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

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

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

1 640W leads on the differences that matter

The largest is cell technology: TOPCon vs N-type. 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 640W 1-635 Difference
Cell technology TOPCon N-type TOPCon vs N-type
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 640W
21,076 kWh
1-635
20,911 kWh
Lifetime gap
165 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 1 640W 1-635
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 640W 1-635 Difference
Power and efficiency
Rated power 640 Wp 635 Wp Effectively the same
Module efficiency 23.70 % 23.50 % +0.20 pp for 1 640W
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 TOPCon N-type TOPCon vs N-type
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 640W leads by 200 places
Power density
#553 vs #777
1 640W 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 640W leads by 363 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#1,545 vs #1,760
1 640W leads by 215 places
05

More useful comparisons

Open the full database
Same series, other bin
Heckert Solar
Heckert Solar ZEUS 2.1 640W vs Heckert Solar ZEUS 2.1-640
One difference: cell technology
Same series, other bin
Heckert Solar
Heckert Solar ZEUS 2.1 640W vs Heckert Solar ZEUS 2.1 635W
One difference: module efficiency
Same series, other bin
Heckert Solar
Heckert Solar ZEUS 2.1 640W 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 640W 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 640W 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 640W 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 640W or Heckert Solar ZEUS 2.1-635?
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 640W and Heckert Solar ZEUS 2.1-635?
Heckert Solar ZEUS 2.1 640 W has a module efficiency of 23.70%, while Heckert Solar ZEUS 2.1-635 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 640W use vs Heckert Solar ZEUS 2.1-635?
Heckert Solar ZEUS 2.1 640 W uses TOPCon cells; Heckert Solar ZEUS 2.1-635 uses N-type. 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 640W and Heckert Solar ZEUS 2.1-635?
Heckert Solar ZEUS 2.1 640 W has a 30 years power warranty; Heckert Solar ZEUS 2.1-635 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 640W and Heckert Solar ZEUS 2.1-635 bifacial panels?
Both Heckert Solar ZEUS 2.1 640 W and Heckert Solar ZEUS 2.1-635 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.