This paper presents the analysis of the impact of dispersed source production on the electric distribution network. The focus is on the production of electric energy by photovoltaic systems in public distribution networks. Photovoltaic systems may in certain cases influence voltage quality in public distribution networks, which is determined by the EN 50160 standard. Photovoltaic systems affect the voltage profile and harmonic distortion of current and voltage. Ensuring the appropriate voltage profile is especially important in radial networks because of eventual huge voltage drops. Many photovoltaic systems on a radial network with relatively high short-circuit impedance and relatively low short-circuit power can be problematic with regard to the permitted level of harmonic distortion, particularly at lower power. The analysis of power quality is based on real measurements of total harmonic distortion (THD) on four existing photovoltaic systems and two transformer stations in the urban electric distribution networks. (C) 2017 Elsevier Ltd. All rights reserved.