--- title: "GCL GCL-NT12/66GDF-740 740W Solar Panel - Specs & Review | ComparePV" description: "GCL GCL-NT12/66GDF-740 740W solar panel. Specs: 23.82% efficiency, Monocrystalline cells, dimensions, warranty and temperature coefficient." source: "https://comparepv.com/panel/gcl-gcl-nt12-66gdf-740" updated: 2026-09-11 --- # GCL GCL-NT12/66GDF-740 Efficiency leader, no clear weak spot 420 panels in the segment TOPCon 700-750 W ## Identity - **Manufacturer:** GCL - **Model:** GCL-NT12/66GDF-740 - **Series:** NT12/66GDF - **Rated power:** 740 W - **Cell technology:** TOPCon - **Bifacial:** yes ## How it compares Compared against segment TOPCon 700-750 W (420 panels). | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Power (Wp) | 740 W | 715 W | Strong - top 2% | | | Module efficiency | 23.82% | 23.00% | Strong - top 1% | 418 | | Power density | 238.2 | 230.2 | Strong - top 2% | 431 | | Temperature coefficient | -0.290 | -0.290 | Typical | 2,165 | | Weight (kg) | 38.2 kg | 38.0 kg | Typical | | | Performance warranty | 30 yrs | 30 yrs | Typical | 21 | ### Full peer table | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Module efficiency | 23.82% | 23.00% | Strong - top 1% | 418 | | Power density | 238.2 | 230.2 | Strong - top 2% | 431 | | Temperature coefficient | -0.290 | -0.290 | Typical | 2,165 | | Weight per kWp | 51.6 | 52.9 | Typical | 4,997 | | Performance warranty | 30 yrs | 30 yrs | Typical | 21 | ### Strengths - **23.82% module efficiency** - Top 1% of the TOPCon 700-750 W segment, against a median of 23.00%. Ranked 418th in the whole database. - **238.2 watts per square metre** - Top 2% of the TOPCon 700-750 W segment, against a median of 230.2. Ranked 431st in the whole database. - **Best for:** Utility-scale, commercial and hot-climate. ## Specification ### Electrical - **Rated power (Pmax):** 740 W - **Efficiency:** 23.82 % - **Voltage at Pmax (Vmp):** 41.60 V - **Current at Pmax (Imp):** 17.79 A - **Open-circuit voltage (Voc):** 49.46 V - **Short-circuit current (Isc):** 18.72 A - **Max system voltage:** 1500 V ### Temperature - **Temperature coefficient of Pmax:** -0.290 %/degC - **Temperature coefficient of Voc:** -0.250 %/degC - **Temperature coefficient of Isc:** 0.045 %/degC ### Cell and construction - **Cell type:** Monocrystalline - **Cell technology:** TOPCon - **Cell count:** 132 - **Bifacial:** yes ### Physical - **Length:** 2384 mm - **Width:** 1303 mm - **Thickness:** 33 mm - **Weight:** 38.2 kg - **Area:** 3.11 m2 - **Power density:** 238.2 Wp/m2 ### Warranty and degradation - **Product warranty:** 12 years - **Performance warranty:** 30 years - **Output guaranteed at end of warranty:** 87.4 % - **First-year degradation:** 1.00 % - **Annual degradation:** 0.40 % - **Output after 30 years:** 647 W ## Rank in the whole catalogue | Measure | Position | | --- | --- | | Efficiency | 418 of 14005 | | Power density | 431 of 14005 | | Temperature coefficient | 2165 of 14005 | | Weight | 4997 of 14005 | | Warranty | 21 of 14005 | ## Pros - **N-type TOPCon – Negligible LID Effect** - N-type TOPCon cells exhibit virtually zero Light-Induced Degradation (LID) compared to PERC technology. This translates into meaningfully higher energy yield over the full 30-year system lifetime — particularly critical for utility-scale plants, where a 1–2% difference in annual production has a measurable impact on project IRR. - **Bifacial Double-Glass – Additional Rear-Side Gain** - The dual-glass construction with bifacial cells enables energy generation from irradiance reflected off the ground surface. With a typical bifaciality factor of ~70–75% and a high-albedo substrate (gravel, white membrane), real-world rear-side gains reach 10–30%, directly improving project economics with no increase in mounting costs. - **30-Year Power Warranty (≥87.4% Pmax)** - The manufacturer's datasheet guarantees ≥99% Pmax after Year 1 and ≥87.4% Pmax after Year 30 — on par with JinkoSolar Tiger Neo (87.4% / 30 years) and well above legacy 25-year contracts with degradation floors of ~84.8%. For project-finance transactions, this represents a compelling bankability argument. - **Temperature Coefficient of −0.29%/°C** - The datasheet-confirmed temperature coefficient of −0.29%/°C is significantly better than typical PERC modules (−0.35%/°C) and