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DM645M10T-B78HSW vs DM640M10T-B78HSW 18 of 19 identical Swap Change panels

DMEGC DM645M10T-B78HSW vs DMEGC DM640M10T-B78HSW

DMEGC DM645M10T-B78HSW
DM645M10T-B78HSW
645 Wp 23.10 % TOPCon Bifacial
Open panel page Datasheet PDF
VS
DMEGC DM640M10T-B78HSW
DM640M10T-B78HSW
640 Wp 22.90 % TOPCon Bifacial
Open panel page Datasheet PDF
The verdict

DM645M10T-B78HSW 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 DM645M10T-B78HSW DM640M10T-B78HSW Difference
Module efficiency 23.10 % 22.90 % 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 (-0.290 %/°C), so a warmer roof scales both curves by the same factor: the totals fall together and neither panel gains on the other.
DM645M10T-B78HSW
21,641 kWh
DM640M10T-B78HSW
21,473 kWh
Lifetime gap
168 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario DM645M10T-B78HSW DM640M10T-B78HSW
Standard test conditions 25 °C 100.0% of rated power 645 W 640 W
Cool, bright day 40 °C 95.7% of rated power 617 W 612 W
Typical summer roof 55 °C 91.3% of rated power 589 W 584 W
Hot roof 70 °C 87.0% of rated power 561 W 556 W
03

Full specification

Parameter DM645M10T-B78HSW DM640M10T-B78HSW Difference
Power and efficiency
Rated power 645 Wp 640 Wp Effectively the same
Module efficiency 23.10 % 22.90 % +0.20 pp for DM645M10T-B78HSW
Power density 230.7 Wp/m² 229.0 Wp/m² Effectively the same
Open-circuit voltage 57.90 V 57.70 V Effectively the same
Voltage at max power 48.05 V 47.86 V Effectively the same
Short-circuit current 14.19 A 14.14 A Effectively the same
Current at max power 13.44 A 13.39 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 33.5 kg 33.5 kg Same
Weight per kWp 51.9 kg/kWp 52.3 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
#1,570 vs #2,359
DM645M10T-B78HSW leads by 789 places
Power density
#1,654 vs #2,389
DM645M10T-B78HSW leads by 735 places
Heat behaviour
#2,165 vs #2,165
Tied - the same position in the database
Weight
#5,361 vs #5,829
DM645M10T-B78HSW leads by 468 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#1,491 vs #1,691
DM645M10T-B78HSW leads by 200 places
05

More useful comparisons

Open the full database
Same series, other bin
DMEGC DM645M10T-B78HSW vs DMEGC DM650M10T-B78HSW
One difference: module efficiency
Same series, other bin
DMEGC DM645M10T-B78HSW vs DMEGC DM635M10T-B78HSW
3 differences, the largest is module efficiency
Same series, other bin
DMEGC DM645M10T-B78HSW vs DMEGC DM630M10T-B78HSW
3 differences, the largest is module efficiency
Same series, other bin
DMEGC DM645M10T-B78HSW vs DMEGC DM600M10T-B72HSW
7 differences, the largest is rated power
Same series, other bin
DMEGC DM645M10T-B78HSW vs DMEGC DM595M10T-B72HSW
7 differences, the largest is rated power
Same series, other bin
DMEGC DM645M10T-B78HSW vs DMEGC DM590M10T-B72HSW
8 differences, the largest is rated power
06

Written summary

07

Questions about this pairing

Which panel is better: DMEGC DM645M10T-B78HSW or DMEGC DM640M10T-B78HSW?
According to our database: DMEGC DM645M10T-B78HSW has higher module efficiency (23.10% vs 22.90%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of DMEGC DM645M10T-B78HSW and DMEGC DM640M10T-B78HSW?
DMEGC DM645M10T-B78HSW has a module efficiency of 23.10%, while DMEGC DM640M10T-B78HSW is 22.90%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does DMEGC DM645M10T-B78HSW use vs DMEGC DM640M10T-B78HSW?
DMEGC DM645M10T-B78HSW uses TOPCon cells; DMEGC DM640M10T-B78HSW 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 DMEGC DM645M10T-B78HSW and DMEGC DM640M10T-B78HSW?
DMEGC DM645M10T-B78HSW has a 30 years power warranty; DMEGC DM640M10T-B78HSW 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 DMEGC DM645M10T-B78HSW and DMEGC DM640M10T-B78HSW bifacial panels?
Both DMEGC DM645M10T-B78HSW and DMEGC DM640M10T-B78HSW 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.