The invention concerns a method for evaluating photovoltaic energy production for an energy supply facility (11) installed on a site (1), the energy supply facility (11) comprising at least one electricity production unit (12) having at least one photovoltaic module (14); characterized in that the photovoltaic energy production evaluation method comprises the following steps: —determining past or predictive irradiance values for the site (1) on which the energy supply facility (11) is installed, the determination being carried out for time intervals of between one second and two years, and —evaluating the photovoltaic power generated as a function of the determined irradiance values and numerical values prerecorded in a database (30), this database (30) including, for each day of the year and different times of each day, prerecorded numerical values for determining the photovoltaic electrical power generated as a function of the irradiance.