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GCL GCL-M12/66H-665W
GCL Brand review

GCL-M12/66H-665W

665 Wp PERC
ComparePV verdict

Middle of its segment, weak in heat

Rank 3,816 of 14,005
Compare panels Datasheet PDF
Power (Wp)
665
Typical for its class
Efficiency (%)
21.40
Typical · median 21.25%
Density (Wp/m²)
214.1
Typical · median 212.5
Temp (%/°C)
-0.350
Weak · bottom 10%
Weight (kg)
34.2
Typical · median 34.5 kg
Warranty (yrs)
25
Weak · bottom 21%

GCL GCL-M12/66H series feature large-size, half-cell technology, designed with the aim of maximizing energy yield in installations where the cost of energy throughout the entire life cycle is crucial. The application of P-type PERC monocrystalline cell technology and dense packing translates to better surface utilization and more predictable energy production under typical operating conditions. A key advantage of this series is its approach to operational risks - non-destructive cutting reduces susceptibility to micro-cracking, while refined material selection and processes support resistance to PID, helping maintain performance over time. The glass-backsheet construction facilitates integration with common mounting systems, and the module format helps reduce the costs of auxiliary equipment for farms (less construction, cabling, and installation work per unit of power). This is an excellent choice for projects where operational profitability and reliability are prioritized-particularly for ground-mounted installations, large industrial rooftops, and investments focused on stable returns.

Ranking

320 panels in the segment PERC 650-700 W
Metric This panel Median Position in segment Overall rank
Module efficiency 21.40% 21.25% Typical 8,323
Power density 214.1 212.5 Typical 8,250
Temperature coefficient -0.350 -0.340 Weak · bottom 10% 10,419
Weight per kWp 51.4 52.3 Typical 4,818
Performance warranty 25 yrs 30 yrs Weak · bottom 21% 9,798
Colour key Strong - top 25% Typical - middle 50% Weak - bottom 25%

Signals from the data

5 positive · 5 caution
Best for

Utility-scale, commercial and shaded-installations.

Not ideal for

Hot climates and owners who want a long output guarantee.

Watch-outs
-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.

What owners get
Long-standing BNEF Tier 1 status – bankability assurance

GCL-SI has maintained continuous BNEF Tier 1 listing for several consecutive years (confirmed by PV Magazine and RenewEconomy), enabling non-recourse project financing for utility-scale PV farms and reducing risk exposure for lending institutions.

210 mm large-format wafer + 132 half-cut cells

The 132 half-cut cell configuration on a 210 mm wafer delivers higher per-module output (660–680 Wp) and lower BoS costs: fewer racking components, less cabling, and reduced installation labor per kWp in commercial and ground-mount applications.

Non-destructive cutting – reduced microfracture risk

The non-destructive cutting technique minimizes mechanical stress on cells during manufacturing, lowering the risk of performance degradation caused by microcracks (EL defects) over the system's service life — particularly relevant for long-distance shipping and installations subject to high wind or snow loads.

PID resistance backed by third-party certification

The module has passed IEC 61701 (salt mist corrosion), IEC 62716 (ammonia resistance), and DIN EN 60068-2-68 (sand and dust) testing, qualifying it for deployment in demanding environments such as coastal zones and industrial sites.

Efficiency on par with PERC peers

The 21.2–21.9% efficiency range positions this series at the same level as direct PERC-class competitors (SpolarPV SPV680: 21.92%; Solaria SPVxxx: 21.92%), while also offering the added credibility of a Tier 1 manufacturer with a longer market track record.

Trade-offs
P-type PERC – a technology losing market ground

At the same power class (680 Wp), the competing AIKO Comet 3N72 achieves 25.2% efficiency using N-type ABC technology — an absolute advantage of 3.3 percentage points over the GCL-M12/66H series' maximum of 21.9%. PERC also exhibits higher LID degradation rates during the initial months of operation compared to N-type, which may translate into lower cumulative energy yield over the long term.

