In the last years, photovoltaic systems are receiving a growing research attention due to their fundamental role in energy efficiency worldwide. The last research activities on photovoltaic systems are mainly focused on modeling, sizing and control of stand-alone and grid-connected photovoltaic systems, on centralized Maximum Power Point Tracking (MPPT) and distributed MPPT, on photovoltaic arrays reconfiguration, on storage sizing and control optimization, on detection of mismatching operating conditions, fault diagnosis and maintenance programming, on prediction and modeling of solar radiation, and output power plants forecast. On the basis of these considerations, the goal of this topic collection is to focus on the latest theoretical studies, numerical algorithms, scientific results and applications of photovoltaic systems. This topic collection has the objective of bringing together scientists adopting several approaches and working on the above topics and of promoting and sharing as much as possible top-level research in the field of photovoltaic systems. 

Keywords:
•    Maximum power point tracking techniques;
•    Power electronics in photovoltaic systems;
•    Sizing and optimization of photovoltaic components and systems;
•    Photovoltaic modelling;
•    Forecasting techniques;
•    Reconfiguration algorithms;
•    Faults diagnosis;
•    Mismatching detection;
•    Decision processes for grid operators.