Due to the nonlinear characteristics of a photovoltaic (PV) array, its regulation is highly dependent on the operating point. Focusing on a dc-dc boost converter, this paper first shows how the PV voltage and inductor current controls are affected by the PV array. It then proposes to emulate an impedance virtually connected to the PV array, making it possible to greatly improve the control robustness. Thanks to the proposed strategy, the crossover frequency variation for the whole operating range is reduced from 42 times for the traditional control to 3.5 times when emulating parallel resistance or to 1.4 times when emulating series and parallel resistances, all with simple implementation. Experimental results with a commercial PV inverter and a 4-kWp PV array validate the theoretical analysis and demonstrate the superior performance of the proposed control. This work was supported in part by Ingeteam Power Technology and in part by Spanish State Research Agency (AEI) FEDER-UE under Grant DPI2016-80641-R.