Aiming at the problem of the increasing voltage over limit risk by a large number of distributed PV access network, this paper analyses the PV output characteristics under different weather types, presents a generalized weather type clustering method based on photovoltaic output fluctuation characteristics, and builds a method of PV output time series based on clearance theory. The model can reflect time series characteristics and volatility of actual PV output, the risk assessment index of system voltage exceeding the limits based on the probability and severity of node voltage at each time interval is established. On this basis, using hybrid approximation to solve the ultimate capacity of distributed PV access network is proposed. Finally, a typical IEEE 33-node power distribution system and an actual line of a region of China Southern Power Grid are taken as examples to analyze the risk of system voltage under different load characteristics, load levels and line types. From these three aspects, the limit capacity of distributed PV access network is evaluated. This work is supported by National Natural Science Foundation of China (No. 51377060).