This paper proposes to modify the classic control of voltage source converters for photovoltaic generation and battery energy storage systems, using model predictive control for the outer-loop and the conventional vector oriented control for the inner loop, in order to improve the voltage profiles in weak distribution networks. The proposed approach combines the advantages of the conventional vector oriented control and the model predictive control. Simulations in Matlab/Simulink over a realistic weak distribution system, based on a Colombian primary feeder with deficit of reactive power, demonstrate the advantages of the proposed control.