Large amount of distributed PV generators connected into distribution feeder will cause the out-of-limit of voltage deviation. The calculation models of voltage drop caused by loads and voltage rise caused by PV generator are established under different loads or PV distribution along the line, and the maximum PV power injected into the feeder without causing over-voltages is proposed assuming the bus voltage deviation is reaching the upper limit. The maximum PV penetration level of 10 kV typical distribution line is derived under the condition that PV generation is of the same power distribution rule with load, and the voltage margin at the head end of feeder without causing over-voltage is provided. The analysis results show that over-head line can carry more PV power than cable, over-voltage will be avoided by controlling the PV power according to the connection point voltage, and suitably lowering the bus voltage will also allow more PV connecting to the feeder.