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Wmh vs Pmh+ 13 of 19 identical Swap Change panels

Suntech STP660S-D66/Wmh vs Suntech STP660S-D66/Pmh+

Suntech STP660S-D66/Wmh
STP660S-D66/Wmh
660 Wp 21.20 % TOPCon
Open panel page Datasheet PDF
VS
Suntech STP660S-D66/Pmh+
STP660S-D66/Pmh+
660 Wp 21.20 % TOPCon Bifacial
Open panel page Datasheet PDF
The verdict

Pmh+ leads on the differences that matter

The largest is performance warranty: 5 yrs longer. 13 of 19 comparable parameters are identical.

See all 6 differences
How alike are they
13 of 19 comparable
parameters are identical
identical differs
01

What actually differs

6 of 19 parameters
Parameter Wmh Pmh+ Difference
Performance warranty 25 yrs 30 yrs 5 yrs longer
Weight 33.5 kg 37.5 kg 4.0 kg lighter
Weight per kWp 50.8 kg/kWp 56.8 kg/kWp 6.1 kg/kWp lighter
Product warranty 12 yrs 15 yrs 3 yrs longer
Annual degradation 0.55 %/yr 0.45 %/yr 0.10 %/yr slower
Bifacial No Yes No vs Yes
02

What it means on a roof

Thirty years of production
Each panel's own declared degradation curve, at 1,200 kWh/kWp a year
Same temp coeff. for both panels (-0.340 %/°C), so a warmer roof scales both curves by the same factor: the totals fall together and neither panel gains on the other.
Wmh
21,390 kWh
Pmh+
21,734 kWh
Lifetime gap
344 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario Wmh Pmh+
Standard test conditions 25 °C 100.0% of rated power 660 W 660 W
Cool, bright day 40 °C 94.9% of rated power 626 W 626 W
Typical summer roof 55 °C 89.8% of rated power 593 W 593 W
Hot roof 70 °C 84.7% of rated power 559 W 559 W
03

Full specification

Parameter Wmh Pmh+ Difference
Power and efficiency
Rated power 660 Wp 660 Wp Same
Module efficiency 21.20 % 21.20 % Same
Power density 212.5 Wp/m² 212.5 Wp/m² Same
Open-circuit voltage 46.05 V 46.05 V Same
Voltage at max power 38.05 V 38.05 V Same
Short-circuit current 18.35 A 18.35 A Same
Current at max power 17.35 A 17.35 A Same
Temperature
Temperature coefficient -0.340 %/°C -0.340 %/°C Same
Mechanical
Dimensions 2384x1303x35 mm 2384x1303x35 mm Same
Module area 3.106 m² 3.106 m² Same
Weight 33.5 kg 37.5 kg -4.0 kg for Wmh
Weight per kWp 50.8 kg/kWp 56.8 kg/kWp -6.1 kg/kWp for Wmh
Warranty and degradation
Product warranty 12 yrs 15 yrs +3 yrs for Pmh+
Performance warranty 25 yrs 30 yrs +5 yrs for Pmh+
Annual degradation 0.55 %/yr 0.45 %/yr -0.10 %/yr for Pmh+
Technology
Cell technology TOPCon TOPCon Same
Cell type Monocrystalline Monocrystalline Same
Cell count 132 132 Same
Bifacial No Yes No vs Yes
04

Against the whole database

14,005 panels
Efficiency
#9,076 vs #9,076
Tied - the same position in the database
Power density
#8,959 vs #8,959
Tied - the same position in the database
Heat behaviour
#8,778 vs #8,778
Tied - the same position in the database
Weight
#4,172 vs #10,874
Wmh leads by 6,702 places
Warranty
#9,798 vs #21
Pmh+ leads by 9,777 places
Overall
#4,193 vs #2,610
Pmh+ leads by 1,583 places
05

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06

Written summary

07

Questions about this pairing

Which panel is better: Suntech STP660S-D66/Wmh or Suntech STP660S-D66/Pmh+?
According to our database: both panels are closely matched on key specs - the decision often comes down to price and local availability. See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Suntech STP660S-D66/Wmh and Suntech STP660S-D66/Pmh+?
Suntech STP660S-D66/Wmh has a module efficiency of 21.20%, while Suntech STP660S-D66/Pmh+ is 21.20%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Suntech STP660S-D66/Wmh use vs Suntech STP660S-D66/Pmh+?
Suntech STP660S-D66/Wmh uses TOPCon cells; Suntech STP660S-D66/Pmh+ uses TOPCon. Modern n-type technologies (TOPCon, HJT, BC) typically deliver higher efficiency and lower degradation compared to older PERC (p-type) cells.
What is the warranty on Suntech STP660S-D66/Wmh and Suntech STP660S-D66/Pmh+?
Suntech STP660S-D66/Wmh has a 25 years power warranty; Suntech STP660S-D66/Pmh+ has a 30 years power warranty. The power warranty guarantees a minimum percentage of rated output at the end of the warranty period (typically 80-87%). Product (materials) warranties are usually shorter.
Are Suntech STP660S-D66/Wmh and Suntech STP660S-D66/Pmh+ bifacial panels?
Suntech STP660S-D66/Pmh+ is bifacial (captures light from both faces); Suntech STP660S-D66/Wmh is monofacial. Bifacial panels work best on ground mounts or raised structures with a light-coloured surface underneath.

Shop prices: See 22 Suntech offers

Every figure here is from the manufacturers' own datasheets - a dash means the value is not published, never an estimate. The thirty-year projection and the temperature scenarios are calculations from those figures, and each states its assumption above.