Grid connected photovoltaic inverters always adopt a cascade control system in interfacing photovoltaic cells for maximum power point tracking purposes. Unbalanced grid voltage generate a double frequency component in the dc-link voltage. Either selecting larger capacitance value or decreasing the crossover frequency of the dc-link voltage control decreases distortion of grid current references. Large electrolytic capacitors used in the dc-link lead to reliability reduction due to short lifetime. Decreasing the crossover frequency improves the quality of grid current at the expense of poor response to input power transients. Based on a small signal linear model, this paper reveals that lower input impedance and smooth output admittance of the inverter adopts capacitor current control strategy both effectively improves response to input power transients and provides low grid current THD. Experiments are performed with 200 μF of dc-link capacitance for a 3-kW cascade PV inverter.