool, bright day 40 °C 95.8% of rated power 613 W 608 W
Typical summer roof 55 °C 91.6% of rated power 586 W 582 W
Hot roof 70 °C 87.4% of rated power 559 W 555 W
03

Full specification

Parameter 1-640 1 635W Difference
Power and efficiency
Rated power 640 Wp 635 Wp Effectively the same
Module efficiency 23.70 % 23.50 % +0.20 pp for 1-640
Power density 236.9 Wp/m² 235.1 Wp/m² Effectively the same
Open-circuit voltage 49.75 V 49.60 V Effectively the same
Voltage at max power 41.38 V 41.24 V Effectively the same
Short-circuit current 16.33 A 16.26 A Effectively the same
Current at max power 15.47 A 15.40 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 50.8 kg/kWp 51.2 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 N-type TOPCon N-type vs TOPCon
Cell type Monocrystalline Monocrystalline Same
Cell count 132 132 Same
Bifacial Yes Yes Same
04

Against the whole database

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

More useful comparisons

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

Written summary

07

Questions about this pairing

Which panel is better: Heckert Solar ZEUS 2.1-640 or Heckert Solar ZEUS 2.1 635W?
According to our database: Heckert Solar ZEUS 2.1-640 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 2.1-640 and Heckert Solar ZEUS 2.1 635W?
Heckert Solar ZEUS 2.1-640 has a module efficiency of 23.70%, while Heckert Solar ZEUS 2.1 635 W is 23.50%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Heckert Solar ZEUS 2.1-640 use vs Heckert Solar ZEUS 2.1 635W?
Heckert Solar ZEUS 2.1-640 uses N-type cells; Heckert Solar ZEUS 2.1 635 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 2.1-640 and Heckert Solar ZEUS 2.1 635W?
Heckert Solar ZEUS 2.1-640 has a 30 years power warranty; Heckert Solar ZEUS 2.1 635 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 2.1-640 and Heckert Solar ZEUS 2.1 635W bifacial panels?
Both Heckert Solar ZEUS 2.1-640 and Heckert Solar ZEUS 2.1 635 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.