Monofacial only – no bifacial gain

The series does not offer a bifacial variant (is_bifacial: false), whereas many competing modules in this power class (e.g., GCL-M12/66GDF) can capture an additional 5–25% yield from rear-side albedo reflection. In ground-mount installations over light-colored soil or grass, this represents a tangible loss in energy production potential.

12-year product warranty – below premium-tier standard

The product warranty stands at 12 years, while premium manufacturers (LONGi Hi-MO X6, JA Solar DeepBlue 4.0 Pro) routinely offer 15 years as standard. For commercial projects financed over 15+ years, this gap may become a procurement disadvantage or necessitate additional equipment insurance coverage.

Notes from the database
  • Efficiency of 21.4% matches the PERC 650-700W median
  • Power density of 214.1 W/m² matches the PERC 650-700W median
  • Temperature coefficient of -0.35%/°C matches the PERC 650-700W median
  • Ranked #8323 out of 14005 panels for efficiency in the database

Specifications

Open datasheet PDF
Nominal power (Pmax) 665 Wp Nameplate at 1000 W/m², 25 °C
Module efficiency 21.40 % Typical Segment median 21.25%
Vmpp · Impp 38.00 V · 17.50 A Operating point at max power
Voc · Isc 45.80 V · 18.60 A Sizes the string length
Max system voltage 1500 V Longer strings than 1000 V modules
Dimensions 2384×1303×35 mm · 3.11 m² of roof
Weight 34.2 kg Typical Typical · median 34.5 kg
Cells 132 · PERC Monocrystalline
Coefficient Pmax -0.350 %/°C Weak bottom 10% of its segment
Coefficient Voc · Isc -0.280 · 0.050 %/°C
NOCT 45 °C At 800 W/m², 20 °C ambient
Product warranty 12 years Hardware defects only
Performance warranty 25 years Weak bottom 21% · median 30 yrs
Degradation 0.55 % Per year after the first

Simulations

Live - change any input
Lifetime output & value
30 years at 1200 kWh/kWp/year and €0.50 per kWh
Power in year 30
-
Lifetime energy
-
Energy value
-

Degradation from this panel's own datasheet figures. No inverter, soiling or shading losses.

Heat losses
-0.350 %/°C against a segment median of -0.340
-
Filter these
Size
Panel Power Eff. Temp. Weight Difference
GCL GCL-M12/66H-665W 665 W 21.40% -0.350 34.2 kg You are here
AIKO-A650-MAE72Mw 650 W 25.20% -0.260 27.0 kg Cooler, lighter, +3.8 pp
AIKO-A680-MDE72Mw 680 W 25.20% -0.260 29.0 kg Cooler, lighter, +3.8 pp
AIKO-A675-MDE72Mw 675 W 25.00% -0.260 29.0 kg Cooler, lighter, +3.6 pp
AIKO-A645-MAE72Mw 645 W 25.00% -0.260 27.0 kg Cooler, lighter, +3.6 pp
AIKO-A700-MAE78Dw 700 W 25.00% -0.260 34.5 kg Cooler, +3.6 pp, +5 yr warranty
AIKO-A695-MAE78Dw 695 W 24.90% -0.260 34.5 kg Cooler, +3.5 pp, +5 yr warranty
AIKO-G670-MCH72Mw 670 W 24.80% -0.260 28.2 kg Cooler, lighter, +3.4 pp
GCL-M12/66GDF-655W 655 W 21.10% -0.350 38.5 kg Heavier, -0.3 pp, +5 yr warranty
GCL-M12/66H-660W 660 W 21.20% -0.350 34.2 kg Very close match
AIKO-A805-GRH78Dw 805 W 25.10% -0.260 39.8 kg +140 W, cooler, +3.7 pp
AIKO-A800-GRH78Dw 800 W 24.90% -0.260 39.8 kg +135 W, cooler, +3.5 pp
AIKO-A795-GRH78Dw 795 W 24.80% -0.260 39.8 kg +130 W, cooler, +3.4 pp
AIKO-A790-GRH78Dw 790 W 24.60% -0.260 39.8 kg +125 W, cooler, +3.2 pp
TSM-NEG21C.20Q-760 760 W 24.50% -0.260 38.3 kg +95 W, cooler, +3.1 pp
AIKO-A785-GRH78Dw 785 W 24.40% -0.260 39.8 kg +120 W, cooler, +3.0 pp
GK-4-78HGBD-780M 780 W 24.30% -0.260 38.7 kg +115 W, cooler, +2.9 pp

