The current deregulation trend in the electric power generation has led the utilities to adapt solar energy generation into their existing infrastructure. The main challenge of solar energy integration into power grid is its time-varying (intermittency) nature due to cloud shading of PV panels which depends on weather conditions. This paper discusses the impacts of large-scale solar energy penetration into power distribution network. Moreover, the necessity of time-series simulation and field measurement data to investigate the impacts of intermittency of large-scale solar energy penetration is explained. It has been shown that the sampling rate of measurement data has an important role while inadequate sampling rate of measurement data may lead to miss the high-variability points which have significant effects on the operation of system. In this paper, the real field measurement data of a sample circuit form Southern California (SCE) are considered.