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Product Information Overview / Novaris | Lightning and Surge Protection for Photovoltaic Systems

Lightning strikes are an unpredictable natural phenomenon. However, the way equipment can be protected from lightning strikes is predictable.

In 2003 Novaris Technologies, Malaysia was established to expand manufacturing capability as product sales grew globally. The company is positioned to provide the highest quality electrical surge protection products in the world, dedicated to providing protection solutions to prevent equipment damage caused by direct lightning strikes, surges and other electrical disturbances on power and data signalling lines.

Equipment may be damaged by either direct lightning strikes to the structure, direct lightning strikes to the power line or from indirect strikes caused by cloud to ground or cloud to cloud strikes. These latter events cause induction and earth potential rises. It should be noted that transient electrical disturbances similar to lightning may be caused by power switching operations and power line faults.

Nonetheless, like all electrical equipment, photovoltaic systems can be damaged by both direct and indirect lightning strikes and other overvoltage disturbances caused by electrical switching operations, load switching and so on.

Photovoltaic systems are designed to have an operational life of 20 or more years so the chances of an electrical disturbance causing damage over this time can be quite high. Protection against these disturbances will help to ensure that a long operational life is achieved.

Protection Options

(a) Building without external Lightning Protection System (LPS)

This is by far the most common case where a building has no external LPS and so the risk of a direct lightning strike is not considered. Building with a roof-mounted solar array and inverter mounted near the main switchboard. Normally the inverter would be mounted close to the main switchboard and in a location that is readily accessible.

(b) Building with external LPS

A building with an external lightning protection system (LPS). The solar array frame must be bonded to the LPS. In this case, the solar array frame and its earthing conductor form part of the LPS. Thus, the partial lightning current will flow in the array bonding and earthing conductors. These must be sized accordingly and 35mm2 is recommended.

Surge Protective Device Selections

(a) SPD for AC PV

SPDs for AC protection may be either, NSP, SDD, surge diverters or SSP, series surge protectors.

(b) SPD for DC PV

The SPD for the DC input to the inverter and solar array must be designed specifically for DC application. AC SPDs are not suitable because upon failure their disconnect circuitry may not quench the arc. AC SPDs rely upon a voltage zero-crossing to quench the arc. This does not occur with DC. So the arc may persist, with the attendant hazard of fire.