Skip to main content
M10-78 Bifacial vs G12-66 Monofacial 9 of 18 identical Swap Change panels

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

TNC M10-78 Bifacial
635 Wp 22.70 % TOPCon
Open panel page Datasheet PDF
VS
TNC G12-66 Monofacial
710 Wp 22.90 % TOPCon
Open panel page Datasheet PDF
The verdict

G12-66 Monofacial leads on the differences that matter

The largest is rated power: 75 W more power. 9 of 18 comparable parameters are identical, with 1 more left out because at least one datasheet does not publish it.

See all 9 differences
How alike are they
9 of 18 comparable
parameters are identical
identical differs not published
01

What actually differs

9 of 18 parameters
Parameter M10-78 Bifacial G12-66 Monofacial Difference
Rated power 635 Wp 710 Wp 75 W more power
Weight 33.8 kg 37.9 kg 4.1 kg lighter
Open-circuit voltage 57.20 V 48.94 V 8.26 V apart
Short-circuit current 13.82 A 18.45 A 4.63 A apart
Module area 2.795 m² 3.106 m² 0.311 m² apart
Module efficiency 22.70 % 22.90 % 0.20 pp more efficient
Voltage at max power 48.05 V 40.69 V 7.36 V apart
Current at max power 13.22 A 17.45 A 4.23 A apart
Dimensions 2465x1134 mm 2384x1303 mm 2465x1134 mm vs 2384x1303 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.
M10-78 Bifacial
21,306 kWh
G12-66 Monofacial
23,822 kWh
Lifetime gap
2,516 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario M10-78 Bifacial G12-66 Monofacial
Standard test conditions 25 °C 100.0% of rated power 635 W 710 W
Cool, bright day 40 °C 95.8% of rated power 608 W 680 W
Typical summer roof 55 °C 91.6% of rated power 582 W 650 W
Hot roof 70 °C 87.4% of rated power 555 W 621 W
03

Full specification

Parameter M10-78 Bifacial G12-66 Monofacial Difference
Power and efficiency
Rated power 635 Wp 710 Wp +75 W for G12-66 Monofacial
Module efficiency 22.70 % 22.90 % +0.20 pp for G12-66 Monofacial
Power density 227.2 Wp/m² 228.6 Wp/m² Effectively the same
Open-circuit voltage 57.20 V 48.94 V 8.26 V apart
Voltage at max power 48.05 V 40.69 V 7.36 V apart
Short-circuit current 13.82 A 18.45 A 4.63 A apart
Current at max power 13.22 A 17.45 A 4.23 A apart
Temperature
Temperature coefficient -0.280 %/°C -0.280 %/°C Same
Mechanical
Dimensions 2465x1134 mm 2384x1303 mm 2465x1134 mm vs 2384x1303 mm
Module area 2.795 m² 3.106 m² 0.311 m² apart
Weight 33.8 kg 37.9 kg -4.1 kg for M10-78 Bifacial
Weight per kWp 53.2 kg/kWp 53.4 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 #2,359
G12-66 Monofacial leads by 948 places
Power density
#3,252 vs #2,474
G12-66 Monofacial leads by 778 places
Heat behaviour
#1,309 vs #1,309
Tied - the same position in the database
Weight
#7,071 vs #7,271
M10-78 Bifacial leads by 200 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#2,385 vs #817
G12-66 Monofacial leads by 1,568 places
05

More useful comparisons

Open the full database
Same series, other bin
Tongwei TNC M10-78 Bifacial vs Tongwei THC G12-66 Bifacial
13 differences, the largest is module efficiency
Same series, other bin
Tongwei TNC M10-78 Bifacial vs Tongwei TWMNF-66HD
12 differences, the largest is rated power
Same series, other bin
Tongwei TNC M10-78 Bifacial vs Tongwei TNC G12-66 Bifacial
8 differences, the largest is rated power
Same series, other bin
Tongwei TNC M10-78 Bifacial vs Tongwei TWMNH-66HS
13 differences, the largest is weight
Same series, other bin
Tongwei TNC M10-78 Bifacial vs Tongwei TWMNH-66HD
12 differences, the largest is weight
Same series, other bin
Tongwei TNC M10-78 Bifacial vs Tongwei TNC G12R-66 Monofacial
9 differences, the largest is open-circuit voltage
06

Written summary

07

Questions about this pairing

Which panel is better: Tongwei TNC M10-78 Bifacial or Tongwei TNC G12-66 Monofacial?
According to our database: Tongwei TNC G12-66 Monofacial has higher module efficiency (22.90% vs 22.70%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Tongwei TNC M10-78 Bifacial and Tongwei TNC G12-66 Monofacial?
Tongwei TNC M10-78 Bifacial has a module efficiency of 22.70%, while Tongwei TNC G12-66 Monofacial is 22.90%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Tongwei TNC M10-78 Bifacial use vs Tongwei TNC G12-66 Monofacial?
Tongwei TNC M10-78 Bifacial uses TOPCon cells; Tongwei TNC G12-66 Monofacial 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 M10-78 Bifacial and Tongwei TNC G12-66 Monofacial?
Tongwei TNC M10-78 Bifacial has a 30 years power warranty; Tongwei TNC G12-66 Monofacial 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.

Shop prices: See 72 Tongwei 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.