Home/Insights/Importance of protective switchgear in solar PV installations

Correct protective switchgear is extremely important for safe operation of any PV system.

Solar PV arrays generate direct current (DC) output, which is then fed into PV inverter.

Our latest range of hybrid PV inverters incorporate DC switch which allows a safe disconnect between PV array and the rest of the system. Under no circumstances should one attempt to manually disconnect a solar panel from PV array without first switching off DC breaker in the inverter! In such situation, an electric arc would result, potentially causing a fire, equipment damage, and potentially lethal electric shock hazard!

The inverter itself incorporates a multitude of inbuilt protection features, including automatic residual current monitoring unit, overcurrent protection, over and under voltage and frequency protection, surge suppression and arc fault protection. However apart from protective devices inbuilt in inverter itself, additional protective switch-gear is also necessary. In the first instance, it is necessary to feed alternating current output of the inverter through a special isolator switch, which should be positioned next to the inverter. This switch, which must be rated for correct current, voltage and installation site environmental requirements (IP rating) isolates the inverter from the grid.

AC cable of a correct type would then feed output from this switch to the main consumer unit, typically located next to main meter downstairs. It is there, next to the main consumer unit, that additional residual current device (RCD, commonly known as “salvavita”) and miniature circuit breaker (MCB) must be installed before connection of PV system output to the house main switch. RCD protects people from a possible electric shock, which can occur should any part of live wire come into contact with any electrically conducting object. A correctly selected RCD would disconnect the circuit in milliseconds, preventing such sock hazard.

On the other hand, a correctly sized MCB would protect the cable and other hardware from possible short circuit fault in the system. When a short circuit occurs, such as for instance when cable insulation is mechanically damaged, MCB would immediately detect rising current and trip, preventing damage. Furthermore, it is important to ensure that all components of a PV system are properly grounded, and that the earth electrode on the property actually functions correctly!

Every PV installation by Virtue Solaris is safety-tested by independent warranted engineer, to ensure that all protective devices operate correctly.

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