Notions of equivalent number of hours
When we buy a PV module, the supplier gives us its power – peak PC under standard conditions, that is to say for an insolation of 1 kW / m2 (1000 w / m2).
However in real conditions, the sunshine is much lower and variable during the day: sunshine is maximum at noon and zero at sunrise and sunset.
Let Esol be the daily irradiation at a given site.
The number of equivalent hours is given by:
Ne = Esol /1000 ( Esolen wh/m2)
Example: the daily solar irradiation of a site is equal to 2500kwh / m2.
Calculate the number of equivalent hours.
Ne = 2.5 / 1000 = (25000wh / m2) / 1000w / m2) = 2.5 hours.