--- title: "Tongwei THC G12-66 Bifacial vs Tongwei TNC M10-78 Bifacial - Solar Panel Comparison | ComparePV" description: "Compare Tongwei THC 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-thc-g12-66-bifacial/tongwei-tnc-m10-78-bifacial" updated: 2026-09-11 --- # Tongwei THC G12-66 Bifacial vs Tongwei TNC M10-78 Bifacial THC G12-66 Bifacial leads on the differences that matter The largest is module efficiency: 1.10 pp more efficient. 4 of 17 comparable parameters are identical, with 2 more left out because at least one datasheet does not publish them. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Tongwei THC G12-66 Bifacial](https://comparepv.com/panel/tongwei-thc-g12-66-bifacial) | [Tongwei TNC M10-78 Bifacial](https://comparepv.com/panel/tongwei-tnc-m10-78-bifacial) | | Manufacturer | Tongwei | Tongwei | | Power | 740 Wp | 635 Wp | | Efficiency | 23.80 % | 22.70 % | | Technology | TOPCon | TOPCon | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | THC G12-66 Bifacial | TNC M10-78 Bifacial | Difference | | --- | --- | --- | --- | | Module efficiency | 23.80 % | 22.70 % | +1.10 pp for THC G12-66 Bifacial | | Rated power | 740 Wp | 635 Wp | +105 W for THC G12-66 Bifacial | | Power density | 238.2 Wp/m² | 227.2 Wp/m² | +11.1 Wp/m² for THC G12-66 Bifacial | | Weight | 37.0 kg | 33.8 kg | -3.2 kg for TNC M10-78 Bifacial | | Product warranty | 15 yrs | 12 yrs | +3 yrs for THC G12-66 Bifacial | | Open-circuit voltage | 50.62 V | 57.20 V | 6.58 V apart | | Short-circuit current | 18.47 A | 13.82 A | 4.65 A apart | | Module area | 3.106 m² | 2.795 m² | 0.311 m² apart | | Weight per kWp | 50.0 kg/kWp | 53.2 kg/kWp | -3.2 kg/kWp for THC G12-66 Bifacial | | Voltage at max power | 42.32 V | 48.05 V | 5.73 V apart | | Current at max power | 17.49 A | 13.22 A | 4.27 A apart | | Bifacial | Yes | No | Yes vs No | | Dimensions | 2384x1303x33 mm | 2465x1134 mm | 2384x1303x33 mm vs 2465x1134 mm | ## Every compared parameter | Parameter | THC G12-66 Bifacial | TNC M10-78 Bifacial | | --- | --- | --- | | Rated power | 740 Wp | 635 Wp | | Module efficiency | 23.80 % | 22.70 % | | Power density | 238.2 Wp/m² | 227.2 Wp/m² | | Open-circuit voltage | 50.62 V | 57.20 V | | Voltage at max power | 42.32 V | 48.05 V | | Short-circuit current | 18.47 A | 13.82 A | | Current at max power | 17.49 A | 13.22 A | | Temperature coefficient | -0.280 %/°C | -0.280 %/°C | | Dimensions | 2384x1303x33 mm | 2465x1134 mm | | Module area | 3.106 m² | 2.795 m² | | Weight | 37.0 kg | 33.8 kg | | Weight per kWp | 50.0 kg/kWp | 53.2 kg/kWp | | Product warranty | 15 yrs | 12 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | - | 0.40 %/yr | | Cell technology | TOPCon | TOPCon | | Cell type | Monocrystalline | Monocrystalline | | Cell count | 132 | - | | Bifacial | Yes | No | ## Thirty-year yield A 1.0% first-year loss then 0.40% a year, assumed for both panels, 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, THC G12-66 Bifacial:** 24,828 kWh - **Cumulative output, TNC M10-78 Bifacial:** 21,306 kWh - **Gap:** 3,522 kWh ## Output when hot | Condition | Cell temperature | THC G12-66 Bifacial | TNC M10-78 Bifacial | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 740 W | 635 W | 100.0% of rated power | | Cool, bright day | 40 °C | 709 W | 608 W | 95.8% of rated power | | Typical summer roof | 55 °C | 678 W | 582 W | 91.6% of rated power | | Hot roof | 70 °C | 647 W | 555 W | 87.4% of rated power | ## Against the whole database | Measure | THC G12-66 Bifacial | TNC M10-78 Bifacial | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #433 | #3,307 | 14,005 | THC G12-66 Bifacial leads by 2,874 places | | Power density | #431 | #3,252 | 14,005 | THC G12-66 Bifacial leads by 2,821 places | | Heat behaviour | #1,309 | #1,309 | 14,005 | Tied - the same position in the database | | Weight | #3,317 | #7,071 | 14,005 | THC G12-66 Bifacial leads by 3,754 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #130 | #2,385 | 14,005 | THC G12-66 Bifacial leads by 2,255 places | ## Questions ### Which panel is better: Tongwei THC G12-66 Bifacial or Tongwei TNC M10-78 Bifacial? According to our database: **Tongwei THC G12-66 Bifacial** has higher module efficiency (**23.80%** vs **22.70%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Tongwei THC G12-66 Bifacial and Tongwei TNC M10-78 Bifacial? **Tongwei THC G12-66 Bifacial** has a module efficiency of **23.80%**, 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 THC G12-66 Bifacial use vs Tongwei TNC M10-78 Bifacial? **Tongwei THC 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 THC G12-66 Bifacial and Tongwei TNC M10-78 Bifacial? **Tongwei THC 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. ### Are Tongwei THC G12-66 Bifacial and Tongwei TNC M10-78 Bifacial bifacial panels? **Tongwei THC G12-66 Bifacial** is bifacial (captures light from both faces); **Tongwei TNC M10-78 Bifacial** is monofacial. Bifacial panels work best on ground mounts or raised structures with a light-coloured surface underneath. ## Related comparisons - [Tongwei THC G12-66 Bifacial vs Tongwei TWMNF-66HD](https://comparepv.com/compare/tongwei-thc-g12-66-bifacial/tongwei-twmnf-66hd) - 6 differences, the largest is module efficiency - [Tongwei THC G12-66 Bifacial vs Tongwei TWMNH-66HS](https://comparepv.com/compare/tongwei-thc-g12-66-bifacial/tongwei-twmnh-66hs) - 11 differences, the largest is module efficiency - [Tongwei THC G12-66 Bifacial vs Tongwei TWMNH-66HD](https://comparepv.com/compare/tongwei-thc-g12-66-bifacial/tongwei-twmnh-66hd) - 11 differences, the largest is module efficiency - [Tongwei THC G12-66 Bifacial vs Tongwei TWMNH-54HD](https://comparepv.com/compare/tongwei-thc-g12-66-bifacial/tongwei-twmnh-54hd) - 11 differences, the largest is module efficiency - [Tongwei THC G12-66 Bifacial vs Tongwei TWMNH-48HC](https://comparepv.com/compare/tongwei-thc-g12-66-bifacial/tongwei-twmnh-48hc) - 11 differences, the largest is module efficiency - [Tongwei TNC M10-78 Bifacial vs Tongwei TNC G12-66 Monofacial](https://comparepv.com/compare/tongwei-tnc-m10-78-bifacial/tongwei-tnc-g12-66-monofacial) - 9 differences, the largest is rated power --- Source: https://comparepv.com/compare/tongwei-thc-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.