A method for evaluating the operation characteristic of grid-connected PV systems in multiple interconnection was proposed and a suppression of PV electric energy which is reduced by an automatic voltage control unit was estimated using a yearly scale simulation. The automatic voltage control unit is one of the PV inverter functions. In Japan, PV systems must be provided with this function to maintain within 101 V +/- 6 V for the standard voltage of 100V according to the technical recommendations. The automatic control voltage unit adjusts the distribution-line voltage at a connected point using leading reactive power or active power. Especially, the adjustment of active power will cause a suppression of PV electric energy. (C) 2002 Elsevier Science B.V. All rights reserved.