--- title: "Tongwei TNC G12-66 Bifacial vs Tongwei TNC G12R-66 Monofacial - Solar Panel Comparison | ComparePV" description: "Compare Tongwei TNC G12-66 Bifacial vs Tongwei TNC G12R-66 Monofacial 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-g12r-66-monofacial" updated: 2026-09-11 --- # Tongwei TNC G12-66 Bifacial vs Tongwei TNC G12R-66 Monofacial 8 differences, and they point both ways The largest is rated power: 85 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 G12R-66 Monofacial](https://comparepv.com/panel/tongwei-tnc-g12r-66-monofacial) | | Manufacturer | Tongwei | Tongwei | | Power | 705 Wp | 620 Wp | | Efficiency | 22.70 % | 23.00 % | | Technology | TOPCon | TOPCon | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | G12-66 Bifacial | G12R-66 Monofacial | Difference | | --- | --- | --- | --- | | Rated power | 705 Wp | 620 Wp | +85 W for G12-66 Bifacial | | Weight | 37.9 kg | 32.5 kg | -5.4 kg for G12R-66 Monofacial | | Short-circuit current | 18.40 A | 15.95 A | 2.45 A apart | | Module area | 3.106 m² | 2.701 m² | 0.405 m² apart | | Module efficiency | 22.70 % | 23.00 % | +0.30 pp for G12R-66 Monofacial | | Current at max power | 17.40 A | 14.93 A | 2.47 A apart | | Dimensions | 2384x1303 mm | 2382x1134 mm | 2384x1303 mm vs 2382x1134 mm | | Voltage at max power | 40.52 V | 41.55 V | 1.03 V apart | ## Every compared parameter | Parameter | G12-66 Bifacial | G12R-66 Monofacial | | --- | --- | --- | | Rated power | 705 Wp | 620 Wp | | Module efficiency | 22.70 % | 23.00 % | | Power density | 227.0 Wp/m² | 229.5 Wp/m² | | Open-circuit voltage | 48.77 V | 48.30 V | | Voltage at max power | 40.52 V | 41.55 V | | Short-circuit current | 18.40 A | 15.95 A | | Current at max power | 17.40 A | 14.93 A | | Temperature coefficient | -0.280 %/°C | -0.280 %/°C | | Dimensions | 2384x1303 mm | 2382x1134 mm | | Module area | 3.106 m² | 2.701 m² | | Weight | 37.9 kg | 32.5 kg | | Weight per kWp | 53.8 kg/kWp | 52.4 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, G12R-66 Monofacial:** 20,802 kWh - **Gap:** 2,852 kWh ## Output when hot | Condition | Cell temperature | G12-66 Bifacial | G12R-66 Monofacial | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 705 W | 620 W | 100.0% of rated power | | Cool, bright day | 40 °C | 675 W | 594 W | 95.8% of rated power | | Typical summer roof | 55 °C | 646 W | 568 W | 91.6% of rated power | | Hot roof | 70 °C | 616 W | 542 W | 87.4% of rated power | ## Against the whole database | Measure | G12-66 Bifacial | G12R-66 Monofacial | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #3,307 | #1,919 | 14,005 | G12R-66 Monofacial leads by 1,388 places | | Power density | #3,361 | #2,191 | 14,005 | G12R-66 Monofacial leads by 1,170 places | | Heat behaviour | #1,309 | #1,309 | 14,005 | Tied - the same position in the database | | Weight | #7,811 | #5,893 | 14,005 | G12R-66 Monofacial leads by 1,918 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #1,007 | #2,525 | 14,005 | G12-66 Bifacial leads by 1,518 places | ## Questions ### Which panel is better: Tongwei TNC G12-66 Bifacial or Tongwei TNC G12R-66 Monofacial? 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 G12-66 Bifacial and Tongwei TNC G12R-66 Monofacial? **Tongwei TNC G12-66 Bifacial** has a module efficiency of **22.70%**, while **Tongwei TNC G12R-66 Monofacial** is **23.00%**. 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 G12R-66 Monofacial? **Tongwei TNC G12-66 Bifacial** uses **TOPCon** cells; **Tongwei TNC G12R-66 Monofacial** 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 G12R-66 Monofacial? **Tongwei TNC G12-66 Bifacial** has a **30 years** power warranty; **Tongwei TNC G12R-66 Monofacial** 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 TNC M10-78 Bifacial](https://comparepv.com/compare/tongwei-tnc-g12-66-bifacial/tongwei-tnc-m10-78-bifacial) - 8 differences, the largest is rated power - [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 --- Source: https://comparepv.com/compare/tongwei-tnc-g12-66-bifacial/tongwei-tnc-g12r-66-monofacial 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.