--- title: "Trina Solar TSM-NEG21C.20-740 vs Trina Solar TSM-NEG18R.28-475 - Solar Panel Comparison | ComparePV" description: "Compare Trina Solar TSM-NEG21C.20-740 vs Trina Solar TSM-NEG18R.28-475 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-neg21c-20-740/trina-solar-tsm-neg18r-28-475" image: "https://comparepv.com/og/compare/panels/trina-solar-co-ltd-tsm-neg21c-20-740/trina-solar-tsm-neg18r-28-475.png" updated: 2026-09-11 --- # Trina Solar TSM-NEG21C.20-740 vs Trina Solar TSM-NEG18R.28-475 NEG21C.20-740 leads on the differences that matter The largest is module efficiency: 2.40 pp more efficient. 5 of 19 comparable parameters are identical. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Trina Solar TSM-NEG21C.20-740](https://comparepv.com/panel/trina-solar-co-ltd-tsm-neg21c-20-740) | [Trina Solar TSM-NEG18R.28-475](https://comparepv.com/panel/trina-solar-tsm-neg18r-28-475) | | Manufacturer | Trina Solar | Trina Solar | | Power | 740 Wp | 475 Wp | | Efficiency | 23.80 % | 21.40 % | | Technology | TOPCon | TOPCon | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | NEG21C.20-740 | NEG18R.28-475 | Difference | | --- | --- | --- | --- | | Module efficiency | 23.80 % | 21.40 % | +2.40 pp for NEG21C.20-740 | | Rated power | 740 Wp | 475 Wp | +265 W for NEG21C.20-740 | | Power density | 238.2 Wp/m² | 213.6 Wp/m² | +24.6 Wp/m² for NEG21C.20-740 | | Weight | 38.3 kg | 23.5 kg | -14.8 kg for NEG18R.28-475 | | Product warranty | 12 yrs | 15 yrs | +3 yrs for NEG18R.28-475 | | Open-circuit voltage | 50.30 V | 39.00 V | 11.30 V apart | | Short-circuit current | 18.66 A | 15.68 A | 2.98 A apart | | Module area | 3.106 m² | 2.224 m² | 0.883 m² apart | | Voltage at max power | 42.10 V | 32.30 V | 9.80 V apart | | Current at max power | 17.58 A | 14.72 A | 2.86 A apart | | Cell count | 132 | 108 | 24 cells apart | | Weight per kWp | 51.8 kg/kWp | 49.5 kg/kWp | -2.3 kg/kWp for NEG18R.28-475 | | Bifacial | Yes | No | Yes vs No | | Dimensions | 2384x1303x33 mm | 1961x1134x30 mm | 2384x1303x33 mm vs 1961x1134x30 mm | ## Every compared parameter | Parameter | NEG21C.20-740 | NEG18R.28-475 | | --- | --- | --- | | Rated power | 740 Wp | 475 Wp | | Module efficiency | 23.80 % | 21.40 % | | Power density | 238.2 Wp/m² | 213.6 Wp/m² | | Open-circuit voltage | 50.30 V | 39.00 V | | Voltage at max power | 42.10 V | 32.30 V | | Short-circuit current | 18.66 A | 15.68 A | | Current at max power | 17.58 A | 14.72 A | | Temperature coefficient | -0.290 %/°C | -0.290 %/°C | | Dimensions | 2384x1303x33 mm | 1961x1134x30 mm | | Module area | 3.106 m² | 2.224 m² | | Weight | 38.3 kg | 23.5 kg | | Weight per kWp | 51.8 kg/kWp | 49.5 kg/kWp | | Product warranty | 12 yrs | 15 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 | 132 | 108 | | Bifacial | Yes | No | ## Thirty-year yield Each panel's own declared degradation curve, at 1,200 kWh/kWp a year Same temp coeff. for both panels (-0.290 %/°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, NEG21C.20-740:** 24,828 kWh - **Cumulative output, NEG18R.28-475:** 15,937 kWh - **Gap:** 8,891 kWh ## Output when hot | Condition | Cell temperature | NEG21C.20-740 | NEG18R.28-475 | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 740 W | 475 W | 100.0% of rated power | | Cool, bright day | 40 °C | 708 W | 454 W | 95.7% of rated power | | Typical summer roof | 55 °C | 676 W | 434 W | 91.3% of rated power | | Hot roof | 70 °C | 643 W | 413 W | 87.0% of rated power | ## Against the whole database | Measure | NEG21C.20-740 | NEG18R.28-475 | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #462 | #8,388 | 14,129 | NEG21C.20-740 leads by 7,926 places | | Power density | #460 | #8,476 | 14,129 | NEG21C.20-740 leads by 8,016 places | | Heat behaviour | #2,220 | #2,220 | 14,129 | Tied - the same position in the database | | Weight | #5,156 | #3,013 | 14,129 | NEG18R.28-475 leads by 2,143 places | | Warranty | #21 | #21 | 14,129 | Tied - the same position in the database | | Overall | #185 | #8,934 | 14,129 | NEG21C.20-740 leads by 8,749 places | ## Questions ### Which panel is better: Trina Solar TSM-NEG21C.20-740 or Trina Solar TSM-NEG18R.28-475? According to our database: **Trina Solar TSM-NEG21C.20-740** has higher module efficiency (**23.80%** vs **21.40%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Trina Solar TSM-NEG21C.20-740 and Trina Solar TSM-NEG18R.28-475? **Trina Solar TSM-NEG21C.20-740** has a module efficiency of **23.80%**, while **Trina Solar TSM-NEG18R.28-475** is **21.40%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Trina Solar TSM-NEG21C.20-740 use vs Trina Solar TSM-NEG18R.28-475? **Trina Solar TSM-NEG21C.20-740** uses **TOPCon** cells; **Trina Solar TSM-NEG18R.28-475** 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-NEG21C.20-740 and Trina Solar TSM-NEG18R.28-475? **Trina Solar TSM-NEG21C.20-740** has a **30 years** power warranty; **Trina Solar TSM-NEG18R.28-475** 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-NEG21C.20-740 and Trina Solar TSM-NEG18R.28-475 bifacial panels? **Trina Solar TSM-NEG21C.20-740** is bifacial (captures light from both faces); **Trina Solar TSM-NEG18R.28-475** is monofacial. Bifacial panels work best on ground mounts or raised structures with a light-coloured surface underneath. ## Related comparisons - [Trina Solar TSM-NEG21C.20-740 vs Trina Solar TSM-NEG21C.20-735](https://comparepv.com/compare/trina-solar-co-ltd-tsm-neg21c-20-740/trina-solar-co-ltd-tsm-neg21c-20-735) - The same specification on paper - [Trina Solar TSM-NEG21C.20-740 vs Trina Solar TSM-NEG21C.20-730](https://comparepv.com/compare/trina-solar-co-ltd-tsm-neg21c-20-740/trina-solar-co-ltd-tsm-neg21c-20-730) - 3 differences, the largest is module efficiency - [Trina Solar TSM-NEG21C.20-740 vs Trina Solar TSM-NEG21C.20-725](https://comparepv.com/compare/trina-solar-co-ltd-tsm-neg21c-20-740/trina-solar-co-ltd-tsm-neg21c-20-725) - 3 differences, the largest is module efficiency - [Trina Solar TSM-NEG21C.20-740 vs Trina Solar TSM-NEG21C.20-720](https://comparepv.com/compare/trina-solar-co-ltd-tsm-neg21c-20-740/trina-solar-co-ltd-tsm-neg21c-20-720) - 3 differences, the largest is module efficiency - [Trina Solar TSM-NEG21C.20-740 vs Trina Solar TSM-NEG21C.20-715](https://comparepv.com/compare/trina-solar-co-ltd-tsm-neg21c-20-740/trina-solar-co-ltd-tsm-neg21c-20-715) - 5 differences, the largest is module efficiency - [Trina Solar TSM-NEG18R.28-475 vs Trina Solar TSM-NEG18R.28-480](https://comparepv.com/compare/trina-solar-tsm-neg18r-28-475/trina-solar-tsm-neg18r-28-480) - One difference: module efficiency --- Source: https://comparepv.com/compare/trina-solar-co-ltd-tsm-neg21c-20-740/trina-solar-tsm-neg18r-28-475 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.