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

The CalLab PV modules test- and calibration laboratory offers its customers precise measurement services of the highest quality. Essentially, our performance measurements differ under standard test conditions (STC) in the smallest measurable measurement uncertainty, as described below:

Calibration services: CalLab PV Modules offers highly accurate calibration of PV modules under standard test conditions (STC) in accordance with the international standard IEC 60904-1 Ed. 3 (2020-09). The measurement uncertainty of only ± 1.1% as well as our quality assurance places us among the leading international calibration laboratories. The CalLab PV Modules is accredited as a calibration laboratory according to DIN EN ISO/IEC 17025:2018 (accreditation certificate D-K-11140-02-00, ILAC-MRA).

Precision measurements are carried out in accordance with IEC 60904-3. The smallest measurable measurement uncertainty is ± 1.5 % for the module performance. As with the calibrations mentioned above, a correction of the spectral deviations is mandatory for precision measurements. The measurement of the spectral response of the PV module is carried out either on cell level or on module level (cell level – destructive test; module level - non destructive test).

For the measurement of spectral response (SR) on cell level, an additional reference module is therefore required for each module type, which must correspond exactly with the structure and materials of the module to be measured. When measuring the SR on module level, no additional module is required, this is carried out directly on the test object.

Standard measurements are carried out in accordance with IEC 60904-1. The measurement uncertainty for module output is ± 1.8 %.

Precision and standard measurements are carried out in our test laboratory CalLab PV Modules according to DIN EN ISO/IEC 17025:2018 (accreditation certificate D-PL-11140-33-00).

Thin film measurement: In the case of thin film modules, the measurement uncertainty is dependent on the technology used. We will gladly provide you with the details of precise values on request.