Standard Test Conditions (STC)
Standard Test Conditions (STC) : Conditions under which a module is typically tested in a laboratory: (1) Irradiance intensity of 1000 W/square meter (0.645 watts per square inch), AM1.5 solar reference spectrum, and (3) a cell (module) temperature of 25 degrees C, plus or minus 2 degrees C (77 degrees F, plus or minus 3.6 degrees F). [IEC 1215]