Skip to main content
G12R-66 Monofacial vs M10-78 Bifacial 9 of 18 identical Swap Change panels

Tongwei TNC G12R-66 Monofacial vs Tongwei TNC M10-78 Bifacial

TNC G12R-66 Monofacial
620 Wp 23.00 % TOPCon
Open panel page Datasheet PDF
VS
TNC M10-78 Bifacial
635 Wp 22.70 % TOPCon
Open panel page Datasheet PDF
The verdict

G12R-66 Monofacial leads on the differences that matter

The largest is open-circuit voltage: 8.90 V apart. 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 G12R-66 Monofacial M10-78 Bifacial Difference
Open-circuit voltage 48.30 V 57.20 V 8.90 V apart
Short-circuit current 15.95 A 13.82 A 2.13 A apart
Module area 2.701 m² 2.795 m² 0.094 m² apart
Module efficiency 23.00 % 22.70 % 0.30 pp more efficient
Rated power 620 Wp 635 Wp 15 W more power
Voltage at max power 41.55 V 48.05 V 6.50 V apart
Weight 32.5 kg 33.8 kg 1.3 kg lighter
Current at max power 14.93 A 13.22 A 1.71 A apart
Dimensions 2382x1134 mm 2465x1134 mm 2382x1134 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.
G12R-66 Monofacial
20,802 kWh
M10-78 Bifacial
21,306 kWh
Lifetime gap
504 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario G12R-66 Monofacial M10-78 Bifacial
Standard test conditions 25 °C 100.0% of rated power 620 W 635 W
Cool, bright day 40 °C 95.8% of rated power 594 W 608 W
Typical summer roof 55 °C 91.6% of rated power 568 W 582 W
Hot roof 70 °C 87.4% of rated power 542 W 555 W
03

Full specification

Parameter G12R-66 Monofacial M10-78 Bifacial Difference
Power and efficiency
Rated power 620 Wp 635 Wp +15 W for M10-78 Bifacial
Module efficiency 23.00 % 22.70 % +0.30 pp for G12R-66 Monofacial
Power density 229.5 Wp/m² 227.2 Wp/m² Effectively the same
Open-circuit voltage 48.30 V 57.20 V 8.90 V apart
Voltage at max power 41.55 V 48.05 V 6.50 V apart
Short-circuit current 15.95 A 13.82 A 2.13 A apart
Current at max power 14.93 A 13.22 A 1.71 A apart
Temperature
Temperature coefficient -0.280 %/°C -0.280 %/°C Same
Mechanical
Dimensions 2382x1134 mm 2465x1134 mm 2382x1134 mm vs 2465x1134 mm
Module area 2.701 m² 2.795 m² 0.094 m² apart
Weight 32.5 kg 33.8 kg -1.3 kg for G12R-66 Monofacial
Weight per kWp 52.4 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
#1,919 vs #3,307
G12R-66 Monofacial leads by 1,388 places
Power density
#2,191 vs #3,252
G12R-66 Monofacial leads by 1,061 places
Heat behaviour
#1,309 vs #1,309
Tied - the same position in the database
Weight
#5,893 vs #7,071
G12R-66 Monofacial leads by 1,178 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#2,525 vs #2,385
M10-78 Bifacial leads by 140 places
05

More useful comparisons

Open the full database
Same series, other bin
Tongwei TNC G12R-66 Monofacial vs Tongwei THC G12-66 Bifacial
12 differences, the largest is module efficiency
Same series, other bin
Tongwei TNC G12R-66 Monofacial vs Tongwei TWMNF-66HD
8 differences, the largest is rated power
Same series, other bin
Tongwei TNC G12R-66 Monofacial vs Tongwei TNC G12-66 Monofacial
6 differences, the largest is rated power
Same series, other bin
Tongwei TNC G12R-66 Monofacial vs Tongwei TNC G12-66 Bifacial
8 differences, the largest is rated power
Same series, other bin
Tongwei TNC G12R-66 Monofacial vs Tongwei TWMNH-66HS
5 differences, the largest is weight
Same series, other bin
Tongwei TNC G12R-66 Monofacial vs Tongwei TWMNH-66HD
5 differences, the largest is weight
06

Written summary

07

Questions about this pairing

Which panel is better: Tongwei TNC G12R-66 Monofacial or Tongwei TNC M10-78 Bifacial?
According to our database: Tongwei TNC G12R-66 Monofacial has higher module efficiency (23.00% 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 G12R-66 Monofacial and Tongwei TNC M10-78 Bifacial?
Tongwei TNC G12R-66 Monofacial has a module efficiency of 23.00%, 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 G12R-66 Monofacial use vs Tongwei TNC M10-78 Bifacial?
Tongwei TNC G12R-66 Monofacial 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 G12R-66 Monofacial and Tongwei TNC M10-78 Bifacial?
Tongwei TNC G12R-66 Monofacial 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.

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.