The direct current section of a typical photovoltaic system consists of a generator formed by parallel strings of solar panels connected in series. Along with the specific characteristic of solar modules and strings (e.g.inability to shut off the voltage other than by obscuring the solar panels, or generation of short-circuit currents with values near to those produced in normal conditions), the presence of voltage in the range of 600-1500V DC and beyond requires a very careful assessment of the protection and isolating devices to be used. Devices that must be able to withstand direct fault currents under high voltages.