Translations:PV module/15/en

Irradiance is a measurement of sunlight intensity (power) that constantly varies throughout the day naturally as the sun moves through the sky, but also due to weather. Irradiance measured over time is referred to as insolation and is vitally important for measuring PV system production over time. On a clear day irradiance typically will reach its peak around noon. 1000 W/m² is an irradiance value for a clear day around noon, which means that it is not likely to be normal operating condition in most locations. Irradiance can only be measured with specialized and sensitive equipment, but it can be estimated as irradiance has a direct relationship with the current and power that the module outputs. PV module are given their power ratings by testing them at 1000 W/m² of irradiance. Irradiance below 1000 W/m² reduces cell current and irradiance above 1000 W/m² increases cell current. Irradiance can increase beyond 1000 W/m² under certain geographic and meteorological conditions. The formula for calculating production based upon irradiance is: