A NOCT is Nominal Operating Cell Temperature, the temperature at which Cells in a Module operate under Standard Operating Conditions (SOC), which are: irradiance of 0.8 kW/m2, 20_C ambient temperature, and average windspeed of 1 m/s, with the wind oriented parallel to the plane of the array, and all sides of the array fully exposed to the wind.
List of books: NOCT