A rapid method for sizing and placing of distributed electricity generation (DES) systems in an electric transmission network in respect to voltage has been developed and successfully validated. The new tool presented is in particularly useful for avoiding overvoltage situations, which are critical for the whole electricity system. The results show that DES placement closer to the transformer side is always more beneficial in terms of voltage than at the end of the line. Depending on the size of the DES unit, both up and downstream flow of power may occur. The method can be used for investigating a range of different placement and sizing configurations. (C) 2009 Elsevier Ltd. All rights reserved.