This paper deals with improving the effectiveness of the control system for the DC/AC grid connected photovoltaic (PV) inverter. The three-phase DC/AC grid connected PV inverter control system consists of two main control loops: (i) external loop to control the DC link voltage. (ii) An internal control loop for regulating the inverter current by controlling both direct and quadrature currents (Id, Iq) that are provided by the inverter phase-locked loop (PLL). The main component of each control loop is the proportional-integral (PI) controller, whose optimal gains are challenging tasks. The optimal PI controller gains should be selected to achieve multiobjectives such as increasing inverter efficiency, stability and power factor while decreasing the total harmonic distortion (THD) in the inverter output current as well as voltage. For this purpose, various meta-heuristic techniques (MHTs) are suggested with a comprehensive comparative study such as: (i) Whales Optimization Algorithm (WOA), (ii) Grey Wolf Optimization (GWO) algorithm, (iii) Antlions Optimization algorithm (ALO) and (iv) Moth Flame Optimization (MFO) algorithm. The numerical results attained through MatlabTM-Simulink reveal that the WOA technique is more superior than the three others studied MHTs in enhancing the inverter efficiency, stability and power factor with minimum THD.