DC isolator switch (DC switch-disconnectors) are electrical devices used in DC (direct current) systems to switch and disconnect the flow of current. These switch-disconnectors are designed to handle high DC voltages and currents. They provide a means of isolating the electrical circuit for maintenance or safety purposes. In PV applications, DC isolator switches are used to manually disconnect the solar panels for maintenance, installation or repair purposes.
In most solar PV installations, two DC isolator switches are connected to a single string. Normally, one switch is placed close to the PV array and the other close to the DC end of the inverter. This is to ensure that disconnection can be achieved at ground and roof level. DC isolators can come in polarized or non-polarized configurations. For DC isolator switches that are polarized, they come in two, three and four pole configurations.