approaches the upper performance boundary of TOPCon technology. Under Polish summer conditions — where module temperatures can reach ~70°C — this delivers a real-world yield advantage of 1.5–2% over PERC at equivalent STC power ratings. - **BNEF Tier 1 – Bankable Since 2016** - GCL System Integration Technology (GCL-SI) has appeared on the BNEF Tier 1 list continuously since 2016 and meets the updated Q2 2025 criteria (non-recourse financing of six projects ≥10 MW by six different banks). This ensures module eligibility for bank-financed projects and supply chain stability for large-scale solar farms. ## Cons - **12-Year Product Warranty – Below Premium Tier** - The materials and workmanship warranty stands at 12 years, while premium competitors offer substantially more: LONGi Hi-MO X6 – 30 years, REC Alpha Pure-R – 25 years, Huasun – 15 years. For projects with 20-year debt financing, this gap may necessitate additional insurance instruments or warranty escrow arrangements, increasing overall transaction costs. - **210 mm Format – Impractical Outside Utility-Scale** - The module dimensions of 2384×1303×35 mm and the weight typical of 132-cell 210 mm modules (~35–40 kg) require reinforced racking systems and specialized logistics. The series is optimized for ground-mounted plants and large commercial installations; deploying it on standard residential pitched rooftops is impractical and may generate additional structural costs. ## About this series Photovoltaic panels from the GCL NT12/66GDF series redefine performance standards thanks to the use of innovative **N-type TOPCon** cells, which effectively eliminate negative power degradation phenomena over time. The construction based on **bifacial double-glass** technology ensures that these modules not only generate energy from direct radiation but also effectively utilize light reflected from the ground, significantly increasing investment profitability in challenging lighting conditions. The use of large silicon wafers in the **Large-format 210mm** format allows for the construction of higher-power systems with fewer mounting components, which realistically reduces the cost of the entire installation. This series is primarily designed for large-scale farms and major commercial projects, where durability and resistance to external factors are key. What distinguishes these panels from the competition is an **excellent temperature coefficient** and enhanced protection against micro-cracks through the use of double tempered glass. By choosing this solution, investors receive a guarantee of stable energy production for decades, while ensuring the highest level of fire and mechanical safety, placing this series at the technological forefront of the industry. ## Notable figures - Efficiency of 23.8% is 0.8pp above the \*\*TOPCon 700-750W\*\* median (23.0%) - 238.2 W/m² power density - 8.0 W/m² more than \*\*TOPCon 700-750W\*\* median (230.2 W/m²), more power per roof area - At -0.29%/°C, hot weather performance is typical for \*\*TOPCon 700-750W\*\* panels - Bifaciality factor of 80% can add 4-12% extra yield with reflective mounting surface - In the top 3% for efficiency among all TOPCon panels ## Questions ### What warranty does the GCL NT12/66GDF series carry and what does it cover? The GCL NT12/66GDF series comes with a 12-year product warranty covering material and workmanship defects, as well as a 30-year linear power output warranty. After 30 years of operation, the module retains at least 87.4% of its rated nameplate power. The warranty is backed by the manufacturer GCL Solar, a globally established Tier 1 company, which significantly reduces the risk of complications in warranty claim enforcement. ### How does the N-type TOPCon technology in the GCL NT12/66GDF differ from conventional PERC cells? The N-type TOPCon cells used in the GCL NT12/66GDF exhibit significantly lower LID (Light Induced Degradation) compared to standard P-type PERC cells. Thanks to passivation layers on the rear cell surface, they achieve higher efficiency — reaching approximately 22.9% in this series — along with an improved temperature coefficient of -0.29%/°C. This translates into measurably higher kilowatt-hour yields over the entire system lifetime. ### What advantage does the bifacial design of the