Siemens ST20 solar module: datasheet and specifications
20 Wrated power
15.6 VVmp
21 VVoc
4.1 kgweight
n/rdimensions not recorded
Siemens ST20: product photograph restored from the original low-resolution picture.
The ST20 is the 20 W CIS thin-film module, which the source says was designed for 12 V systems. Siemens announced series production of the ST20 and ST40 on 10 March 1999 as the next higher-power CIS step; the 20 W rating comes with a 15.6 V Vmp and 1.29 A. It is the only ST page whose table shows the humidity, freeze and damp-heat condition (85 % RH). The weight is 8.8 lb (4.1 kg); dimensions are not recorded.
Electrical data
continuous thin film; CIS thin film.
Parameter
ST20 (12 V)
Rated power Pmax (W)
20
Minimum power Pmin (W)
18
Current at Pmax, Imp (A)
1.29
Voltage at Pmax, Vmp (V)
15.6
Short-circuit current, Isc (A)
1.48
Open-circuit voltage, Voc (V)
21
Derived figures
Quantity
Value
How it was obtained
Power per weight
4.9 W/kg
calculated
Voc at −20 °C (ST20 (12 V))
25.5 V
calculated with the datasheet Voc coefficient
Vmp with 60 °C cells (ST20 (12 V))
13.0 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
The datasheet gives a Voc coefficient of −0.1 V/°C for the whole module. Scaled to the Vmp, a 15.6 V module falls to about 13.0 V with 60 °C cells, below the roughly 14.4 V needed to absorb a 12 V lead-acid battery. Siemens’ own pitch for CIS was battery-charge power in low light. In 5 peak-sun-hours the 12 V version adds roughly 4.8 Ah a day to a 12 V battery (Imp × 5 h × 0.75). The warranty has only the 5-year, 90 % tier.
Full datasheet tables
Thermal
Parameter
Unit
Value
Nominal operating cell temperature (NOC)
°C
47 ± 2
Change of Isc with temperature
.26 mA/°C
Change of Voc with temperature
-0.1 V/°C
Qualification tests
Parameter
Unit
Value
Temperature cycling range
°C
−40 to +85
Humidity, freeze, damp heat condition
% RH
85
Maximum system voltage
V
25 (as published; the ST table layout is garbled, confirm on the original)
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
Weight
kg (lb)
4.1 (8.8)
Warranty (5)
Parameter
Unit
Value
Power ≥ 90 % of minimum power
years
5
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.
