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G12-66 Bifacial vs M10-78 Bifacial 10 of 18 identical Swap Change panels

Tongwei TNC G12-66 Bifacial vs Tongwei TNC M10-78 Bifacial

TNC G12-66 Bifacial
705 Wp 22.70 % TOPCon
Open panel page Datasheet PDF
VS
TNC M10-78 Bifacial
635 Wp 22.70 % TOPCon
Open panel page Datasheet PDF
The verdict

8 differences, and they point both ways

The largest is rated power: 70 W more power. 10 of 18 comparable parameters are identical, with 1 more left out because at least one datasheet does not publish it.

See all 8 differences
How alike are they
10 of 18 comparable
parameters are identical
identical differs not published
01

What actually differs

8 of 18 parameters
Parameter G12-66 Bifacial M10-78 Bifacial Difference
Rated power 705 Wp 635 Wp 70 W more power
Weight 37.9 kg 33.8 kg 4.1 kg lighter
Open-circuit voltage 48.77 V 57.20 V 8.43 V apart
Short-circuit current 18.40 A 13.82 A 4.58 A apart
Module area 3.106 m² 2.795 m² 0.311 m² apart
Voltage at max power 40.52 V 48.05 V 7.53 V apart
Current at max power 17.40 A 13.22 A 4.18 A apart
Dimensions 2384x1303 mm 2465x1134 mm 2384x1303 mm vs 2465x1134 mm
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.
G12-66 Bifacial
23,654 kWh
M10-78 Bifacial
21,306 kWh
Lifetime gap
2,348 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario G12-66 Bifacial M10-78 Bifacial
Standard test conditions 25 °C 100.0% of rated power 705 W 635 W
Cool, bright day 40 °C 95.8% of rated power 675 W 608 W
Typical summer roof 55 °C 91.6% of rated power 646 W 582 W
Hot roof 70 °C 87.4% of rated power 616 W 555 W
03

Full specification

Parameter G12-66 Bifacial M10-78 Bifacial Difference
Power and efficiency
Rated power 705 Wp 635 Wp +70 W for G12-66 Bifacial
Module efficiency 22.70 % 22.70 % Same
Power density 227.0 Wp/m² 227.2 Wp/m² Effectively the same
Open-circuit voltage 48.77 V 57.20 V 8.43 V apart
Voltage at max power 40.52 V 48.05 V 7.53 V apart
Short-circuit current 18.40 A 13.82 A 4.58 A apart
Current at max power 17.40 A 13.22 A 4.18 A apart
Temperature
Temperature coefficient -0.280 %/°C -0.280 %/°C Same
Mechanical
Dimensions 2384x1303 mm 2465x1134 mm 2384x1303 mm vs 2465x1134 mm
Module area 3.106 m² 2.795 m² 0.311 m² apart
Weight 37.9 kg 33.8 kg -4.1 kg for M10-78 Bifacial
Weight per kWp 53.8 kg/kWp 53.2 kg/kWp Effectively the same
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.40 %/yr 0.40 %/yr Same
Technology
Cell technology TOPCon TOPCon Same
Cell type Monocrystalline Monocrystalline Same
Cell count - - Neither datasheet publishes this
Bifacial No No Same
04

Against the whole database

14,005 panels
Efficiency
#3,307 vs #3,307
Tied - the same position in the database
Power density
#3,361 vs #3,252
M10-78 Bifacial leads by 109 places
Heat behaviour
#1,309 vs #1,309
Tied - the same position in the database
Weight
#7,811 vs #7,071
M10-78 Bifacial leads by 740 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#1,007 vs #2,385
G12-66 Bifacial leads by 1,378 places
05

More useful comparisons

Open the full database
Same series, other bin
Tongwei TNC G12-66 Bifacial vs Tongwei THC G12-66 Bifacial
9 differences, the largest is module efficiency
Same series, other bin
Tongwei TNC G12-66 Bifacial vs Tongwei TWMNF-66HD
6 differences, the largest is product warranty
Same series, other bin
Tongwei TNC G12-66 Bifacial vs Tongwei TNC G12-66 Monofacial
One difference: module efficiency
Same series, other bin
Tongwei TNC G12-66 Bifacial vs Tongwei TWMNH-66HS
11 differences, the largest is rated power
Same series, other bin
Tongwei TNC G12-66 Bifacial vs Tongwei TWMNH-66HD
10 differences, the largest is rated power
Same series, other bin
Tongwei TNC G12-66 Bifacial vs Tongwei TNC G12R-66 Monofacial
8 differences, the largest is rated power
06

Written summary

07

Questions about this pairing

Which panel is better: Tongwei TNC G12-66 Bifacial or Tongwei TNC M10-78 Bifacial?
According to our database: both panels are closely matched on key specs - the decision often comes down to price and local availability. See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Tongwei TNC G12-66 Bifacial and Tongwei TNC M10-78 Bifacial?
Tongwei TNC G12-66 Bifacial has a module efficiency of 22.70%, while Tongwei TNC M10-78 Bifacial is 22.70%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Tongwei TNC G12-66 Bifacial use vs Tongwei TNC M10-78 Bifacial?
Tongwei TNC G12-66 Bifacial uses TOPCon cells; Tongwei TNC M10-78 Bifacial 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 Tongwei TNC G12-66 Bifacial and Tongwei TNC M10-78 Bifacial?
Tongwei TNC G12-66 Bifacial has a 30 years power warranty; Tongwei TNC M10-78 Bifacial 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.

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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.