Siemens ST40 solar module: datasheet and specifications
40 Wrated power
16.6 VVmp
22.2 VVoc
n/aweight
n/rdimensions not recorded
Siemens ST40: product photograph restored from the original low-resolution picture.
The ST40 is the largest CIS thin-film module in the range, rated 40 W (34.4 W minimum) at a Vmp of 16.6 V and Voc 22.2 V. In April 1999 Siemens announced that NREL had verified 12.1 % conversion efficiency for a large-area ST40, which it called a record for thin-film power modules. The release announcing ST20/ST40 series production gives the ST40 as 38 Wp, a small difference from the datasheet’s 40 W rating. The weight printed on the page (5.2 lb) is identical to the ST10’s and is probably a copy error, so it is not used here.
Electrical data
continuous thin film; CIS thin film.
Parameter
ST40 (12 V)
Rated power Pmax (W)
40
Minimum power Pmin (W)
34.4
Current at Pmax, Imp (A)
2.41
Voltage at Pmax, Vmp (V)
16.6
Short-circuit current, Isc (A)
2.59
Open-circuit voltage, Voc (V)
22.2
Derived figures
Quantity
Value
How it was obtained
Voc at −20 °C (ST40 (12 V))
26.7 V
calculated with the datasheet Voc coefficient
Vmp with 60 °C cells (ST40 (12 V))
14.0 V
approximate range; see the note below the table
Rough daily energy
150 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 16.6 V module falls to about 14.0 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 9.0 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
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
not used: the value (5.2 lb) equals the ST10’s and is probably a copy error
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.
