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S-Energy Brand review

SL85-66BDL-645R

645 Wp PERC Bifacial 70%
ComparePV verdict

Middle of its segment, modest efficiency

Rank 4,248 of 14,005
Compare panels Datasheet PDF
Power (Wp)
645
Strong · top 7%
Efficiency (%)
20.79
Weak · bottom 15%
Density (Wp/m²)
207.9
Weak · bottom 18%
Temp (%/°C)
-0.340
Typical · median -0.340
Weight (kg)
37.9
Weak · 3.9 kg above median
Warranty (yrs)
30
Typical · median 30 yrs

The S-Energy SL85-66BDL series are modules designed for installations where high energy production from a given area and resistance to harsh operating conditions are crucial. The use of a bifacial design allows not only direct sunlight to be utilized, but also reflected light from the ground, which significantly improves energy yields in ground-mounted and roof-mounted installations with light-colored surfaces. The dual glass variant (glass-glass) enhances operational stability over time, reduces the risk of degradation, and better protects the cells from moisture and micro-cracks, which is important in the Polish climate.

The SL85-66BDL is based on monocrystalline PERC technology, which provides a good balance between efficiency and predictable performance under varying sunlight conditions. This makes it a suitable choice for investors who want to build installations with a long lifespan, minimizing the risk of performance losses. The series also features a long power warranty, which facilitates investment planning in commercial and industrial projects.

Ranking

217 panels in the segment PERC 600-650 W
Metric This panel Median Position in segment Overall rank
Module efficiency 20.79% 21.38% Weak · bottom 15% 10,558
Power density 207.9 213.8 Weak · bottom 18% 10,494
Temperature coefficient -0.340 -0.340 Typical 8,778
Weight per kWp 58.8 55.7 Weak · bottom 17% 11,888
Performance warranty 30 yrs 30 yrs Typical 21
Colour key Strong - top 25% Typical - middle 50% Weak - bottom 25%

Signals from the data

0 positive · 3 caution
Best for

Commercial and utility-scale.

Not ideal for

Tight roof space, weight-limited structures and roofs where every square metre has to count.

Watch-outs
20.79% module efficiency

Bottom 15% of the PERC 600-650 W segment, against a median of 21.38%.

58.8 kg per kWp

Bottom 17% of the PERC 600-650 W segment, against a median of 55.7.

207.9 watts per square metre

Bottom 18% of the PERC 600-650 W segment, against a median of 213.8.

Notes from the database
  • Efficiency of 20.8% is 0.6pp below the PERC 600-650W median (21.4%)
  • At 207.9 W/m², this panel generates 5.9 W/m² less per unit area than PERC 600-650W median (213.8 W/m²)
  • Temperature coefficient of -0.34%/°C matches the PERC 600-650W median
  • At 37.9 kg (3.9 kg above PERC 600-650W median of 34.0 kg), requires checking roof load capacity
  • Bifaciality factor of 70% can add 4-10% extra yield with reflective mounting surface

Specifications

Open datasheet PDF
Nominal power (Pmax) 645 Wp Nameplate at 1000 W/m², 25 °C
Module efficiency 20.79 % Weak Segment median 21.38%
Vmpp · Impp 37.26 V · 17.31 A Operating point at max power
Voc · Isc 45.74 V · 18.22 A Sizes the string length
Max system voltage 1500 V Longer strings than 1000 V modules
Dimensions 2383×1302×35 mm · 3.10 m² of roof
Weight 37.9 kg Weak Weak · 3.9 kg above median
Cells 66 · PERC Monocrystalline
Bifaciality 70 % Rear output as a share of front
Coefficient Pmax -0.340 %/°C Typical median -0.340 of its segment
Coefficient Voc · Isc -0.250 · 0.040 %/°C
NOCT 45 °C At 800 W/m², 20 °C ambient
Product warranty 12 years Hardware defects only
Performance warranty 30 years Typical median 30 yrs · median 30 yrs
End-of-warranty output 85.0 % Equals 548 W guaranteed
Degradation 2.00 → 0.45 % First year, then annual

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
-
With bifacial gain
-

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

Heat losses
-0.340 %/°C against a segment median of -0.340
-
Bifacial gain
Rear gain over light concrete: -
-

Model: bifaciality × albedo × 0.6 view factor. A first-order estimate, not a yield simulation.

