--- title: "Tongwei TNC M10-78 Bifacial vs Tongwei TWMNH-66HS - Solar Panel Comparison | ComparePV" description: "Compare Tongwei TNC M10-78 Bifacial vs Tongwei TWMNH-66HS 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-twmnh-66hs" updated: 2026-09-11 --- # Tongwei TNC M10-78 Bifacial vs Tongwei TWMNH-66HS TWMNH-66HS leads on the differences that matter The largest is weight: 4.8 kg lighter. 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 TNC M10-78 Bifacial](https://comparepv.com/panel/tongwei-tnc-m10-78-bifacial) | [Tongwei TWMNH-66HS](https://comparepv.com/panel/tongwei-twmnh-66hs) | | Manufacturer | Tongwei | Tongwei | | Power | 635 Wp | 625 Wp | | Efficiency | 22.70 % | 23.14 % | | Technology | TOPCon | TOPCon | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | TNC M10-78 Bifacial | TWMNH-66HS | Difference | | --- | --- | --- | --- | | Weight | 33.8 kg | 29.0 kg | -4.8 kg for TWMNH-66HS | | Module efficiency | 22.70 % | 23.14 % | +0.44 pp for TWMNH-66HS | | Weight per kWp | 53.2 kg/kWp | 46.4 kg/kWp | -6.8 kg/kWp for TWMNH-66HS | | Product warranty | 12 yrs | 15 yrs | +3 yrs for TWMNH-66HS | | Open-circuit voltage | 57.20 V | 49.25 V | 7.95 V apart | | Short-circuit current | 13.82 A | 16.14 A | 2.32 A apart | | Module area | 2.795 m² | 2.701 m² | 0.094 m² apart | | Power density | 227.2 Wp/m² | 231.4 Wp/m² | +4.2 Wp/m² for TWMNH-66HS | | Rated power | 635 Wp | 625 Wp | +10 W for TNC M10-78 Bifacial | | Voltage at max power | 48.05 V | 40.77 V | 7.28 V apart | | Current at max power | 13.22 A | 15.33 A | 2.11 A apart | | Bifacial | No | Yes | No vs Yes | | Dimensions | 2465x1134 mm | 2382x1134x30 mm | 2465x1134 mm vs 2382x1134x30 mm | ## Every compared parameter | Parameter | TNC M10-78 Bifacial | TWMNH-66HS | | --- | --- | --- | | Rated power | 635 Wp | 625 Wp | | Module efficiency | 22.70 % | 23.14 % | | Power density | 227.2 Wp/m² | 231.4 Wp/m² | | Open-circuit voltage | 57.20 V | 49.25 V | | Voltage at max power | 48.05 V | 40.77 V | | Short-circuit current | 13.82 A | 16.14 A | | Current at max power | 13.22 A | 15.33 A | | Temperature coefficient | -0.280 %/°C | -0.280 %/°C | | Dimensions | 2465x1134 mm | 2382x1134x30 mm | | Module area | 2.795 m² | 2.701 m² | | Weight | 33.8 kg | 29.0 kg | | Weight per kWp | 53.2 kg/kWp | 46.4 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, TWMNH-66HS:** 20,970 kWh - **Gap:** 336 kWh ## Output when hot | Condition | Cell temperature | TNC M10-78 Bifacial | TWMNH-66HS | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 635 W | 625 W | 100.0% of rated power | | Cool, bright day | 40 °C | 608 W | 599 W | 95.8% of rated power | | Typical summer roof | 55 °C | 582 W | 573 W | 91.6% of rated power | | Hot roof | 70 °C | 555 W | 546 W | 87.4% of rated power | ## Against the whole database | Measure | TNC M10-78 Bifacial | TWMNH-66HS | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #3,307 | #1,509 | 14,005 | TWMNH-66HS leads by 1,798 places | | Power density | #3,252 | #1,513 | 14,005 | TWMNH-66HS leads by 1,739 places | | Heat behaviour | #1,309 | #1,309 | 14,005 | Tied - the same position in the database | | Weight | #7,071 | #1,141 | 14,005 | TWMNH-66HS leads by 5,930 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #2,385 | #1,789 | 14,005 | TWMNH-66HS leads by 596 places | ## Questions ### Which panel is better: Tongwei TNC M10-78 Bifacial or Tongwei TWMNH-66HS? According to our database: **Tongwei TWMNH-66HS** has higher module efficiency (**23.14%** 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 TWMNH-66HS? **Tongwei TNC M10-78 Bifacial** has a module efficiency of **22.70%**, while **Tongwei TWMNH-66HS** is **23.14%**. 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 TWMNH-66HS? **Tongwei TNC M10-78 Bifacial** uses **TOPCon** cells; **Tongwei TWMNH-66HS** 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 TWMNH-66HS? **Tongwei TNC M10-78 Bifacial** has a **30 years** power warranty; **Tongwei TWMNH-66HS** 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 TWMNH-66HS bifacial panels? **Tongwei TWMNH-66HS** 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 TWMNF-66HD](https://comparepv.com/compare/tongwei-tnc-m10-78-bifacial/tongwei-twmnf-66hd) - 12 differences, the largest is rated power - [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-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-twmnh-66hs 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.