Fraunhofer Institute for Solar Energy Systems ISE

STC measurements

Measurements under standard test conditions for determining V-I and electrical output characteristics

Measurement conditions (STC)

1000W/m²
AM 1.5 global
25°C

With details provided of the following output characteristics

Short circuit current (Isc)
Open circuit voltage (Voc)
Maximum output (Pmpp)
Current at Pmpp (Impp)
Voltage at Pmpp (Vmpp)
Fill factor (FF)
Efficiency (eta)

Measurement uncertainty

A distinction is made between precision, standard and thin film measurements.

Standard measurements are carried out in accordance with IEC 60904-1. The measurement tolerance for module output is +/- 2.5 %.

Precision measurements are performed in accordance with IEC 60904-3. The measurement tolerance for module output is +/- 1.3 %. In order to carry out precision measurements, the spectral response of the module must first be measured. The measurement of spectral response requires an additional reference module with an identical structure and composition as that of the module to be measured.

In the case of thin film modules, the measurement uncertainty is dependent on the technology used. We would be pleased to provide details of precise values on request.