Photovoltaic plants (PV) are among the fastest growing energy sources in the world, with annual growth rates of 25-35% over the last ten years. Furthermore, most of the new PV capacity has been installed in the distribution grid as distributed generation bringing new challenges for the grid operators. As the use of PV plants continues to expand, concern about its potential impact on the stability and operation of the electricity grid grow as well. This study assesses the effects of different levels of PV penetration on the distribution network voltage conditions and power system losses. A representative distribution system feeder was selected to perform PV power plant influence analysis with realistic data for PV production and distribution network load.