--- title: "Q-Cells Q.TRON XL-G2.3 / BFG 640 vs Q-Cells Q.TRON XL-G2.3 / BFG 645 - Solar Panel Comparison | ComparePV" description: "Compare Q-Cells Q.TRON XL-G2.3 / BFG 640 vs Q-Cells Q.TRON XL-G2.3 / BFG 645 side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/q-cells-q-tron-xl-g2-3-bfg-640/q-cells-q-tron-xl-g2-3-bfg-645" updated: 2026-09-11 --- # Q-Cells Q.TRON XL-G2.3 / BFG 640 vs Q-Cells Q.TRON XL-G2.3 / BFG 645 645 leads on the differences that matter The largest is module efficiency: 0.20 pp more efficient. 18 of 19 comparable parameters are identical. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Q-Cells Q.TRON XL-G2.3 / BFG 640](https://comparepv.com/panel/q-cells-q-tron-xl-g2-3-bfg-640) | [Q-Cells Q.TRON XL-G2.3 / BFG 645](https://comparepv.com/panel/q-cells-q-tron-xl-g2-3-bfg-645) | | Manufacturer | Q-Cells | Q-Cells | | Power | 640 Wp | 645 Wp | | Efficiency | 22.90 % | 23.10 % | | Technology | N-type | N-type | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | 640 | 645 | Difference | | --- | --- | --- | --- | | Module efficiency | 22.90 % | 23.10 % | +0.20 pp for 645 | ## Every compared parameter | Parameter | 640 | 645 | | --- | --- | --- | | Rated power | 640 Wp | 645 Wp | | Module efficiency | 22.90 % | 23.10 % | | Power density | 229.2 Wp/m² | 231.0 Wp/m² | | Open-circuit voltage | 57.79 V | 58.07 V | | Voltage at max power | 48.28 V | 48.47 V | | Short-circuit current | 13.99 A | 14.05 A | | Current at max power | 13.26 A | 13.31 A | | Temperature coefficient | -0.290 %/°C | -0.290 %/°C | | Dimensions | 2462x1134x35 mm | 2462x1134x35 mm | | Module area | 2.792 m² | 2.792 m² | | Weight | 35.4 kg | 35.4 kg | | Weight per kWp | 55.3 kg/kWp | 54.9 kg/kWp | | Product warranty | 12 yrs | 12 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.33 %/yr | 0.33 %/yr | | Cell technology | N-type | N-type | | Cell type | Monocrystalline | Monocrystalline | | Cell count | 156 | 156 | | 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 (-0.290 %/°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, 640:** 21,592 kWh - **Cumulative output, 645:** 21,761 kWh - **Gap:** 169 kWh ## Output when hot | Condition | Cell temperature | 640 | 645 | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 640 W | 645 W | 100.0% of rated power | | Cool, bright day | 40 °C | 612 W | 617 W | 95.7% of rated power | | Typical summer roof | 55 °C | 584 W | 589 W | 91.3% of rated power | | Hot roof | 70 °C | 556 W | 561 W | 87.0% of rated power | ## Against the whole database | Measure | 640 | 645 | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #2,359 | #1,570 | 14,005 | 645 leads by 789 places | | Power density | #2,368 | #1,629 | 14,005 | 645 leads by 739 places | | Heat behaviour | #2,165 | #2,165 | 14,005 | Tied - the same position in the database | | Weight | #9,773 | #9,271 | 14,005 | 645 leads by 502 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #2,116 | #1,826 | 14,005 | 645 leads by 290 places | ## Questions ### Which panel is better: Q-Cells Q.TRON XL-G2.3 / BFG 640 or Q-Cells Q.TRON XL-G2.3 / BFG 645? According to our database: **Q-Cells Q.TRON XL-G2.3 / BFG 645** has higher module efficiency (**23.10%** vs **22.90%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Q-Cells Q.TRON XL-G2.3 / BFG 640 and Q-Cells Q.TRON XL-G2.3 / BFG 645? **Q-Cells Q.TRON XL-G2.3 / BFG 640** has a module efficiency of **22.90%**, while **Q-Cells Q.TRON XL-G2.3 / BFG 645** is **23.10%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Q-Cells Q.TRON XL-G2.3 / BFG 640 use vs Q-Cells Q.TRON XL-G2.3 / BFG 645? **Q-Cells Q.TRON XL-G2.3 / BFG 640** uses **N-type** cells; **Q-Cells Q.TRON XL-G2.3 / BFG 645** 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 Q-Cells Q.TRON XL-G2.3 / BFG 640 and Q-Cells Q.TRON XL-G2.3 / BFG 645? **Q-Cells Q.TRON XL-G2.3 / BFG 640** has a **30 years** power warranty; **Q-Cells Q.TRON XL-G2.3 / BFG 645** 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 Q-Cells Q.TRON XL-G2.3 / BFG 640 and Q-Cells Q.TRON XL-G2.3 / BFG 645 bifacial panels? Both **Q-Cells Q.TRON XL-G2.3 / BFG 640** and **Q-Cells Q.TRON XL-G2.3 / BFG 645** 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 - [Q-Cells Q.TRON XL-G2.3 / BFG 640 vs Q-Cells Q.TRON XL-G2.3 / BFG 635](https://comparepv.com/compare/q-cells-q-tron-xl-g2-3-bfg-640/hanwha-q-cells-america-inc-q-tron-xl-g2-3-bfg-635) - 2 differences, the largest is temperature coefficient - [Q-Cells Q.TRON XL-G2.3 / BFG 640 vs Q-Cells Q.TRON XL-G2.3 / BFG 630](https://comparepv.com/compare/q-cells-q-tron-xl-g2-3-bfg-640/hanwha-q-cells-america-inc-q-tron-xl-g2-3-bfg-630) - 4 differences, the largest is module efficiency - [Q-Cells Q.TRON XL-G2.3 / BFG 640 vs Q-Cells Q.TRON XL-G2.3 / BFG 625](https://comparepv.com/compare/q-cells-q-tron-xl-g2-3-bfg-640/hanwha-q-cells-america-inc-q-tron-xl-g2-3-bfg-625) - 4 differences, the largest is module efficiency - [Q-Cells Q.TRON XL-G2.3 / BFG 640 vs Q-Cells Q.TRON XL-G2.3 / BFG 620](https://comparepv.com/compare/q-cells-q-tron-xl-g2-3-bfg-640/hanwha-q-cells-america-inc-q-tron-xl-g2-3-bfg-620) - 5 differences, the largest is module efficiency - [Q-Cells Q.TRON XL-G2.3 / BFG 640 vs Q-Cells Q.TRON XL-G2.3 / BFG 615](https://comparepv.com/compare/q-cells-q-tron-xl-g2-3-bfg-640/hanwha-q-cells-america-inc-q-tron-xl-g2-3-bfg-615) - 6 differences, the largest is module efficiency - [Q-Cells Q.TRON XL-G2.3 / BFG 640 vs Q-Cells Q.TRON XL-G2.3 / BFG 610](https://comparepv.com/compare/q-cells-q-tron-xl-g2-3-bfg-640/hanwha-q-cells-america-inc-q-tron-xl-g2-3-bfg-610) - 7 differences, the largest is module efficiency --- Source: https://comparepv.com/compare/q-cells-q-tron-xl-g2-3-bfg-640/q-cells-q-tron-xl-g2-3-bfg-645 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.