--- title: "GCL GCL-M12/66H 680 Solar Panel: Specs & Datasheet | ComparePV" description: "GCL GCL-M12/66H 680 solar panel. Specs: 21.90% efficiency, Monocrystalline cells, dimensions, warranty and temperature coefficient." source: "https://comparepv.com/panel/gcl-gcl-m12-66h-680" image: "https://comparepv.com/og/panel/gcl-gcl-m12-66h-680.png" updated: 2026-09-11 --- # GCL GCL-M12/66H 680 Efficiency leader, weak in heat 320 panels in the segment PERC 650-700 W ## Identity - **Manufacturer:** GCL - **Model:** GCL-M12/66H 680 - **Series:** M12/66H - **Rated power:** 680 W - **Cell technology:** PERC ## How it compares Compared against segment PERC 650-700 W (320 panels). | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Power (Wp) | 680 W | 660 W | Strong - top 1% | | | Module efficiency | 21.90% | 21.25% | Strong - top 1% | 6,847 | | Power density | 218.9 | 212.5 | Strong - top 1% | 6,868 | | Temperature coefficient | -0.350 | -0.340 | Weak - bottom 10% | 10,489 | | Weight (kg) | 34.2 kg | 34.5 kg | Strong - top 19% | | | Performance warranty | 25 yrs | 30 yrs | Weak - bottom 21% | 9,912 | ### Full peer table | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Module efficiency | 21.90% | 21.25% | Strong - top 1% | 6,847 | | Power density | 218.9 | 212.5 | Strong - top 1% | 6,868 | | Temperature coefficient | -0.350 | -0.340 | Weak - bottom 10% | 10,489 | | Weight per kWp | 50.3 | 52.3 | Strong - top 19% | 3,721 | | Performance warranty | 25 yrs | 30 yrs | Weak - bottom 21% | 9,912 | ### Strengths - **21.90% module efficiency** - Top 1% of the PERC 650-700 W segment, against a median of 21.25%. Ranked 6,847th in the whole database. - **218.9 watts per square metre** - Top 1% of the PERC 650-700 W segment, against a median of 212.5. Ranked 6,868th in the whole database. - **50.3 kg per kWp** - Top 19% of the PERC 650-700 W segment, against a median of 52.3. ### Watch out for - **-0.350 %/°C temperature coefficient** - Bottom 10% of the PERC 650-700 W segment, against a median of -0.340. - **25 year performance warranty** - Bottom 21% of the PERC 650-700 W segment, against a median of 30 yrs. - **Best for:** Commercial and utility-scale. - **Not ideal for:** Hot climates and owners who want a long output guarantee. ## Specification ### Electrical - **Rated power (Pmax):** 680 W - **Efficiency:** 21.90 % - **Voltage at Pmax (Vmp):** 38.60 V - **Current at Pmax (Imp):** 17.62 A - **Open-circuit voltage (Voc):** 46.40 V - **Short-circuit current (Isc):** 18.75 A - **Max system voltage:** 1500 V ### Temperature - **Temperature coefficient of Pmax:** -0.350 %/degC - **Temperature coefficient of Voc:** -0.280 %/degC - **Temperature coefficient of Isc:** 0.050 %/degC - **NOCT:** 45 degC ### Cell and construction - **Cell type:** Monocrystalline - **Cell technology:** PERC - **Cell count:** 132 ### Physical - **Length:** 2384 mm - **Width:** 1303 mm - **Thickness:** 35 mm - **Weight:** 34.2 kg - **Area:** 3.11 m2 - **Power density:** 218.9 Wp/m2 ### Warranty and degradation - **Product warranty:** 12 years - **Performance warranty:** 25 years - **Output guaranteed at end of warranty:** 84.8 % - **First-year degradation:** 2.00 % - **Annual degradation:** 0.55 % - **Output after 30 years:** 558 W ## Rank in the whole catalogue | Measure | Position | | --- | --- | | Efficiency | 6847 of 14129 | | Power density | 6868 of 14129 | | Temperature coefficient | 10489 of 14129 | | Weight | 3721 of 14129 | | Warranty | 9912 of 14129 | ## Pros - **BNEF Tier-1 Manufacturer - Full Bankability** - GCL-SI has maintained continuous Tier-1 status on the Bloomberg NEF list for multiple years (confirmed under the BNEF March 2026 methodology), enabling project financing via non-recourse debt and satisfying the due diligence requirements of most infrastructure funds. - **M12 (210 mm) Cells + Multi-Busbar Reduce BoS Costs** - The 210 mm cell format delivers 660-680 W per module, requiring fewer racking structures and DC cables compared to conventional 400-500 W modules, directly lowering the Balance of System (BoS) cost per kWp. The multi-busbar architecture shortens current-flow paths and reduces resistive losses. - **Verified Environmental Durability Certifications** - Modules have passed salt mist (IEC 61701), ammonia corrosion (IEC 62716), and sand blowing (DIN EN 60068-2-68) tests, making them suitable for coastal, agricultural, and industrial installations and confirming readiness for long-term PPA agreements. - **Module Efficiency