A method for evaluating the operation of a photovoltaic installation in an environment, the photovoltaic installation comprising several photovoltaic modules, the method being implemented by a computer and comprising the following steps: a. collecting input data relative to the environment and to the photovoltaic installation, b. determining irradiance parameters to be used by an irradiance calculating model on the basis of the input data, at least one irradiance parameter being a spatial variation of the albedo, called spatially resolved albedo, of a surface reflecting the sunlight on the photovoltaic modules, c. determining the effective irradiance received by the photovoltaic installation on the basis of the irradiance calculating model, of the input data and of the determined irradiance parameter(s), and d. determining the effective energy produced by the photovoltaic installation as a function of the determined effective irradiance and of the input data.