The standard test condition used for a photovoltaic solar panel or module is defined as: 1000 W/m 2, or 1 kW/m 2 of full solar irradiance when the panel and cells are at a standard ambient temperature of 25 o C with a sea level air mass (AM) of 1. We know that photovoltaic (PV) panels and modules are semiconductor devices that generate an. . These test conditions are commonly referred to as STC or Standard Test Conditions for solar panels. These standards include compliance with industry regulations such as UL. . Plane of Array Irradiance, the sum of direct, diffuse, and ground-reflected irradiance incident upon an inclined surface parallel to the plane of the modules in the photovoltaic array, also known as POA Irradiance and expressed in units of W/m2. Performance Ratio based on measured production. . The calibration of solar modules involves determining electrical parameters such as the maximum possible power, the short-circuit current and the open-circuit voltage.