Solar PV energy systems have become one of the most researched and developed renewable energy alternatives due to the long lifetime and reduced maintenance of its components. However, considering the low efficiency in the conversion from light to electrical energy, the optimization of the power electronics converters which deliver the energy from the panels to the electrical grid has fundamental importance in terms of overall efficiency. One of the key elements in a PV system, designed to increase the efficiency, is the maximum power point tracking (MPPT) algorithm which finds the operating point where the maximum power is extracted from the panels. Several MPPT algorithms have been proposed in literature, ranging from the simple but powerful perturb and observe to very sophisticated algorithms involving artificial neural networks. All these methods have been designed with a very slow dynamics hence they cannot follow accurately abrupt modifications of the power curve produced when the irradiation changes. In this paper, a simple MPPT algorithm based on the modification of the switching signals and the analysis of the resulting voltage and power deviation is proposed. This algorithm allows to follow accurately the changes of maximum power point produced by fast variations in the irradiation. Simulation results to validate the proposed algorithm and comparisons with previously published algorithm are shown.