--- title: "Gokin GK-4-78HGBD-770M vs Gokin GK-4-78HGBD-775M - Solar Panel Comparison | ComparePV" description: "Compare Gokin GK-4-78HGBD-770M vs Gokin GK-4-78HGBD-775M 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-770m/gokin-gk-4-78hgbd-775m" updated: 2026-09-11 --- # Gokin GK-4-78HGBD-770M vs Gokin GK-4-78HGBD-775M Identical on every published parameter All 19 comparable parameters agree. Two records this alike are usually one panel sold under two names, or two bins of the same production line - decide on price and on who you would rather buy from. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Gokin GK-4-78HGBD-770M](https://comparepv.com/panel/gokin-gk-4-78hgbd-770m) | [Gokin GK-4-78HGBD-775M](https://comparepv.com/panel/gokin-gk-4-78hgbd-775m) | | Manufacturer | Gokin | Gokin | | Power | 770 Wp | 775 Wp | | Efficiency | 24.00 % | 24.10 % | | Technology | Back Contact | Back Contact | ## Every compared parameter | Parameter | 770M | 775M | | --- | --- | --- | | Rated power | 770 Wp | 775 Wp | | Module efficiency | 24.00 % | 24.10 % | | Power density | 239.7 Wp/m² | 241.3 Wp/m² | | Open-circuit voltage | 58.72 V | 58.82 V | | Voltage at max power | 48.77 V | 48.87 V | | Short-circuit current | 16.64 A | 16.71 A | | Current at max power | 15.79 A | 15.86 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 | 50.3 kg/kWp | 49.9 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, 770M:** 26,036 kWh - **Cumulative output, 775M:** 26,205 kWh - **Gap:** 169 kWh ## Output when hot | Condition | Cell temperature | 770M | 775M | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 770 W | 775 W | 100.0% of rated power | | Cool, bright day | 40 °C | 740 W | 745 W | 96.1% of rated power | | Typical summer roof | 55 °C | 710 W | 715 W | 92.2% of rated power | | Hot roof | 70 °C | 680 W | 684 W | 88.3% of rated power | ## Against the whole database | Measure | 770M | 775M | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #303 | #219 | 14,005 | 775M leads by 84 places | | Power density | #347 | #227 | 14,005 | 775M leads by 120 places | | Heat behaviour | #511 | #511 | 14,005 | Tied - the same position in the database | | Weight | #3,695 | #3,297 | 14,005 | 775M leads by 398 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #39 | #29 | 14,005 | 775M leads by 10 places | ## Questions ### Which panel is better: Gokin GK-4-78HGBD-770M or Gokin GK-4-78HGBD-775M? According to our database: **Gokin GK-4-78HGBD-775M** has higher module efficiency (**24.10%** vs **24.00%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Gokin GK-4-78HGBD-770M and Gokin GK-4-78HGBD-775M? **Gokin GK-4-78HGBD-770M** has a module efficiency of **24.00%**, while **Gokin GK-4-78HGBD-775M** is **24.10%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Gokin GK-4-78HGBD-770M use vs Gokin GK-4-78HGBD-775M? **Gokin GK-4-78HGBD-770M** uses **Back Contact** cells; **Gokin GK-4-78HGBD-775M** 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-770M and Gokin GK-4-78HGBD-775M? **Gokin GK-4-78HGBD-770M** has a **30 years** power warranty; **Gokin GK-4-78HGBD-775M** 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-770M and Gokin GK-4-78HGBD-775M bifacial panels? Both **Gokin GK-4-78HGBD-770M** and **Gokin GK-4-78HGBD-775M** 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-770M vs Gokin GK-4-78HGBD-780M](https://comparepv.com/compare/gokin-gk-4-78hgbd-770m/gokin-gk-4-78hgbd-780m) - 3 differences, the largest is module efficiency - [Gokin GK-4-78HGBD-770M vs Gokin GK-4-78HGBD-765M](https://comparepv.com/compare/gokin-gk-4-78hgbd-770m/gokin-gk-4-78hgbd-765m) - One difference: module efficiency - [Gokin GK-4-78HGBD-770M vs Gokin GK-4-78HGBD-760M](https://comparepv.com/compare/gokin-gk-4-78hgbd-770m/gokin-gk-4-78hgbd-760m) - 3 differences, the largest is module efficiency - [Gokin GK-4-78HGBD-770M vs Gokin GK-5-60HG-540M](https://comparepv.com/compare/gokin-gk-4-78hgbd-770m/gokin-gk-5-60hg-540m) - 13 differences, the largest is rated power - [Gokin GK-4-78HGBD-770M vs Gokin GK-5-60HG-535M](https://comparepv.com/compare/gokin-gk-4-78hgbd-770m/gokin-gk-5-60hg-535m) - 11 differences, the largest is rated power - [Gokin GK-4-78HGBD-770M vs Gokin GK-5-60HG-530M](https://comparepv.com/compare/gokin-gk-4-78hgbd-770m/gokin-gk-5-60hg-530m) - 11 differences, the largest is rated power --- Source: https://comparepv.com/compare/gokin-gk-4-78hgbd-770m/gokin-gk-4-78hgbd-775m 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.