--- title: "Tongwei TWMHF-66HD725X vs Tongwei TWMHF-66HD740X - Solar Panel Comparison | ComparePV" description: "Compare Tongwei TWMHF-66HD725X vs Tongwei TWMHF-66HD740X side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/tw-solar-twmhf-66hd725x/tw-solar-twmhf-66hd740x" updated: 2026-09-11 --- # Tongwei TWMHF-66HD725X vs Tongwei TWMHF-66HD740X 66HD740X leads on the differences that matter The largest is module efficiency: 0.50 pp more efficient. 16 of 19 comparable parameters are identical. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Tongwei TWMHF-66HD725X](https://comparepv.com/panel/tw-solar-twmhf-66hd725x) | [Tongwei TWMHF-66HD740X](https://comparepv.com/panel/tw-solar-twmhf-66hd740x) | | Manufacturer | Tongwei | Tongwei | | Power | 725 Wp | 740 Wp | | Efficiency | 23.30 % | 23.80 % | | Technology | N-type | N-type | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | 66HD725X | 66HD740X | Difference | | --- | --- | --- | --- | | Module efficiency | 23.30 % | 23.80 % | +0.50 pp for 66HD740X | | Power density | 233.4 Wp/m² | 238.2 Wp/m² | +4.8 Wp/m² for 66HD740X | | Rated power | 725 Wp | 740 Wp | +15 W for 66HD740X | ## Every compared parameter | Parameter | 66HD725X | 66HD740X | | --- | --- | --- | | Rated power | 725 Wp | 740 Wp | | Module efficiency | 23.30 % | 23.80 % | | Power density | 233.4 Wp/m² | 238.2 Wp/m² | | Open-circuit voltage | 50.38 V | 50.62 V | | Voltage at max power | 42.03 V | 42.32 V | | Short-circuit current | 18.18 A | 18.47 A | | Current at max power | 17.25 A | 17.49 A | | Temperature coefficient | -0.240 %/°C | -0.240 %/°C | | Dimensions | 2384x1303x33 mm | 2384x1303x33 mm | | Module area | 3.106 m² | 3.106 m² | | Weight | 37.0 kg | 37.0 kg | | Weight per kWp | 51.0 kg/kWp | 50.0 kg/kWp | | Product warranty | 15 yrs | 15 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.38 %/yr | 0.38 %/yr | | Cell technology | N-type | N-type | | Cell type | Monocrystalline | Monocrystalline | | Cell count | 132 | 132 | | Bifacial | Yes | Yes | ## Thirty-year yield Each panel's own declared degradation curve, at 1,200 kWh/kWp a year Same temp coeff. for both panels (-0.240 %/°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, 66HD725X:** 24,420 kWh - **Cumulative output, 66HD740X:** 24,925 kWh - **Gap:** 505 kWh ## Output when hot | Condition | Cell temperature | 66HD725X | 66HD740X | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 725 W | 740 W | 100.0% of rated power | | Cool, bright day | 40 °C | 699 W | 713 W | 96.4% of rated power | | Typical summer roof | 55 °C | 673 W | 687 W | 92.8% of rated power | | Hot roof | 70 °C | 647 W | 660 W | 89.2% of rated power | ## Against the whole database | Measure | 66HD725X | 66HD740X | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #1,017 | #433 | 14,005 | 66HD740X leads by 584 places | | Power density | #936 | #431 | 14,005 | 66HD740X leads by 505 places | | Heat behaviour | #13 | #13 | 14,005 | Tied - the same position in the database | | Weight | #4,382 | #3,317 | 14,005 | 66HD740X leads by 1,065 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #263 | #130 | 14,005 | 66HD740X leads by 133 places | ## Questions ### Which panel is better: Tongwei TWMHF-66HD725X or Tongwei TWMHF-66HD740X? According to our database: **Tongwei TWMHF-66HD740X** has higher module efficiency (**23.80%** vs **23.30%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Tongwei TWMHF-66HD725X and Tongwei TWMHF-66HD740X? **Tongwei TWMHF-66HD725X** has a module efficiency of **23.30%**, while **Tongwei TWMHF-66HD740X** is **23.80%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Tongwei TWMHF-66HD725X use vs Tongwei TWMHF-66HD740X? **Tongwei TWMHF-66HD725X** uses **N-type** cells; **Tongwei TWMHF-66HD740X** uses **N-type**. 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 TWMHF-66HD725X and Tongwei TWMHF-66HD740X? **Tongwei TWMHF-66HD725X** has a **30 years** power warranty; **Tongwei TWMHF-66HD740X** 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 TWMHF-66HD725X and Tongwei TWMHF-66HD740X bifacial panels? Both **Tongwei TWMHF-66HD725X** and **Tongwei TWMHF-66HD740X** are bifacial - they capture reflected light from the ground, which can add 5**-15%** more annual energy on ground-mount or elevated rooftop installations with a light surface beneath. ## Related comparisons - [Tongwei TWMHF-66HD725X vs Tongwei TWMHF-66HD735X](https://comparepv.com/compare/tw-solar-twmhf-66hd725x/tw-solar-twmhf-66hd735x) - 3 differences, the largest is module efficiency - [Tongwei TWMHF-66HD725X vs Tongwei TWMHF-66HD730X](https://comparepv.com/compare/tw-solar-twmhf-66hd725x/tw-solar-twmhf-66hd730x) - One difference: module efficiency - [Tongwei TWMHF-66HD725X vs Tongwei TWMHF-66HD720X](https://comparepv.com/compare/tw-solar-twmhf-66hd725x/tw-solar-twmhf-66hd720x) - The same specification on paper - [Tongwei TWMHF-66HD725X vs Tongwei TWMHF-66HD715X](https://comparepv.com/compare/tw-solar-twmhf-66hd725x/tw-solar-twmhf-66hd715x) - 3 differences, the largest is module efficiency - [Tongwei TWMHF-66HD725X vs Tongwei TWMNF-66HD750](https://comparepv.com/compare/tw-solar-twmhf-66hd725x/tongwei-solar-twmnf-66hd750) - 8 differences, the largest is module efficiency - [Tongwei TWMHF-66HD725X vs Tongwei TWMNF-66HD745](https://comparepv.com/compare/tw-solar-twmhf-66hd725x/tongwei-solar-twmnf-66hd745) - 8 differences, the largest is temperature coefficient --- Source: https://comparepv.com/compare/tw-solar-twmhf-66hd725x/tw-solar-twmhf-66hd740x 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.