--- title: "Tongwei TNC M10-78 Bifacial vs Tongwei TWMNF-66HD - Solar Panel Comparison | ComparePV" description: "Compare Tongwei TNC M10-78 Bifacial vs Tongwei TWMNF-66HD 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-m10-78-bifacial/tongwei-twmnf-66hd" updated: 2026-09-11 --- # Tongwei TNC M10-78 Bifacial vs Tongwei TWMNF-66HD TWMNF-66HD leads on the differences that matter The largest is rated power: 80 W more power. 5 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 TNC M10-78 Bifacial](https://comparepv.com/panel/tongwei-tnc-m10-78-bifacial) | [Tongwei TWMNF-66HD](https://comparepv.com/panel/tongwei-twmnf-66hd) | | Manufacturer | Tongwei | Tongwei | | Power | 635 Wp | 715 Wp | | Efficiency | 22.70 % | 23.00 % | | Technology | TOPCon | TOPCon | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | TNC M10-78 Bifacial | TWMNF-66HD | Difference | | --- | --- | --- | --- | | Rated power | 635 Wp | 715 Wp | +80 W for TWMNF-66HD | | Weight | 33.8 kg | 37.9 kg | -4.1 kg for TNC M10-78 Bifacial | | Product warranty | 12 yrs | 15 yrs | +3 yrs for TWMNF-66HD | | Open-circuit voltage | 57.20 V | 49.11 V | 8.09 V apart | | Short-circuit current | 13.82 A | 18.50 A | 4.68 A apart | | Module area | 2.795 m² | 3.106 m² | 0.311 m² apart | | Module efficiency | 22.70 % | 23.00 % | +0.30 pp for TWMNF-66HD | | Power density | 227.2 Wp/m² | 230.2 Wp/m² | +3.0 Wp/m² for TWMNF-66HD | | Voltage at max power | 48.05 V | 40.86 V | 7.19 V apart | | Current at max power | 13.22 A | 17.50 A | 4.28 A apart | | Bifacial | No | Yes | No vs Yes | | Dimensions | 2465x1134 mm | 2384x1303x33 mm | 2465x1134 mm vs 2384x1303x33 mm | ## Every compared parameter | Parameter | TNC M10-78 Bifacial | TWMNF-66HD | | --- | --- | --- | | Rated power | 635 Wp | 715 Wp | | Module efficiency | 22.70 % | 23.00 % | | Power density | 227.2 Wp/m² | 230.2 Wp/m² | | Open-circuit voltage | 57.20 V | 49.11 V | | Voltage at max power | 48.05 V | 40.86 V | | Short-circuit current | 13.82 A | 18.50 A | | Current at max power | 13.22 A | 17.50 A | | Temperature coefficient | -0.280 %/°C | -0.280 %/°C | | Dimensions | 2465x1134 mm | 2384x1303x33 mm | | Module area | 2.795 m² | 3.106 m² | | Weight | 33.8 kg | 37.9 kg | | Weight per kWp | 53.2 kg/kWp | 53.0 kg/kWp | | Product warranty | 12 yrs | 15 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.40 %/yr | - | | Cell technology | TOPCon | TOPCon | | Cell type | Monocrystalline | Monocrystalline | | Cell count | - | 132 | | Bifacial | No | Yes | ## 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, TNC M10-78 Bifacial:** 21,306 kWh - **Cumulative output, TWMNF-66HD:** 23,990 kWh - **Gap:** 2,684 kWh ## Output when hot | Condition | Cell temperature | TNC M10-78 Bifacial | TWMNF-66HD | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 635 W | 715 W | 100.0% of rated power | | Cool, bright day | 40 °C | 608 W | 685 W | 95.8% of rated power | | Typical summer roof | 55 °C | 582 W | 655 W | 91.6% of rated power | | Hot roof | 70 °C | 555 W | 625 W | 87.4% of rated power | ## Against the whole database | Measure | TNC M10-78 Bifacial | TWMNF-66HD | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #3,307 | #1,919 | 14,005 | TWMNF-66HD leads by 1,388 places | | Power density | #3,252 | #2,018 | 14,005 | TWMNF-66HD leads by 1,234 places | | Heat behaviour | #1,309 | #1,309 | 14,005 | Tied - the same position in the database | | Weight | #7,071 | #6,744 | 14,005 | TWMNF-66HD leads by 327 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #2,385 | #450 | 14,005 | TWMNF-66HD leads by 1,935 places | ## Questions ### Which panel is better: Tongwei TNC M10-78 Bifacial or Tongwei TWMNF-66HD? According to our database: **Tongwei TWMNF-66HD** 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 M10-78 Bifacial and Tongwei TWMNF-66HD? **Tongwei TNC M10-78 Bifacial** has a module efficiency of **22.70%**, while **Tongwei TWMNF-66HD** is **23.00%**. 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 TWMNF-66HD? **Tongwei TNC M10-78 Bifacial** uses **TOPCon** cells; **Tongwei TWMNF-66HD** 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 TWMNF-66HD? **Tongwei TNC M10-78 Bifacial** has a **30 years** power warranty; **Tongwei TWMNF-66HD** 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 TNC M10-78 Bifacial and Tongwei TWMNF-66HD bifacial panels? **Tongwei TWMNF-66HD** 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 TNC M10-78 Bifacial vs Tongwei THC G12-66 Bifacial](https://comparepv.com/compare/tongwei-tnc-m10-78-bifacial/tongwei-thc-g12-66-bifacial) - 13 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 - [Tongwei TNC M10-78 Bifacial vs Tongwei TNC G12-66 Bifacial](https://comparepv.com/compare/tongwei-tnc-m10-78-bifacial/tongwei-tnc-g12-66-bifacial) - 8 differences, the largest is rated power - [Tongwei TNC M10-78 Bifacial vs Tongwei TWMNH-66HS](https://comparepv.com/compare/tongwei-tnc-m10-78-bifacial/tongwei-twmnh-66hs) - 13 differences, the largest is weight - [Tongwei TNC M10-78 Bifacial vs Tongwei TWMNH-66HD](https://comparepv.com/compare/tongwei-tnc-m10-78-bifacial/tongwei-twmnh-66hd) - 12 differences, the largest is weight - [Tongwei TNC M10-78 Bifacial vs Tongwei TNC G12R-66 Monofacial](https://comparepv.com/compare/tongwei-tnc-m10-78-bifacial/tongwei-tnc-g12r-66-monofacial) - 9 differences, the largest is open-circuit voltage --- Source: https://comparepv.com/compare/tongwei-tnc-m10-78-bifacial/tongwei-twmnf-66hd 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.