Modelling of hourly solar irradiance from field measurements in Bandar Lampung

Utilization of photovoltaic systems has increased recently for both large-scale and home applications. Consequently, a better understanding of solar irradiance uncertainty in planning and operation of a photovoltaic system is a necessity. This work aims to develop an hourly probabilistic model of solar irradiance, as it is important for most capacity planning or system sizing and simulation. In this research, field measurements of solar irradiance were carried out for six months with a one-minute interval from 6 a.m. to 6 p.m. at the specific measurement site in Bandar Lampung. The probabilistic models were then developed for each hourly solar irradiance. Our contribution is to split samples into four-modes or four-groups for describing the multi-modality of the distribution. The developed model based on estimates of the shape parameters was used to reconstruct the hourly solar irradiance and tested against the original data by graphical inspection and the Kolmogorov-Smirnov 2-sample test satisfactorily. Results obtained from this work can be extended for optimal photovoltaic system sizing and simulations.