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Suntech STP660S-D66/Wmh
Suntech Brand review

STP660S-D66/Wmh

660 Wp TOPCon
ComparePV verdict

Middle of its segment, short guarantee

Rank 4,193 of 14,005
Compare panels Datasheet PDF
Power (Wp)
660
Typical for its class
Efficiency (%)
21.20
Weak · bottom 4%
Density (Wp/m²)
212.5
Weak · bottom 5%
Temp (%/°C)
-0.340
Weak · bottom 6%
Weight (kg)
33.5
Typical · median 34.6 kg
Warranty (yrs)
25
Weak · bottom 2%

Ultra X Plus is a solar panel series built around 210mm monocrystalline silicon cells, designed for large-scale commercial and industrial installations where every square meter of roof or ground space counts. The use of PERC technology combined with half-cut and SMBB cell design helps reduce current losses and improve heat dissipation, allowing the modules to perform reliably even under high temperatures and partial shading. The series is available in both monofacial and bifacial configurations, giving investors the flexibility to choose the solution best suited to a specific site and their goal of maximizing energy yield from the rear side of the panel. The large cell format translates into high power density per module, which meaningfully lowers the per-watt cost of the installation (BoS) and shortens installation time for the same panel count. This makes it a solution aimed primarily at installers of solar farms and utility-scale projects seeking high efficiency and lower LCOE without compromising on mechanical durability, confirmed by resistance to heavy snow and wind loads. Ultra X Plus thus combines production scale, proven cell technology, and configuration flexibility in one market-mature series.

Ranking

249 panels in the segment TOPCon 650-700 W
Metric This panel Median Position in segment Overall rank
Module efficiency 21.20% 22.40% Weak · bottom 4% 9,076
Power density 212.5 223.7 Weak · bottom 5% 8,959
Temperature coefficient -0.340 -0.290 Weak · bottom 6% 8,778
Weight per kWp 50.8 53.2 Typical 4,172
Performance warranty 25 yrs 30 yrs Weak · bottom 2% 9,798
Colour key Strong - top 25% Typical - middle 50% Weak - bottom 25%

Signals from the data

0 positive · 3 caution
Best for

Utility-scale and shaded-installations.

Not ideal for

Owners who want a long output guarantee, tight roof space and roofs where every square metre has to count.

Watch-outs
25 year performance warranty

Bottom 2% of the TOPCon 650-700 W segment, against a median of 30 yrs. Ranked 9,798th in the whole database.

21.20% module efficiency

Bottom 4% of the TOPCon 650-700 W segment, against a median of 22.40%. Ranked 9,076th in the whole database.

212.5 watts per square metre

Bottom 5% of the TOPCon 650-700 W segment, against a median of 223.7. Ranked 8,959th in the whole database.

Notes from the database
  • At 21.2% efficiency, this panel is 1.2pp below the TOPCon 650-700W median of 22.4%
  • Power density of 212.5 W/m² is 11.2 W/m² below TOPCon 650-700W median (223.7 W/m²) - needs more roof space
  • At -0.34%/°C, loses 0.05pp more power per degree than TOPCon 650-700W median (-0.29%/°C)
  • At 33.5 kg, this panel is 1.1 kg lighter than TOPCon 650-700W median (34.6 kg) - easier handling during installation
  • In the top 65% for efficiency among all TOPCon panels

Specifications

Open datasheet PDF
Nominal power (Pmax) 660 Wp Nameplate at 1000 W/m², 25 °C
Module efficiency 21.20 % Weak Segment median 22.40%
Vmpp · Impp 38.05 V · 17.35 A Operating point at max power
Voc · Isc 46.05 V · 18.35 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 33.5 kg Typical Typical · median 34.6 kg
Cells 132 · TOPCon Monocrystalline
Coefficient Pmax -0.340 %/°C Weak bottom 6% of its segment
Coefficient Voc · Isc -0.260 · 0.050 %/°C
NOCT 42 °C At 800 W/m², 20 °C ambient
Product warranty 12 years Hardware defects only
Performance warranty 25 years Weak bottom 2% · median 30 yrs
End-of-warranty output 84.8 % Equals 542 W guaranteed
Degradation 2.00 → 0.55 % 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
-

