STC : Standard Test Conditions
The Standard Test Conditions for the specification of PV modules are normalised operating conditions when testing the module. They are defined as:
- 1000 W/m² Irradiance (global when in outdoor conditions).
- 25°C Module temperature,
- AM 1.5 Spectrum, i.e. a normalised solar spectrum corresponding to the crossing of 1.5 times the "normal" atmosphere (vertical air mass at the sea level).
For CPV (concentrating modules), the reference irradiance is specified in terms of DNI value (direct component).
Until Spring 2011, it was usually 800 or 850 W/m2 - not always clear.
The present convention has fixed it at 1000 W/m².