--- title: "Trina Solar TSM-NEG18R.20-515 vs Trina Solar TSM-NEG21C.20 740 - Solar Panel Comparison | ComparePV" description: "Compare Trina Solar TSM-NEG18R.20-515 vs Trina Solar TSM-NEG21C.20 740 side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/trina-solar-co-ltd-tsm-neg18r-20-515/trina-solar-tsm-neg21c-20-740" updated: 2026-09-11 --- # Trina Solar TSM-NEG18R.20-515 vs Trina Solar TSM-NEG21C.20 740 14 differences, and they point both ways The largest is rated power: 225 W more power. 5 of 19 comparable parameters are identical. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Trina Solar TSM-NEG18R.20-515](https://comparepv.com/panel/trina-solar-co-ltd-tsm-neg18r-20-515) | [Trina Solar TSM-NEG21C.20 740](https://comparepv.com/panel/trina-solar-tsm-neg21c-20-740) | | Manufacturer | Trina Solar | Trina Solar | | Power | 515 Wp | 740 Wp | | Efficiency | 23.20 % | 23.80 % | | Technology | TOPCon | TOPCon | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | NEG18R.20-515 | NEG21C.20 740 | Difference | | --- | --- | --- | --- | | Rated power | 515 Wp | 740 Wp | +225 W for NEG21C.20 740 | | Module efficiency | 23.20 % | 23.80 % | +0.60 pp for NEG21C.20 740 | | Weight | 23.5 kg | 38.3 kg | -14.8 kg for NEG18R.20-515 | | Weight per kWp | 45.6 kg/kWp | 51.8 kg/kWp | -6.1 kg/kWp for NEG18R.20-515 | | Product warranty | 15 yrs | 12 yrs | +3 yrs for NEG18R.20-515 | | Power density | 231.6 Wp/m² | 238.2 Wp/m² | +6.6 Wp/m² for NEG21C.20 740 | | Open-circuit voltage | 40.90 V | 50.30 V | 9.40 V apart | | Short-circuit current | 15.96 A | 18.66 A | 2.70 A apart | | Module area | 2.224 m² | 3.106 m² | 0.883 m² apart | | Voltage at max power | 33.90 V | 42.10 V | 8.20 V apart | | Current at max power | 15.20 A | 17.58 A | 2.38 A apart | | Cell count | 108 | 132 | 24 cells apart | | Bifacial | No | Yes | No vs Yes | | Dimensions | 1961x1134x30 mm | 2384x1303x33 mm | 1961x1134x30 mm vs 2384x1303x33 mm | ## Every compared parameter | Parameter | NEG18R.20-515 | NEG21C.20 740 | | --- | --- | --- | | Rated power | 515 Wp | 740 Wp | | Module efficiency | 23.20 % | 23.80 % | | Power density | 231.6 Wp/m² | 238.2 Wp/m² | | Open-circuit voltage | 40.90 V | 50.30 V | | Voltage at max power | 33.90 V | 42.10 V | | Short-circuit current | 15.96 A | 18.66 A | | Current at max power | 15.20 A | 17.58 A | | Temperature coefficient | -0.290 %/°C | -0.290 %/°C | | Dimensions | 1961x1134x30 mm | 2384x1303x33 mm | | Module area | 2.224 m² | 3.106 m² | | Weight | 23.5 kg | 38.3 kg | | Weight per kWp | 45.6 kg/kWp | 51.8 kg/kWp | | Product warranty | 15 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 | 108 | 132 | | Bifacial | No | Yes | ## Thirty-year yield Each panel's own declared degradation curve, at 1,200 kWh/kWp a year Same temp coeff. for both panels (-0.290 %/°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, NEG18R.20-515:** 17,279 kWh - **Cumulative output, NEG21C.20 740:** 24,828 kWh - **Gap:** 7,549 kWh ## Output when hot | Condition | Cell temperature | NEG18R.20-515 | NEG21C.20 740 | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 515 W | 740 W | 100.0% of rated power | | Cool, bright day | 40 °C | 493 W | 708 W | 95.7% of rated power | | Typical summer roof | 55 °C | 470 W | 676 W | 91.3% of rated power | | Hot roof | 70 °C | 448 W | 643 W | 87.0% of rated power | ## Against the whole database | Measure | NEG18R.20-515 | NEG21C.20 740 | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #1,306 | #433 | 14,005 | NEG21C.20 740 leads by 873 places | | Power density | #1,473 | #431 | 14,005 | NEG21C.20 740 leads by 1,042 places | | Heat behaviour | #2,165 | #2,165 | 14,005 | Tied - the same position in the database | | Weight | #789 | #5,125 | 14,005 | NEG18R.20-515 leads by 4,336 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #5,086 | #185 | 14,005 | NEG21C.20 740 leads by 4,901 places | ## Questions ### Which panel is better: Trina Solar TSM-NEG18R.20-515 or Trina Solar TSM-NEG21C.20 740? According to our database: **Trina Solar TSM-NEG21C.20 740** has higher module efficiency (**23.80%** vs **23.20%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Trina Solar TSM-NEG18R.20-515 and Trina Solar TSM-NEG21C.20 740? **Trina Solar TSM-NEG18R.20-515** has a module efficiency of **23.20%**, while **Trina Solar TSM-NEG21C.20 740** is **23.80%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Trina Solar TSM-NEG18R.20-515 use vs Trina Solar TSM-NEG21C.20 740? **Trina Solar TSM-NEG18R.20-515** uses **TOPCon** cells; **Trina Solar TSM-NEG21C.20 740** 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 Trina Solar TSM-NEG18R.20-515 and Trina Solar TSM-NEG21C.20 740? **Trina Solar TSM-NEG18R.20-515** has a **30 years** power warranty; **Trina Solar TSM-NEG21C.20 740** 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 Trina Solar TSM-NEG18R.20-515 and Trina Solar TSM-NEG21C.20 740 bifacial panels? **Trina Solar TSM-NEG21C.20 740** is bifacial (captures light from both faces); **Trina Solar TSM-NEG18R.20-515** is monofacial. Bifacial panels work best on ground mounts or raised structures with a light-coloured surface underneath. ## Related comparisons - [Trina Solar TSM-NEG18R.20-515 vs Trina Solar TSM-NEG18R.20-520](https://comparepv.com/compare/trina-solar-co-ltd-tsm-neg18r-20-515/trina-solar-co-ltd-tsm-neg18r-20-520) - One difference: module efficiency - [Trina Solar TSM-NEG21C.20 740 vs Trina Solar TSM-NEG21C.20Q-760](https://comparepv.com/compare/trina-solar-tsm-neg21c-20-740/trina-solar-tsm-neg21c-20q-760) - 6 differences, the largest is module efficiency - [Trina Solar TSM-NEG21C.20 740 vs Trina Solar TSM-NEG21C.20Q-755](https://comparepv.com/compare/trina-solar-tsm-neg21c-20-740/trina-solar-tsm-neg21c-20q-755) - 6 differences, the largest is temperature coefficient - [Trina Solar TSM-NEG21C.20 740 vs Trina Solar TSM-NEG21C.20Q-750](https://comparepv.com/compare/trina-solar-tsm-neg21c-20-740/trina-solar-tsm-neg21c-20q-750) - 6 differences, the largest is temperature coefficient - [Trina Solar TSM-NEG21C.20 740 vs Trina Solar TSM-NEG21C.20Q-745](https://comparepv.com/compare/trina-solar-tsm-neg21c-20-740/trina-solar-tsm-neg21c-20q-745) - 4 differences, the largest is temperature coefficient - [Trina Solar TSM-NEG21C.20 740 vs Trina Solar TSM-NEG21C.20-740](https://comparepv.com/compare/trina-solar-tsm-neg21c-20-740/trina-solar-co-ltd-tsm-neg21c-20-740) - The same specification on paper --- Source: https://comparepv.com/compare/trina-solar-co-ltd-tsm-neg18r-20-515/trina-solar-tsm-neg21c-20-740 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.