A maximum power point tracking algorithm for single-stage converters connecting photovoltaic (PV) panels to a single-phase grid is presented in this paper. The algorithm is based on the application of the "ripple correlation control" using as perturbation signals the current and voltage low-frequency oscillations introduced in the PV panels by the single-phase utility grid. The proposed control technique allows the generation of sinusoidal grid currents with unity power factor. The algorithm has been developed to allow an array of PV modules to be connected to the grid by using a single-stage converter. This simple structure yields higher efficiency and reliability when compared with standard solutions based on double-stage converter configurations. The proposed maximum power point tracking algorithm has been numerically simulated and experimentally verified by means of a converter prototype connected to a single-phase grid. The results are presented in the paper, showing the effectiveness of the proposed system.