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

Heat losses
-0.340 %/°C against a segment median of -0.290
-
Filter these
Size
Panel Power Eff. Temp. Weight Difference
Suntech STP660S-D66/Wmh 660 W 21.20% -0.340 33.5 kg You are here
AIKO-A650-MAE72Mw 650 W 25.20% -0.260 27.0 kg Cooler, lighter, +4.0 pp
AIKO-A680-MDE72Mw 680 W 25.20% -0.260 29.0 kg Cooler, +4.0 pp, +5 yr warranty
AIKO-A675-MDE72Mw 675 W 25.00% -0.260 29.0 kg Cooler, +3.8 pp, +5 yr warranty
AIKO-A645-MAE72Mw 645 W 25.00% -0.260 27.0 kg Cooler, lighter, +3.8 pp
AIKO-A700-MAE78Dw 700 W 25.00% -0.260 34.5 kg Cooler, +3.8 pp, +5 yr warranty
AIKO-A695-MAE78Dw 695 W 24.90% -0.260 34.5 kg Cooler, +3.7 pp, +5 yr warranty
AIKO-G670-MCH72Mw 670 W 24.80% -0.260 28.2 kg Cooler, lighter, +3.6 pp
STP650S-D66/Pmh+ 650 W 20.90% -0.340 37.5 kg Heavier, -0.3 pp, +5 yr warranty
STP655S-D66/Wmh 655 W 21.10% -0.340 33.5 kg Very close match
STP665S-D66/Wmh 665 W 21.40% -0.340 33.5 kg Very close match
STP670S-D66/Wmh 670 W 21.60% -0.340 33.5 kg +10 W, +0.4 pp
STP675S-D66/Wmh 675 W 21.70% -0.340 33.5 kg +15 W, +0.5 pp
AIKO-A805-GRH78Dw 805 W 25.10% -0.260 39.8 kg +145 W, cooler, +3.9 pp
AIKO-A800-GRH78Dw 800 W 24.90% -0.260 39.8 kg +140 W, cooler, +3.7 pp
AIKO-A795-GRH78Dw 795 W 24.80% -0.260 39.8 kg +135 W, cooler, +3.6 pp
AIKO-A790-GRH78Dw 790 W 24.60% -0.260 39.8 kg +130 W, cooler, +3.4 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 is the maximum power output of the Suntech Ultra X Plus panel?
Panels in the Ultra X Plus series reach a maximum power output of up to 675 Wp. This is achieved through large 210 mm silicon cells combined with half-cut and SMBB technology, which increase power density within the module. As a result, fewer panels are needed to reach the same installed capacity, shortening installation time and reducing mounting structure costs.
What is TOPCon technology used in the Ultra X Plus, and how does it differ from PERC?
TOPCon (Tunnel Oxide Passivated Contact) is a newer-generation cell technology than PERC, used in the Ultra X Plus series. An additional passivation layer on the rear side of the cell reduces carrier recombination, resulting in higher module efficiency and a smaller power loss at high temperatures compared to standard PERC panels. In practice, this means higher energy yield, especially during summer and under high irradiance.
What warranty comes with Suntech Ultra X Plus panels?
The manufacturer provides a 15-year product warranty covering material and workmanship defects, along with a 30-year linear power output warranty. This means the panel must maintain a guaranteed percentage of its initial power throughout its service life, and as a Tier 1 manufacturer, Suntech offers reliable after-sales support for the entire warranty period.
Is the Suntech Ultra X Plus a bifacial panel?
No, this specific variant of the Ultra X Plus series is a monofacial module, generating energy only from the front side. The manufacturer also offers this series in a bifacial version, but choosing between the two depends on the mounting type and site conditions - the monofacial version is best suited for rooftops and installations without reflective ground surfaces.
Is Suntech a reliable manufacturer, and what does Tier 1 status mean?
Suntech is a Chinese manufacturer with Tier 1 status according to BloombergNEF's classification, indicating financial stability, in-house production lines, and a proven track record of supplying modules to large-scale energy projects worldwide. For investors, Tier 1 status matters for bank financing, as lenders and insurers often require Tier 1 panels as a condition for approving project loans.
Are Ultra X Plus panels suitable for large-scale solar farms?
Yes, the Ultra X Plus series was designed for commercial, industrial, and utility-scale installations. The large cell format and power output of up to 675 Wp reduce the number of panels, support structures, and cabling needed for a given installed capacity, directly lowering Balance of System (BoS) costs and the levelized cost of electricity (LCOE).
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