Hourly Models to Estimate the Energy Produced by Photovoltaic Modules of Different Technologies

Two models to estimate the hourly energy produced by photovoltaic modules of different technologies under real operating conditions are presented. Traditional energy prediction models have shown limits for modules of amorphous technologies when the global radiation is mainly diffuse, because this type of modules is more sensitive to diffuse radiation. Additionally, traditional models do not take into account the spectral distribution of the incident radiation. That fact is a source of inaccuracy especially in photovoltaic technologies with a narrow spectral response such as amorphous silicon. Two models are proposed in this paper. One of them assumes that the energy produced by a module only depends on the incident irradiation and its working temperature. The other one is based on adding a variable that takes into account the spectral composition of solar radiation in the calculation of the energy produced. These models were estimated using hourly values. The hourly temperature of a module is obtained from the ambient temperature, solar irradiation and wind speed. The results obtained for modules of four different technologies, including thin film technologies, show the validity of proposed models.