The main design objective of photovoltaic (PV) systems has been, for a long time, to extract the maximum power from the PV array and inject it into the ac grid. Therefore, the maximum power point tracking (MPPT) of a uniformly irradiated PV array and the maximization of the conversion efficiency have been the main design issues. However, when the PV plant is connected to the grid, special attention has to be paid to the reliability of the system, the power quality, and the implementation of protection and grid synchronization functions. Modern power plants are required to maximize their energy production, requiring suitable control strategies to solve the problems related to the partial shading phenomena and different orientation of the PV modules toward the sun. Moreover, the new policy concerning the injection of reactive power into the grid makes the development of suitable topologies and control algorithms mandatory. A general view of actual solutions for applications of the PV energy systems is presented. This article covers several important issues, including the most reliable models used for simulation, which are useful in the design of control systems, and the MPPT function, particularly in distributed applications. The main topologies used in the PV power processing system and, finally, grid connection aspects are discussed, with emphasis on synchronization, protections, and integration.

This paper introduces a novel maximum power point tracking (MPPT) technique aimed at maximizing the power produced by photovoltaic (PV) systems. The largest part of the MPPT approaches presented in the literature are based on the sensing of the PV generator voltage. On the contrary, in this paper, a current-based technique is proposed: the sensing of the current in the capacitor placed in parallel with the PV source is one of the innovative aspects of the proposal. A dual control technique based on an inner current loop plus an outer voltage loop allows to take profit of the fast current tracking capability of the inner current loop while the voltage loop benefits from the logarithmic dependency of the PV voltage on the irradiation level. The features of the proposed algorithm, particularly in terms of tracking of irradiation variations and disturbance rejection, are supported by theoretical analysis, simulations, and experimental results. The technique described in this paper is patent pending.

In practical photovoltaic (PV) installations the operating conditions of the panels the PV array is made of are different owing to different factors. Such irregular conditions are known as ‘mismatching conditions’ and produce multiple maxima in the power‐voltage curves of any PV array. The traditional maximum power point tracking (MPPT) techniques are able to track one of those maxima, but they cannot guarantee the extraction of the maximum power the PV array would be able to deliver. To overcome this problem, many techniques have been presented in the literature: they use one converter for the entire array (centralised MPPT), one converter for each part of the array (distributed MPPT) or they reconfigure the PV array (RMPPT). This paper presents the general architectures used by 61 different MPPT techniques, by discussing their main advantages and disadvantages, in order to give to the reader a comprehensive view of both the control strategies and the architectures for extracting the maximum power from a mismatched PV field. Moreover, the widely adopted techniques for each hardware structure are presented in a structured and compact way, thus providing to the reader some guidelines regarding the technique's operation principle and hardware requirements.