Siemens SM20 solar module: datasheet and specifications
20 Wrated power
14.5 VVmp
18 VVoc
2.5 kgweight
567 × 328 mmoutline
Siemens SM20: product photograph restored from the original low-resolution picture.
The SM20 delivers 20 W from 30 cells on a 567 × 328 mm frame, 2.5 kg. Its Vmp is 14.5 V and Voc 18 V, the lowest Vmp of any 12 V module in the range, and its maximum system voltage is 20 V. It is not among the modules Siemens’ application pages recommend for telecom, gas and oil, water or traffic equipment.
Electrical data
30 cells in series; single-crystal silicon.
Parameter
SM20 (12 V)
Rated power Pmax (W)
20
Minimum power Pmin (W)
18
Current at Pmax, Imp (A)
1.38
Voltage at Pmax, Vmp (V)
14.5
Short-circuit current, Isc (A)
1.6
Open-circuit voltage, Voc (V)
18
Derived figures
Quantity
Value
How it was obtained
Outer area
0.186 m²
calculated from length × width
Power per area
108 W/m²
calculated; Pmax ÷ area at STC
Module efficiency
10.8 %
calculated on outer dimensions (cell efficiency is higher)
Power per weight
8.0 W/kg
calculated
Voc at −20 °C (SM20 (12 V))
20.6 V
calculated with the datasheet Voc coefficient
Vmp with 60 °C cells (SM20 (12 V))
12.1 to 12.9 V
approximate range; see the note below the table
Rough daily energy
75 Wh
calculated: Pmax × 5 peak-sun-hours × 0.75 system efficiency; a planning figure, not a measurement
With 30 cells in series the Vmp is 14.5 V at 25 °C. With 60 °C cells it falls to about 12.1 to 12.9 V (the datasheet gives no Vmp coefficient: the lower figure assumes a typical −0.47 %/K, the upper scales the Voc coefficient), a margin of -2.3 to -1.5 V against 14.4 V. The margin is negative or marginal, so on hot days this module may not finish charging a lead-acid battery. In 5 peak-sun-hours the 12 V version adds roughly 5.2 Ah a day to a 12 V battery (Imp × 5 h × 0.75).
Full datasheet tables
Thermal
Parameter
Unit
Value
Nominal operating cell temperature (NOC)
°C
45
Change of Isc with temperature
+0.6 mA/°C (+0.04 %/K)
Change of Voc with temperature
-0.058 V/°C (−0.34 %/K)
Qualification tests
Parameter
Unit
Value
Temperature cycling range
°C
−40 to +85
Humidity, freeze, damp heat condition
% RH
85
Maximum system voltage
V
20
Wind loading or surface pressure
N/m² (PSF)
2400 (50)
Maximum distortion (4)
degrees
1.2
Hailstone impact withstand (diameter @ velocity)
mm @ m/s (in @ mph)
25 @ 23 (1.0 @ 52)
Physical
Parameter
Unit
Value
Number of series cells
count
30
Length
mm (in)
567 (22.3)
Width
mm (in)
328 (12.9)
Depth
mm (in)
35 (1.4)
Weight
kg (lb)
2.5 (5.6)
Warranty (5)
Parameter
Unit
Value
Power ≥ 90 % of minimum power
years
10
Notes from the datasheet. (1) Electrical values at standard test conditions: irradiance 1000 W/m², cell temperature 25 °C, spectrum per ASTM E892 (air mass 1.5). (2) Nominal operating conditions: 800 W/m², ambient 20 °C, wind 1 m/s. (3) Qualification tests per CEC 503. (4) Diagonal lifting of a module corner with three corners fixed. (5) Warranty applies to the original consumer purchaser; see the full limited warranty for conditions. The tier percentages refer to the minimum power rating (Pmin), not the rated power.
