--- title: "Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675 - Solar Panel Comparison | ComparePV" description: "Compare Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675 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-peak-duo-ml-g12s-3-bfg-665/q-cells-q-peak-duo-ml-g12s-3-bfg-675" updated: 2026-09-11 --- # Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675 675 leads on the differences that matter The largest is module efficiency: 0.30 pp more efficient. 15 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 | [Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665](https://comparepv.com/panel/q-cells-q-peak-duo-ml-g12s-3-bfg-665) | [Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675](https://comparepv.com/panel/q-cells-q-peak-duo-ml-g12s-3-bfg-675) | | Manufacturer | Q-Cells | Q-Cells | | Power | 665 Wp | 675 Wp | | Efficiency | 21.40 % | 21.70 % | | Technology | | | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | 665 | 675 | Difference | | --- | --- | --- | --- | | Module efficiency | 21.40 % | 21.70 % | +0.30 pp for 675 | | Power density | 214.1 Wp/m² | 217.3 Wp/m² | +3.2 Wp/m² for 675 | | Rated power | 665 Wp | 675 Wp | +10 W for 675 | ## Every compared parameter | Parameter | 665 | 675 | | --- | --- | --- | | Rated power | 665 Wp | 675 Wp | | Module efficiency | 21.40 % | 21.70 % | | Power density | 214.1 Wp/m² | 217.3 Wp/m² | | Open-circuit voltage | 45.70 V | 45.74 V | | Voltage at max power | 38.11 V | 38.43 V | | Short-circuit current | 18.39 A | 18.45 A | | Current at max power | 17.45 A | 17.56 A | | Temperature coefficient | -0.340 %/°C | -0.340 %/°C | | Dimensions | 2384x1303x35 mm | 2384x1303x35 mm | | Module area | 3.106 m² | 3.106 m² | | Weight | 38.2 kg | 38.2 kg | | Weight per kWp | 57.4 kg/kWp | 56.6 kg/kWp | | Product warranty | 12 yrs | 12 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.45 %/yr | 0.45 %/yr | | Cell technology | - | - | | 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 (-0.340 %/°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, 665:** 21,899 kWh - **Cumulative output, 675:** 22,228 kWh - **Gap:** 329 kWh ## Output when hot | Condition | Cell temperature | 665 | 675 | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 665 W | 675 W | 100.0% of rated power | | Cool, bright day | 40 °C | 631 W | 641 W | 94.9% of rated power | | Typical summer roof | 55 °C | 597 W | 606 W | 89.8% of rated power | | Hot roof | 70 °C | 563 W | 572 W | 84.7% of rated power | ## Against the whole database | Measure | 665 | 675 | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #8,323 | #7,421 | 14,005 | 675 leads by 902 places | | Power density | #8,250 | #7,349 | 14,005 | 675 leads by 901 places | | Heat behaviour | #8,778 | #8,778 | 14,005 | Tied - the same position in the database | | Weight | #11,217 | #10,738 | 14,005 | 675 leads by 479 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #2,833 | #2,198 | 14,005 | 675 leads by 635 places | ## Questions ### Which panel is better: Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 or Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675? According to our database: **Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675** has higher module efficiency (**21.70%** vs **21.40%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675? **Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665** has a module efficiency of **21.40%**, while **Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675** is **21.70%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 use vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675? **Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665** uses Monocrystalline cells; **Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675** uses Monocrystalline. 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.PEAK DUO ML-G12S.3 / BFG 665 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675? **Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665** has a **30 years** power warranty; **Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675** 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.PEAK DUO ML-G12S.3 / BFG 665 and Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675 bifacial panels? Both **Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665** and **Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 675** 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.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 670](https://comparepv.com/compare/q-cells-q-peak-duo-ml-g12s-3-bfg-665/q-cells-q-peak-duo-ml-g12s-3-bfg-670) - One difference: module efficiency - [Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 660](https://comparepv.com/compare/q-cells-q-peak-duo-ml-g12s-3-bfg-665/q-cells-q-peak-duo-ml-g12s-3-bfg-660) - One difference: module efficiency - [Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 655](https://comparepv.com/compare/q-cells-q-peak-duo-ml-g12s-3-bfg-665/q-cells-q-peak-duo-ml-g12s-3-bfg-655) - 3 differences, the largest is module efficiency - [Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 650](https://comparepv.com/compare/q-cells-q-peak-duo-ml-g12s-3-bfg-665/q-cells-q-peak-duo-ml-g12s-3-bfg-650) - 3 differences, the largest is module efficiency - [Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.TRON XL-G2.3 / BFG 645](https://comparepv.com/compare/q-cells-q-peak-duo-ml-g12s-3-bfg-665/q-cells-q-tron-xl-g2-3-bfg-645) - 14 differences, the largest is module efficiency - [Q-Cells Q.PEAK DUO ML-G12S.3 / BFG 665 vs Q-Cells Q.TRON XL-G2.3 / BFG 640](https://comparepv.com/compare/q-cells-q-peak-duo-ml-g12s-3-bfg-665/q-cells-q-tron-xl-g2-3-bfg-640) - 14 differences, the largest is module efficiency --- Source: https://comparepv.com/compare/q-cells-q-peak-duo-ml-g12s-3-bfg-665/q-cells-q-peak-duo-ml-g12s-3-bfg-675 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.