Found 1390 panels of the same or similar size to this one, within ±10 mm. See them here Found 1400 panels of the same or similar size to this one, within ±25 mm. See them here Found 1400 panels of the same or similar size to this one, within ±50 mm. See them here Found 1432 panels of the same or similar size to this one, within ±100 mm. See them here

Common questions

6 answered
What warranty does the GCL-M12/66H series carry and what does it specifically cover?
The GCL-M12/66H series is backed by a 12-year product warranty covering material and workmanship defects, along with a 25-year linear power output warranty. The manufacturer guarantees that after 25 years of operation the module will retain at least 84.8% of its nominal rated power. For installations targeting long-term return on investment, this is one of the key parameters worth comparing across product series.
What do PERC and half-cut technologies mean in the GCL-M12/66H series and why do they matter?
PERC (Passivated Emitter and Rear Cell) incorporates a reflective passivation layer on the rear side of the cell, allowing photons that would otherwise pass through unconverted to be captured for a second conversion pass — the result is higher efficiency without a sharp increase in manufacturing cost. Half-cut technology, which splits each cell into two halves, reduces resistive losses and limits the impact of partial shading on the module's overall power output. GCL additionally applies non-destructive cutting, which minimizes the risk of microcracks during transportation and long-term operation.
How much does a GCL-M12/66H panel weigh and is it suitable for large industrial rooftops?
The module weighs approximately 34 kg and has dimensions of 2384 × 1303 × 35 mm. When planning installations on industrial or warehouse rooftops, this load must be factored into the structural design. The large module format delivers a clear BoS cost advantage — fewer mounting rails, connectors, and cables are required per unit of power, which typically lowers the overall installed cost for large-scale rooftop systems.
Are GCL-M12/66H panels resistant to PID and what does that mean in practice?
Yes, the GCL-M12/66H series is engineered with high resistance to Potential-Induced Degradation (PID). PID manifests as a progressive loss of module power output in systems where panels operate at high voltage relative to ground — a particularly critical issue in large utility-scale plants and long string configurations. Optimized encapsulant materials and tightly controlled manufacturing processes mitigate this effect, resulting in more stable energy yield over the full operational lifetime.
Is the GCL-M12/66H panel bifacial and can it be mounted on a white-surface racking system to generate additional energy?
No, the GCL-M12/66H series is a monofacial module in a glass-backsheet construction. It does not generate power from light reflected off the ground or underlying surface. If bifacial gain from albedo reflectance is a priority, you should consider other GCL series available in the GDF (glass-glass bifacial) variant. For typical ground-mount and rooftop installations without a dedicated high-reflectivity surface, the absence of bifacial capability is not a significant drawback.
How do GCL-M12/66H panels perform at high temperatures during summer?
The temperature coefficient of maximum power (Pmax) for this series is approximately −0.35%/°C. This means that for every degree Celsius above the STC reference temperature of 25°C, the module loses approximately 0.35% of its rated power. At a cell operating temperature of, for example, 65°C on a hot summer day, the power loss is approximately 14%. This is a typical result for P-type PERC cells — lower than older cell technologies, though N-type cells (TOPCon, HJT) achieve better coefficients in this regard. This figure should be taken into account when running annual energy yield simulations.
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