A good understanding of the stochastic characteristics of photovoltaic(PV)power is essential to analysis of the influence of PV power integration. However

solar radiation intensity is influenced by the solar-earth revolution and the long-term weather processes. As a result

PV power series as a whole exhibits a mixture of stochastic process with annually and diurnally periodical components rather than a purely stochastic series. So how to distinguish between the random and periodical patterns of the PV power and extract the random component from the time series is particularly important. A method is proposed to extract the random component from the PV power series based on the global solar radiation model and the least square method. Multiple dominant factors influencing the PV output are considered. Moreover

the statistical characteristics of the random component are analyzed at length using the real-world measurement of the PV power from Gansu and Germany.