Surge Protective Devices (SPDs) provide protection against electrical surges and spikes, including those caused directly and indirectly by lightning. They can be utilized as complete devices or as components within electrical equipment.

Photovoltaic (PV) system converts solar energy into direct current electricity. PV system ranges from small, rooftop-mounted or building-integrated systems with capacities from a few to several tens of kilowatts, to large utility-scale power stations of hundreds of megawatts. The potential impact of lightning events increases with PV system size. At locations with frequent lightning, unprotected PV systems will suffer repeated and significant damages. This results in substantial repair and replacement costs, system downtime and loss of revenue. Properly installed surge protective devices (SPDs) will minimize the potential impact of lightning events.

Sensitive electrical equipments of PV system like AC/DC Inverter, monitoring devices and PV array must be protected by surge protective devices (SPD).

To determine the proper SPD module for the PV system and its installation, you must know:

1.the lightning round flash density;

2.the system's operating temperature;

3.the system's voltage;

4.the system's short circuit current rating;

5.the level of waveform that is to be protected against (indirect or direct lightning); and the nominal discharge current.

The SPD that is provided on the dc output must have a dc MCOV equal to or greater than the maximum photovoltaic system voltage of the panel.