GCL NT12/66GDF offer and how much additional energy can be expected? The bifacial double-glass construction means the GCL NT12/66GDF generates power from both direct irradiance on the front side and reflected irradiance from the ground surface on the rear side of the module. Depending on the albedo of the ground surface and the mounting height, the manufacturer specifies a rear-side energy gain of up to 30%. The best results are achieved over light-colored gravel, white roofing membrane, or snow. ### What type of installation are the 730 W GCL NT12/66GDF modules suited for — can they be installed on a residential rooftop? The NT12/66GDF series, with modules rated up to 730 W and dimensions of approximately 2384×1303×35 mm and a weight of approximately 38.7 kg, is designed primarily for utility-scale ground-mounted farms and large commercial installations. The large form factor and module weight make handling on pitched roofs difficult and require a reinforced mounting structure. For prosumer installations on single-family homes, smaller modules from the same technology family are a more suitable choice. ### How many GCL NT12/66GDF 730 W panels are needed to build a 1 MW photovoltaic farm? At a peak power of 730 W per module, approximately 1,370 GCL NT12/66GDF panels are required to reach 1 MWp. The large 210 mm cell format delivers higher power from fewer modules compared to older-generation panels, which directly reduces the costs of mounting structures, cabling, and installation labor on the farm. ### Do GCL NT12/66GDF panels perform well in winter and at low temperatures in Poland? Yes, the low temperature coefficient of Pmax at -0.29%/°C means that GCL NT12/66GDF modules lose less power on hot days than older PERC modules (-0.35%/°C), while in freezing winter conditions they operate at elevated efficiency. The dual tempered glass construction increases resistance to snow loads and mechanical hail damage, which is particularly important in the Polish climate. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/1785317316684517-e977b1476639.pdf) ## Alternatives | Panel | Power | How it differs | | --- | --- | --- | | [AIKO AIKO-A700-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a700-mae78dw) | 700 W | -40 W, lighter, +1.2 pp | | [AIKO AIKO-A695-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a695-mae78dw) | 695 W | -45 W, lighter, +1.1 pp | | [AIKO AIKO-A690-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a690-mae78dw) | 690 W | -50 W, lighter, +0.9 pp | | [AIKO AIKO-A790-GRH78Dw](https://comparepv.com/panel/aiko-aiko-a790-grh78dw) | 790 W | +50 W, cooler, +0.8 pp | | [Trina Solar TSM-NEG21C.20Q-760](https://comparepv.com/panel/trina-solar-tsm-neg21c-20q-760) | 760 W | +20 W, cooler, +0.7 pp | | [AIKO AIKO-A785-GRH78Dw](https://comparepv.com/panel/aiko-aiko-a785-grh78dw) | 785 W | +45 W, cooler, +0.6 pp | | [Gokin GK-4-78HGBD-780M](https://comparepv.com/panel/gokin-gk-4-78hgbd-780m) | 780 W | +40 W, cooler, +0.5 pp | | [AIKO AIKO-A780-GRH78Dw](https://comparepv.com/panel/aiko-aiko-a780-grh78dw) | 780 W | +40 W, cooler, +0.5 pp | | [Jetion JT755SLk(B)](https://comparepv.com/panel/jetion-jt755slk-b) | 755 W | Cooler, lighter, +0.5 pp | | [Trina Solar TSM-NEG21C.20Q-755](https://comparepv.com/panel/trina-solar-tsm-neg21c-20q-755) | 755 W | +15 W, cooler, +0.5 pp | | [GCL GCL-M12/66GDF-655W](https://comparepv.com/panel/gcl-gcl-m12-66gdf-655w) | 655 W | -85 W, hotter, -2.7 pp | | [GCL GCL-M12/66H-660W](https://comparepv.com/panel/gcl-gcl-m12-66h-660w) | 660 W | -80 W, hotter, -2.6 pp | | [GCL GCL-M12/66H-665W](https://comparepv.com/panel/gcl-gcl-m12-66h-665w) | 665 W | -75 W, hotter, -2.4 pp | | [AIKO AIKO-A805-GRH78Dw](https://comparepv.com/panel/aiko-aiko-a805-grh78dw) | 805 W | +65 W, cooler, +1.3 pp | | [AIKO AIKO-A800-GRH78Dw](https://comparepv.com/panel/aiko-aiko-a800-grh78dw) | 800 W | +60 W, cooler, +1.1 pp | | [AIKO AIKO-A795-GRH78Dw](https://comparepv.com/panel/aiko-aiko-a795-grh78dw) | 795 W | +55 W, cooler, +1.0 pp | --- Source: https://comparepv.com/panel/gcl-gcl-nt12-66gdf-740 Not in this file, on the page: the I-V and temperature curves lifted from the manufacturer's datasheet, a thirty-year output simulator, a bifacial gain calculator and alternatives filtered by how closely they match these dimensions.