This study develops a new control strategy for an expandable grid-connected photovoltaic (PV) system. The proposed system performs dual functions of a PV generation and an active power filter, or either one. To this end, the grid current, instead of output current of the converter, is shaped to be a sinusoidal current in phase (or opposite phase) with the grid voltage. Furthermore, its reference current is generated in multiplying the voltage loop controller output by the grid voltage waveform, and therefore non-active components analysis for harmonics elimination and reactive power compensation in the conventional design is not necessary. As a result, the algorithm is simple and easy to implement, and only one sensor for current detection plus two voltage sensors are required. Experimental results verified the effectiveness of the proposed method. (C) 2013 Elsevier Ltd. All rights reserved.