For the potential problem of out of limit of voltage due to high penetration of photovoltaic（PV）generation in low voltage distribution networks

a simplified analytical approach for calculating the maximum capacity of the PV generation is studied in this paper. It firstly constructs the simplified model of distribution grid containing PV generation

derives the analytical formula for determining the permitted capacity of photovoltaic installations with unit power factor under the voltage constraint of low voltage system

based on the simplified network model. Furthermore

the analytical formula for determining the required additional reactive power compensation is given when the voltage exceeds the limit due to excessive output of photovoltaic generation. Finally

the characteristics of the photovoltaic inverter reactive power output are analyzed

and a simplified technique for determining the permitted capacity of photovoltaic power generation under the leading power factor is proposed.A case analysis is developed in one IEEE 33 node system with the help of DIgSILENT software

The effectiveness of the method is verified by way of comparing the calculation result with the method in the paper and time domain simulation result and the deviation between them complies with actual engineering requirement.Moreover

the reason of the error existed in the paper is also analyzed.