PV Surge Protection Device Solar Panel DC Surge Protective Device SPD

Photovoltaic installations are key sources of renewable energy across the world and are increasing both in terms of size and number. The installations have a number of challenges which arise from their exposed nature and vast collection areas. The unique nature of the PV installations makes them vulnerable to overvoltage surges from lightning strikes and static discharges. The core challenge is protecting these installations against direct and indirect lightning strikes which present a high risk of causing damage.

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Solar Panel PV Combiner Box DC Surge Protective Device

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Photovoltaic PV Surge Protection Solutions

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The effects of direct or indirect lightning strike making it into the electrical system can be catastrophic. If significant damage is caused to the installation then the operator is faced with high repair costs to the equipment and a loss of revenue as a result of the loss of output. As a result of this, it is essential that the surges are intercepted before they take down the entire system by damaging the PV arrays, charge controller/inverter and combiner boxes.

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LSP is able to mitigate against these threats by providing a comprehensive protective solution to the customer. A range of certified PV DC surge protective devices is available to safeguard the electrical system of the PV installation, preventing damage. In addition to the surge protection devices, LSP has a large product portfolio covering the complete PV protective solution including T1 (Class I, Class B), T1+T2 (Class I+II, Class B+C), T2 (Class II, Class C) DC surge protective device.

PV system overview

To ensure full system protection against the propagation of overvoltage surges throughout the PV installation it is important to select the correct Surge Protection Device (SPD) for each part of the system in the DC, AC and data-line networks. The network diagram and table help to identify the key areas of SPD protection.

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Frequently asked questions (FAQs)

How does an SPD work?

A surge protector works by momentarily “switching” from an open circuit mode into a low impedance mode and shunting the surge energy to the ground, limiting the overvoltage to a safe level in the process. When the surge event is over the protector returns to its open circuit mode, ready for the next event.

Why does a PV installation require an SPD?

Due to the PV installation’s exposed nature and large collection area, it is increasingly prone to direct and indirect lightning strikes or transient overvoltage conditions. An SPD will prevent damage to the installation, preventing high repair costs to components and lost revenue from loss of output.

Which SPD is suitable to use?

This depends on a variety of factors including the geographical location, the equipment which is being protected and the importance of its operation. The configuration of the Earth and neutral conductors is also critical. Please send us email to sales[at]lsp-international.com to discuss your requirements.

What is a MOV?

A Metal Oxide Varistor (MOV) is a variable resistor typically made up of a large block of zinc oxide grains. They act like semi-conductors, an insulator below the conduction voltage and a low value resistor above it.

In conduction mode, the MOV diverts and dissipates the overvoltage transient to Earth. MOVs generally connect from the line conductors to Earth. The thickness of the MOV determines the clamping voltage and diameter determines the current capacity.

How long does an SPD last?

How long an MOV SPD lasts depends on the frequency and size of the overvoltage event. The greater the transient event, the greater the degradation of the MOV.

What is a modular SPD?

A modular SPD contains modules which can be replaced without replacing the entire SPD unit, making maintenance easy and minimizing time with reduced protection. The modules allow decreased labor and cost which is required for servicing the protector.

How to replace an SPD at the end of life.

Eaton is able to offer replacement plug-in modules for each of the parts on offer. The modules clip in and clip out without requiring the whole device to be unwired from the system.