Alternatives

All S-Energy panels
Filter these
Size
Panel Power Eff. Temp. Weight Difference
S-Energy SL85-66BDL-645R 645 W 20.79% -0.340 37.9 kg You are here
AIKO-A650-MAE72Mw 650 W 25.20% -0.260 27.0 kg Cooler, lighter, +4.4 pp
AIKO-A680-MDE72Mw 680 W 25.20% -0.260 29.0 kg Cooler, lighter, +4.4 pp
AIKO-A675-MDE72Mw 675 W 25.00% -0.260 29.0 kg Cooler, lighter, +4.2 pp
AIKO-A645-MAE72Mw 645 W 25.00% -0.260 27.0 kg Cooler, lighter, +4.2 pp
AIKO-A695-MAE78Dw 695 W 24.90% -0.260 34.5 kg +50 W, cooler, +4.1 pp
AIKO-G670-MCH72Mw 670 W 24.80% -0.260 28.2 kg Cooler, lighter, +4.0 pp
LR7-72HVHF-670M 670 W 24.80% -0.260 28.5 kg Cooler, lighter, +4.0 pp
SL85-66BDL-650R 650 W 20.95% -0.340 37.9 kg Very close match
SL85-66BDL-655R 655 W 21.11% -0.340 37.9 kg +10 W, +0.3 pp
SL85-66BDL-660R 660 W 21.27% -0.340 37.9 kg +15 W, +0.5 pp
SL85-66BDL-665R 665 W 21.43% -0.340 37.9 kg +20 W, +0.6 pp
AIKO-A805-GRH78Dw 805 W 25.10% -0.260 39.8 kg +160 W, cooler, +4.3 pp
AIKO-A800-GRH78Dw 800 W 24.90% -0.260 39.8 kg +155 W, cooler, +4.1 pp
AIKO-A795-GRH78Dw 795 W 24.80% -0.260 39.8 kg +150 W, cooler, +4.0 pp
AIKO-A790-GRH78Dw 790 W 24.60% -0.260 39.8 kg +145 W, cooler, +3.8 pp
TSM-NEG21C.20Q-760 760 W 24.50% -0.260 38.3 kg +115 W, cooler, +3.7 pp

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Common questions

6 answered
What is the maximum power output and efficiency of the S-Energy SL85-66BDL panel?
The S-Energy SL85-66BDL reaches a peak power of 665 Wp with module efficiency up to 21.43%. The series spans from 645 to 665 Wp, allowing precise sizing for each project. This efficiency level — high for PERC technology — means more energy can be harvested from the same roof or ground area compared to standard monocrystalline modules of an older generation.
What does the bifacial design mean in the SL85-66BDL series, and when does it actually pay off?
A bifacial module generates power from both the front and rear surfaces. In the SL85-66BDL, the rear side captures light reflected from the ground (albedo), boosting annual energy yield — especially in ground-mounted systems with light-colored substrates, white gravel, or snow cover. Depending on ground albedo, the bifacial gain can add several percentage points to annual production compared to a monofacial equivalent.
What warranty does the S-Energy SL85-66BDL come with?
S-Energy provides a 12-year product warranty covering manufacturing defects and a 30-year linear power warranty. After 30 years, the module is guaranteed to retain at least 84.95% of its rated output. The extended power warranty simplifies yield forecasting and supports financing models for commercial and industrial PV projects.
Do the S-Energy SL85-66BDL panels perform well in winter and in variable weather conditions?
Yes. The dual-glass (glass-glass) construction protects cells more effectively against moisture ingress, frost, and microcracks than standard backsheet designs — an important advantage in Central European climates. The PERC cell technology maintains predictable performance under diffuse irradiance, common during autumn and winter. The temperature coefficient of Pmax is -0.34%/°C, indicating moderate power loss at elevated summer temperatures.
What types of installations are the S-Energy SL85-66BDL modules best suited for?
The SL85-66BDL series is primarily designed for utility-scale ground-mounted PV farms and large commercial or industrial flat-roof systems. The module's large footprint (2383 × 1302 mm) and weight of 37.9 kg require robust mounting structures, making it less suitable for small residential pitched roofs. The bifacial gain is best realized where the rear side of the module has unobstructed access to reflected light.
Is S-Energy a Tier 1 manufacturer, and is it worth investing in?
S-Energy is a South Korean solar panel manufacturer with a long track record in the industry; however, it is not currently listed as a Tier 1 manufacturer by financial advisory agencies. For projects requiring project financing, it is advisable to confirm the brand's acceptability with the lending institution in advance. From a technical standpoint, the SL85-66BDL offers strong performance specs and generous warranty terms, which are key factors when evaluating long-term reliability.
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