of 21.2-21.9% - Competitive with P-Type PERC Peers** - Module efficiency is comparable to direct competitors in the P-type PERC 210 mm segment: SpolarPV SPV680-TG12-132BD and Solaria SPVxxx-TG12-132BD reach 21.92%, indicating that the GCL M12/66H is in line with the segment median and delivers similar power density per m². - **Resistance to PID and Microcracks** - The manufacturer declares high resistance to Potential-Induced Degradation (PID) through the selection of encapsulant materials and an automated production line certified to ISO 9001/14001/45001, reducing the risk of premature degradation over the 25-year power output warranty horizon. ## Cons - **P-Type PERC Technology - Older Generation** - In 2025-2026, the utility-scale market is migrating to N-type TOPCon and ABC. The direct peer AIKO Comet 3N72 (ABC N-type) achieves 25.2% efficiency versus 21.9% for the GCL M12/66H - a 3.3 percentage-point gap translating to approximately 15% more module area required to achieve the same plant output. Additionally, PERC exhibits a higher Light-Induced Degradation (LID) rate compared to N-type technologies. - **Monofacial Design - A Limitation for Ground-Mount Projects** - The M12/66H series is monofacial (is\_bifacial: false), whereas in the ground-mount segment for plants above 1 MWp, bifacial modules have become the de facto standard, generating 5-20% additional energy from ground-reflected irradiance depending on surface albedo. The absence of bifaciality reduces annual energy yield and project IRR. - **12-Year Product Warranty - Below the Rising Industry Standard** - The product warranty is 12 years, while leading Tier-1 manufacturers (Jinko Tiger Neo, LONGi Hi-MO 7) have moved to a 15-year standard for commercial modules. In the context of 25-year PPAs or project debt financing, a shorter product warranty period may require additional legal protections or dedicated reserves in the financial model. ## About this series The GCL M12/66H photovoltaic module series redefines performance standards in the commercial sector, based on advanced silicon cells with an impressive 210 mm format. The use of **M12-type large-area cell technology** allows for achieving unprecedented power density, which directly translates into a significant reduction in BOS system costs and a smaller number of required mounting structures. Thanks to the use of a **modern Multi-Busbar (MBB) system**, these panels guarantee a significantly shorter current flow path, which effectively minimizes resistive losses and increases the module's resistance to potential micro-cracks occurring over many years of operation. This solution is primarily dedicated to conscious investors and developers of large farms who strive to maximize energy yields while simultaneously lowering the LCOE ratio. A key differentiator of the series from the competition is its **excellent performance at low solar irradiance**, which guarantees stable electricity production even in less favorable weather conditions. Additionally, the precisely designed structure ensures **increased mechanical strength against extreme wind pressure and snow loads**, which is crucial for the long-term safety of the installation in the Polish climate zone. Choosing GCL M12/66H is a strategic investment in technology that optimizes every square meter of available roof or ground space. ## Notable figures - Efficiency of 21.9% is 0.6pp above the \*\*PERC 650-700W\*\* median (21.2%) - At 218.9 W/m² power density, this panel generates 6.4 W/m² more per unit area than \*\*PERC 650-700W\*\* median (212.5 W/m²) - At -0.35%/°C, hot weather performance is typical for \*\*PERC 650-700W\*\* panels - In the top 48% for efficiency among all PERC panels ## Questions ### Is the GCL M12/66H series still available for purchase? The GCL M12/66H series has been discontinued and is no longer actively offered by the manufacturer. Any remaining availability in Poland is limited exclusively to residual stock held by distributors. If you are looking for comparable performance within GCL's current lineup, it is worth considering newer series based on next-generation M12 cells, such as the GCL NT12/66H, which offers power outputs of up to 700 W. ### What warranty applies to the GCL M12/66H photovoltaic panels? The manufacturer provides a 12-year product warranty covering material and workmanship defects, along with a 25-year linear power output warranty. After 25 years of operation, the module should retain at least 