Nowadays, many resources are being used to the generation of renewable energy. Among these resources, solar energy has been receiving more attention in the last years. The market of photovoltaic systems has been increased exponentially, but the government subsidies have been reduced dramatically in recent years. The return of the investment mainly relies on selling the energy produced during the photovoltaic plant lifetime. Thus, the photovoltaic system must be designed and controlled properly in order to ensure its lifetime and reliability.

The photovoltaic array consists of a combination of several photosensitive cells that capture the sun irradiance and, through the transfer of electrons, generates direct current at its terminals. However, the generated power has a nonlinear behavior with increasing voltage, requiring adjustment of parameters from experimental data, which are generally given by the manufacturers of the modules. To verify the simulation results with those found experimentally, a mathematical model must be developed considering all the characteristics of a photovoltaic cell, and then the equations are extended to the whole array used in the system.

The choice of an appropriate mathematical model for the photovoltaic cell is very important for testing the implementation of the maximum power point tracking control. Several papers describe different ways of modeling a photovoltaic module that can be classified by the level of complexity. The simplest models are based on equivalent circuits and represent the macroscopic generator with voltage and current at its terminals. More complex models take into account the physical representations of the semiconductor in order to provide depth information of the power generating cell.

We invite overview and original papers describing current and expected challenges along with potential solutions for photovoltaic systems: modeling and characterization. Both experimental and theoretical papers are welcome.

Potential topics include, but are not limited to:

• Maximum power point tracking techniques
• Model parametric identification of PV generators
• Photovoltaic ageing characterization
• Techniques for preventing system degradation