The study has been carried out in several photovoltaic plants connected to the grid in Spain. These plants are characterized by the fact that generation takes place in direct current, which is transformed into alternating current and after into high voltage to be delivered to the grid. This is the reason why the short-circuit study must be carried out on both sides of the plant. On the AC side, three-phase (L-L-L), two-phase (L-L & L-L-G) and single-phase (L-G) fault currents will be analyzed. While on the DC side, the maximum short-circuit current to be generated in the system will be studied, which will help to size the protective devices for maximum safety and generation.