84.8% of its nominal output power. These terms are typical for a Tier 1 manufacturer, although newer series on the market increasingly offer an extended product warranty of up to 15 years. ### What is the MBB technology used in the GCL M12/66H and what does it mean in practice? MBB (Multi-Busbar) is a system of multiple thin conductors replacing the conventional 3-5 thick busbars. In practice, this means a shorter current path, which reduces resistive losses and improves the overall module efficiency. A key benefit for the system owner is also greater resistance to cell microcracks, which can occur during transportation or under prolonged snow loading. ### How much does the GCL M12/66H panel weigh and is it suitable for a standard industrial rooftop? The module weighs approximately 34.2 kg and has dimensions of 2384 × 1303 × 35 mm. These are typical dimensions for the 132-cell M12 (210 mm) format and characteristic of panels in the 640-680 W class. Modules of this size and weight are intended primarily for large-area industrial rooftops and ground-mounted systems; a structural load-bearing assessment of the roof must always be carried out prior to installation. ### How do the GCL M12/66H panels perform under overcast conditions and low irradiance levels typical of Poland? Thanks to the large-area M12 PERC cells and MBB technology, the GCL M12/66H series demonstrates good low-light performance, which is particularly relevant in the Polish climate with its frequent overcast days. The power temperature coefficient is -0.35%/°C, resulting in minimal losses on hot days and stable annual energy yield. ### Is GCL a reliable manufacturer and what does Tier 1 status mean for my installation? GCL (GCL Solar Industries) is one of the world's largest manufacturers of photovoltaic cells and modules, headquartered in China. Tier 1 status, assigned by independent analytical agencies such as BloombergNEF, confirms the manufacturer's high financial and quality credibility. For the system owner, this primarily means easier access to project financing from banks and a reduced risk that the manufacturer will exit the market before the warranty period expires. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/EN-M1266H-H0-23c924aa4b0d.pdf) ## Alternatives | Panel | Power | How it differs | | --- | --- | --- | | [AIKO AIKO-A650-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a650-mae72mw) | 650 W | Cooler, lighter, +3.3 pp | | [AIKO AIKO-A680-MDE72Mw](https://comparepv.com/panel/aiko-aiko-a680-mde72mw) | 680 W | Cooler, lighter, +3.3 pp | | [AIKO AIKO-A675-MDE72Mw](https://comparepv.com/panel/aiko-aiko-a675-mde72mw) | 675 W | Cooler, lighter, +3.1 pp | | [AIKO AIKO-A645-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a645-mae72mw) | 645 W | Cooler, lighter, +3.1 pp | | [AIKO AIKO-A700-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a700-mae78dw) | 700 W | Cooler, +3.1 pp, +5 yr warranty | | [WINAICO WST-675BKX72-A2](https://comparepv.com/panel/winaico-wst-675bkx72-a2) | 675 W | Cooler, +3.1 pp, +5 yr warranty | | [AIKO AIKO-A695-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a695-mae78dw) | 695 W | Cooler, +3.0 pp, +5 yr warranty | | [AIKO AIKO-G670-MCH72Mw](https://comparepv.com/panel/aiko-aiko-g670-mch72mw) | 670 W | Cooler, lighter, +2.9 pp | | [GCL GCL-M12/66GDF-655W](https://comparepv.com/panel/gcl-gcl-m12-66gdf-655w) | 655 W | Heavier, -0.8 pp, +5 yr warranty | | [GCL GCL-M12/66H-660W](https://comparepv.com/panel/gcl-gcl-m12-66h-660w) | 660 W | -20 W, -0.7 pp | | [GCL GCL-M12/66H-665W](https://comparepv.com/panel/gcl-gcl-m12-66h-665w) | 665 W | -15 W, -0.5 pp | | [AIKO AIKO-A805-GRH78Dw](https://comparepv.com/panel/aiko-aiko-a805-grh78dw) | 805 W | +125 W, cooler, +3.2 pp | | [AIKO AIKO-A800-GRH78Dw](https://comparepv.com/panel/aiko-aiko-a800-grh78dw) | 800 W | +120 W, cooler, +3.0 pp | | [AIKO AIKO-A795-GRH78Dw](https://comparepv.com/panel/aiko-aiko-a795-grh78dw) | 795 W | +115 W, cooler, +2.9 pp | | [AIKO AIKO-A790-GRH78Dw](https://comparepv.com/panel/aiko-aiko-a790-grh78dw) | 790 W | +110 W, cooler, +2.7 pp | | [Trina Solar TSM-NEG21C.20Q-760](https://comparepv.com/panel/trina-solar-tsm-neg21c-20q-760) | 760 W | +80 W, cooler, +2.6 pp | --- Source: https://comparepv.com/panel/gcl-gcl-m12-66h-680 Not in this file, on the page: the I-V and temperature curves lifted from the manufacturer's datasheet, a thirty-year output simulator and alternatives filtered by how closely they match these dimensions.