--- title: "Gokin GK-4-78HGBD-775M vs Gokin GK-4-78HGBD-780M - Solar Panel Comparison | ComparePV" description: "Compare Gokin GK-4-78HGBD-775M vs Gokin GK-4-78HGBD-780M side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/gokin-gk-4-78hgbd-775m/gokin-gk-4-78hgbd-780m" updated: 2026-09-11 --- # Gokin GK-4-78HGBD-775M vs Gokin GK-4-78HGBD-780M 780M 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 | [Gokin GK-4-78HGBD-775M](https://comparepv.com/panel/gokin-gk-4-78hgbd-775m) | [Gokin GK-4-78HGBD-780M](https://comparepv.com/panel/gokin-gk-4-78hgbd-780m) | | Manufacturer | Gokin | Gokin | | Power | 775 Wp | 780 Wp | | Efficiency | 24.10 % | 24.30 % | | Technology | Back Contact | Back Contact | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | 775M | 780M | Difference | | --- | --- | --- | --- | | Module efficiency | 24.10 % | 24.30 % | +0.20 pp for 780M | ## Every compared parameter | Parameter | 775M | 780M | | --- | --- | --- | | Rated power | 775 Wp | 780 Wp | | Module efficiency | 24.10 % | 24.30 % | | Power density | 241.3 Wp/m² | 242.8 Wp/m² | | Open-circuit voltage | 58.82 V | 58.92 V | | Voltage at max power | 48.87 V | 48.97 V | | Short-circuit current | 16.71 A | 16.78 A | | Current at max power | 15.86 A | 15.93 A | | Temperature coefficient | -0.260 %/°C | -0.260 %/°C | | Dimensions | 2465x1303x33 mm | 2465x1303x33 mm | | Module area | 3.212 m² | 3.212 m² | | Weight | 38.7 kg | 38.7 kg | | Weight per kWp | 49.9 kg/kWp | 49.6 kg/kWp | | Product warranty | 15 yrs | 15 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.35 %/yr | 0.35 %/yr | | Cell technology | Back Contact | Back Contact | | 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 (-0.260 %/°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, 775M:** 26,205 kWh - **Cumulative output, 780M:** 26,374 kWh - **Gap:** 169 kWh ## Output when hot | Condition | Cell temperature | 775M | 780M | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 775 W | 780 W | 100.0% of rated power | | Cool, bright day | 40 °C | 745 W | 750 W | 96.1% of rated power | | Typical summer roof | 55 °C | 715 W | 719 W | 92.2% of rated power | | Hot roof | 70 °C | 684 W | 689 W | 88.3% of rated power | ## Against the whole database | Measure | 775M | 780M | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #219 | #131 | 14,005 | 780M leads by 88 places | | Power density | #227 | #138 | 14,005 | 780M leads by 89 places | | Heat behaviour | #511 | #511 | 14,005 | Tied - the same position in the database | | Weight | #3,297 | #3,161 | 14,005 | 780M leads by 136 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #29 | #15 | 14,005 | 780M leads by 14 places | ## Questions ### Which panel is better: Gokin GK-4-78HGBD-775M or Gokin GK-4-78HGBD-780M? According to our database: **Gokin GK-4-78HGBD-780M** has higher module efficiency (**24.30%** vs **24.10%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Gokin GK-4-78HGBD-775M and Gokin GK-4-78HGBD-780M? **Gokin GK-4-78HGBD-775M** has a module efficiency of **24.10%**, while **Gokin GK-4-78HGBD-780M** is **24.30%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Gokin GK-4-78HGBD-775M use vs Gokin GK-4-78HGBD-780M? **Gokin GK-4-78HGBD-775M** uses **Back Contact** cells; **Gokin GK-4-78HGBD-780M** uses **Back Contact**. 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 Gokin GK-4-78HGBD-775M and Gokin GK-4-78HGBD-780M? **Gokin GK-4-78HGBD-775M** has a **30 years** power warranty; **Gokin GK-4-78HGBD-780M** 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 Gokin GK-4-78HGBD-775M and Gokin GK-4-78HGBD-780M bifacial panels? Both **Gokin GK-4-78HGBD-775M** and **Gokin GK-4-78HGBD-780M** 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 - [Gokin GK-4-78HGBD-775M vs Gokin GK-4-78HGBD-770M](https://comparepv.com/compare/gokin-gk-4-78hgbd-775m/gokin-gk-4-78hgbd-770m) - The same specification on paper - [Gokin GK-4-78HGBD-775M vs Gokin GK-4-78HGBD-765M](https://comparepv.com/compare/gokin-gk-4-78hgbd-775m/gokin-gk-4-78hgbd-765m) - 3 differences, the largest is module efficiency - [Gokin GK-4-78HGBD-775M vs Gokin GK-4-78HGBD-760M](https://comparepv.com/compare/gokin-gk-4-78hgbd-775m/gokin-gk-4-78hgbd-760m) - 3 differences, the largest is module efficiency - [Gokin GK-4-78HGBD-775M vs Gokin GK-5-60HG-540M](https://comparepv.com/compare/gokin-gk-4-78hgbd-775m/gokin-gk-5-60hg-540m) - 12 differences, the largest is rated power - [Gokin GK-4-78HGBD-775M vs Gokin GK-5-60HG-535M](https://comparepv.com/compare/gokin-gk-4-78hgbd-775m/gokin-gk-5-60hg-535m) - 11 differences, the largest is rated power - [Gokin GK-4-78HGBD-775M vs Gokin GK-5-60HG-530M](https://comparepv.com/compare/gokin-gk-4-78hgbd-775m/gokin-gk-5-60hg-530m) - 12 differences, the largest is rated power --- Source: https://comparepv.com/compare/gokin-gk-4-78hgbd-775m/gokin-gk-4-78hgbd-780m 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.