Surge Protection of Photovoltaic System

Solar panels are a great way to offset electrical consumption charges, self-generate electricity and provide a high degree of electrical independence. Photovoltaic systems use solar energy to produce electricity and are becoming increasingly popular due to their efficiency, reliability and flexibility. Photovoltaic modules are generally set up on a roof or an open field where sufficient sunlight is available. As a result, these systems are exposed to all weather conditions and can be subject to damage from direct and indirect lightning effects. The need for comprehensive surge protection for a photovoltaic system should be assessed according to the Lightning Protection standard AS 1768 and the Installation and Safety standard for PV arrays AS/NZS 5033. For residential buildings located in a lightning area where the flash density Ng is greater than two flashes per square kilometre per year, AS/NZS 5033 recommends protection against overvoltage surges due to lightning.

A photovoltaic system can be made up of several components including modules, inverters, batteries and monitoring systems. Together, they allow the generation of electricity from sunlight. Electrical damage to these components, can lead to a whole process failure. The components consist of sensitive electronic devices which can easily get damaged from transient over-voltages. Repairs to the PV system, replacement of faulty inverters, or fault finding by maintenance personnel can be very costly. The loss of revenue resulting from downtime can bring a considerable loss to the project investment and the return on investment is delayed.

DEHN & Novaris are globally recognised brands for lightning and surge protection, offering different types of SPD’s for various applications and many years of experience in the field of photovoltaics. A correctly coordinated surge protection system will provide high system availability and sustainable investment protection.

Photovoltaic DC Protection

IPD offers a comprehensive range of Photovoltaic surge protectors from the DEHN and Novaris portfolios.

DEHN provides two ranges for PV applications, the DEHNcombo YPV and the DEHNguard M. DEHNcombo YPV SPD’s are prewired type 1 + type 2 combined lightning current and surge arresters. DEHNguard M YPV SPD’s are modular multipole surge arresters, for PV systems with or without remote signalling contact for monitoring devices (voltage free changeover contact). A patented three-step DC switching device and a proven fault-resistant Y circuit, together with fault indication by a red indicator flag in the inspection window make these devices so unique.

The Novaris SDPV surge diverters are shunt connected, specifically designed to provide photovoltaic system DC-side protection against damage from surges caused by lightning or over voltages. All mode protection and equal let through voltage from each line to earth and line to line, are key features of these products. The pluggable design allows for easy removal and replacement.

Over current fusing of an SPD on the DC side of a PV array is sometimes ineffective due to the limited short circuit current characteristics of PV panels. Care should be taken in the selection of an SPD for the DC side as it’s important to choose a DC Photovoltaic surge protector with a short circuit withstand current, greater than the short circuit current of the solar array string.

Building without external lightning protection

A Type 2 DC Surge protector should be installed on the DC side and a Type 2 AC Surge protector should be installed on the AC side of the inverter to protect the components of the PV system. A Type 2 AC surge protector should be installed on the incoming supply side.

Building with external lightning protection and sufficient separation distance

This scenario is similar to the previous application however, PV modules must be placed in the protection zone of the isolated air-termination system and the separation distance must be maintained (refer AS 1768). A Type 2 DC Surge protector should be installed on the DC side and a Type 2 AC surge protector should be installed on the AC side of the inverter to protect the PV system. A Type 1+2 combined surge protector should be installed on the incoming supply side

Building with external lightning protection and insufficient separation distance

If the separation distance between the external lightning .protection system and the PV modules cannot be maintained, lightning equipotential bonding must be installed. A Type 1 or Type 1+2 DC surge protector should be installed on the DC side and a Type 1+2 AC surge protector should be installed on the AC side of the inverter to protect the PV system. Type 1+2 combined SPD should be installed on the incoming supply side.