Grid-connected photovoltaic (PV) systems are currently developed by merging a PV array and a DC/AC inverter which are designed separately, without considering the impact of the PV array operational characteristics on the power losses of the DC/AC inverter. In this paper, a co-design technique is presented, where the optimal design parameters of the PV array and DC/AC inverter in a grid-connected PV system are calculated concurrently through a unified design process. The proposed technique enables to optimally match the PV array configuration and the DC/AC inverter structure. A study has been performed, where the PV systems synthesized by applying the proposed co-design technique are compared with the PV system configurations comprising PV arrays and DC/AC inverters that have been designed separately, through distinct optimization processes based on various alternative optimization objectives. The design results for two installation sites, with different meteorological conditions during a year, demonstrated that only the proposed co-design optimization technique is capable of ensuring the maximization of the annual energy production of the overall grid-connected PV system.