--- title: "Tongwei TNC G12-66 Bifacial vs Tongwei TNC M10-78 Bifacial - Solar Panel Comparison | ComparePV" description: "Compare Tongwei TNC G12-66 Bifacial vs Tongwei TNC M10-78 Bifacial side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/tongwei-tnc-g12-66-bifacial/tongwei-tnc-m10-78-bifacial" updated: 2026-09-11 --- # Tongwei TNC G12-66 Bifacial vs Tongwei TNC M10-78 Bifacial 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. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Tongwei TNC G12-66 Bifacial](https://comparepv.com/panel/tongwei-tnc-g12-66-bifacial) | [Tongwei TNC M10-78 Bifacial](https://comparepv.com/panel/tongwei-tnc-m10-78-bifacial) | | Manufacturer | Tongwei | Tongwei | | Power | 705 Wp | 635 Wp | | Efficiency | 22.70 % | 22.70 % | | Technology | TOPCon | TOPCon | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | G12-66 Bifacial | M10-78 Bifacial | Difference | | --- | --- | --- | --- | | Rated power | 705 Wp | 635 Wp | +70 W for G12-66 Bifacial | | Weight | 37.9 kg | 33.8 kg | -4.1 kg for M10-78 Bifacial | | 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 | ## Every compared parameter | Parameter | G12-66 Bifacial | M10-78 Bifacial | | --- | --- | --- | | Rated power | 705 Wp | 635 Wp | | Module efficiency | 22.70 % | 22.70 % | | Power density | 227.0 Wp/m² | 227.2 Wp/m² | | Open-circuit voltage | 48.77 V | 57.20 V | | Voltage at max power | 40.52 V | 48.05 V | | Short-circuit current | 18.40 A | 13.82 A | | Current at max power | 17.40 A | 13.22 A | | Temperature coefficient | -0.280 %/°C | -0.280 %/°C | | Dimensions | 2384x1303 mm | 2465x1134 mm | | Module area | 3.106 m² | 2.795 m² | | Weight | 37.9 kg | 33.8 kg | | Weight per kWp | 53.8 kg/kWp | 53.2 kg/kWp | | Product warranty | 12 yrs | 12 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.40 %/yr | 0.40 %/yr | | Cell technology | TOPCon | TOPCon | | Cell type | Monocrystalline | Monocrystalline | | Cell count | - | - | | Bifacial | No | No | ## Thirty-year yield 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. - **Cumulative output, G12-66 Bifacial:** 23,654 kWh - **Cumulative output, M10-78 Bifacial:** 21,306 kWh - **Gap:** 2,348 kWh ## Output when hot | Condition | Cell temperature | G12-66 Bifacial | M10-78 Bifacial | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 705 W | 635 W | 100.0% of rated power | | Cool, bright day | 40 °C | 675 W | 608 W | 95.8% of rated power | | Typical summer roof | 55 °C | 646 W | 582 W | 91.6% of rated power | | Hot roof | 70 °C | 616 W | 555 W | 87.4% of rated power | ## Against the whole database | Measure | G12-66 Bifacial | M10-78 Bifacial | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #3,307 | #3,307 | 14,005 | Tied - the same position in the database | | Power density | #3,361 | #3,252 | 14,005 | M10-78 Bifacial leads by 109 places | | Heat behaviour | #1,309 | #1,309 | 14,005 | Tied - the same position in the database | | Weight | #7,811 | #7,071 | 14,005 | M10-78 Bifacial leads by 740 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #1,007 | #2,385 | 14,005 | G12-66 Bifacial leads by 1,378 places | ## Questions ### 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. ## Related comparisons - [Tongwei TNC G12-66 Bifacial vs Tongwei THC G12-66 Bifacial](https://comparepv.com/compare/tongwei-tnc-g12-66-bifacial/tongwei-thc-g12-66-bifacial) - 9 differences, the largest is module efficiency - [Tongwei TNC G12-66 Bifacial vs Tongwei TWMNF-66HD](https://comparepv.com/compare/tongwei-tnc-g12-66-bifacial/tongwei-twmnf-66hd) - 6 differences, the largest is product warranty - [Tongwei TNC G12-66 Bifacial vs Tongwei TNC G12-66 Monofacial](https://comparepv.com/compare/tongwei-tnc-g12-66-bifacial/tongwei-tnc-g12-66-monofacial) - One difference: module efficiency - [Tongwei TNC G12-66 Bifacial vs Tongwei TWMNH-66HS](https://comparepv.com/compare/tongwei-tnc-g12-66-bifacial/tongwei-twmnh-66hs) - 11 differences, the largest is rated power - [Tongwei TNC G12-66 Bifacial vs Tongwei TWMNH-66HD](https://comparepv.com/compare/tongwei-tnc-g12-66-bifacial/tongwei-twmnh-66hd) - 10 differences, the largest is rated power - [Tongwei TNC G12-66 Bifacial vs Tongwei TNC G12R-66 Monofacial](https://comparepv.com/compare/tongwei-tnc-g12-66-bifacial/tongwei-tnc-g12r-66-monofacial) - 8 differences, the largest is rated power --- Source: https://comparepv.com/compare/tongwei-tnc-g12-66-bifacial/tongwei-tnc-m10-78-bifacial Not in this file, on the page: the thirty-year yield curve year by year at a cell temperature you pick and a written summary generated on request.