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Solar SPD installation
Solar SPD installation
Resource: https://youtu.be/f4iYfrLfzsA

Just as solar SPDs must be properly rated, they must also be properly installed. The correct solar SPD installation will ensure that the device is providing the level of protection it is rated for —and that it will continue to do so for the lifetime of the product. The instructions and tips in this guide will help you understand what is required to properly install a solar surge protection device.

Solar Surge Protection Device

The surge protection device, SPD, is the first line of defense against damaging voltage surges. Solar SPDs are engineered to provide a high level of protection against the damaging effects of lightning and utility-related electrical surges.

An SPD in solar system circuits is installed on the DC side of the system which is between the solar array and the inverter, and again on the AC side of the system, which is after the inverter. Additional SPDs may also be installed close to sensitive loads.

The surge protection device location will vary depending on the type of product being protected and the level of protection required. Generally, the various equipment and circuits must be connected to one. Here below are the general guidelines for SPD installation:

Surge protection device wiring diagram
Surge protection device wiring diagram
Resource: https://www.youtube.com/watch?v=vG0ifUmgvNI

Solar SPD Installation Guide

To ensure that your SPD is properly installed and that it will provide the level of protection it is designed to provide, it’s crucial that you follow the manufacturer’s instructions. That said, here is the solar SPD installation guide to provide you with an overview of what’s required.

The process to install surge protection devices in solar systems involves two basic steps:

  • Selecting the proper SPD location and installing the SPD in the selected location
  • Connecting the SPD to the electrical system

1. SPD Location

The first step in installing a solar SPD is to select the proper location for the device. There are three main classes of solar SPD based on the specified location or installation point: the main SPD, the circuit SPC, and load SPD.

Main Surge Protector

The main surge protector is designed to be installed at the service entrance, between the utility power source or solar array and the inverter. Main SPDs provide surge protection for the entire electrical system, including all branch circuits.

In the solar system, this type of SPD is mounted close to the panels. The SPD for solar panel protects against direct lightning strikes, and must be properly rated for the higher voltages that the strikes can cause.

Circuit Surge Protector

The circuit surge protector is a type 2 SPD and usually provides secondary protection. This protection device is designed to be installed at the main service panel, between the main SPD and the branch circuit breakers.

Circuit SPDs provide surge protection for specific circuits, such as those that power computers and other sensitive electronic equipment.

Load Surge Protector

The load surge protector is a type 3 SPD and provides tertiary protection. It is normally installed at the point of use, between the branch circuit breaker and the electronic equipment. Load SPDs provide surge protection for electronic equipment and appliances.

2. SPD Connection

Solar SPD installation guidelines also recommend the proper connection of the SPD to the electrical system. The SPD should be connected to the phase (hot) conductor, neutral conductor, and the ground conductor.

The solar SPD connection must always ensure connection to ground, since surge protection devices typically work by providing a low impedance path to ground for the surge current.

Once the SPD is properly installed and connected, the last step is to test the device to ensure that it is functioning correctly. SPD manufacturers provide instructions on how to properly test their products alongside their installation instructions.

Solar SPD installation diagram
Solar SPD installation diagram
Resource: https://powerforum.co.za

Solar SPD Installation Tips

To ensure a successful solar SPD installation, various rules must be followed. These will help avoid any problems and will guarantee the correct functioning of the device in dissipating surges. The rules include those that concern the SPD regulations of your country, manufacturer guidelines, and proper electrical safety practices.

1. Make sure that the selected SPD is properly rated for the application. The SPD voltage rating must be greater than the maximum expected voltage of the system. The current rating, too, should not be less than the maximum surge current that the system can experience.

2. The SPD must be installed as close to the point of entry of the electrical system as possible. This will minimize the length of the conductor between the SPD and electronic equipment and prevent unwanted oscillation voltages.

3. The SPD location must provide adequate space for the proper installation and future maintenance of the device. The location must also be accessible for testing purposes.

4. Do not install the SPD in an area where it can be easily damaged by physical impact or exposure to harsh chemicals or corrosive fumes.

5. The selected location must have a suitable ground conductor system. The ground conductor must be properly sized and connected to the grounding bus bar or electrode system.

6. All conductors must be properly sized and installed in accordance with the manufacturer’s instructions and surge protection device regulations.

7. The distance between the different surge protecting devices should be as short as possible. Although not always easy to implement, installers must ensure no more than 10 feet (3 meters) of the conductor is between the SPDs.

8. The solar array should be properly grounded according to the manufacturer’s instructions. This is essential for the proper functioning of the SPD.

9. Once the SPD installation is completed, all system wiring must be inspected to ensure that it meets the requirements of your region’s Electrical Code.

Surge Protector Lifespan

Your solar SPD will have a finite lifespan. The number of surges that it can dissipate before needing to be replaced will depend on the type of surge protector, its voltage and current ratings, and the magnitude and waveform of the surges.

In general, however, most SPDs have a lifespan of a few years. After this time, the device will need to be replaced in order to continue providing adequate protection against voltage surges.

Most solar SPDs today come with a mechanism to disconnect from the system when they have reached the end of their lifespan. This is often in the form of a visual indicator, such as a colored strip: green for a functioning protector and red for a protector that needs to be replaced.

Once the surge protector lifespan has come to an end, it is important to replace it with a new one as soon as possible. Failing to do so can result in damage to electronic equipment if a surge occurs.


Solar surge protection devices make an essential part of any solar energy system. They provide protection from surges that can damage sensitive electronic equipment. Solar SPDs are available in a variety of types. It is, therefore, important to select the right SPD for the application and to follow the manufacturer’s installation instructions carefully. With proper installation, solar SPDs will provide system protection that other devices cannot on their own.

Related Resource
IGOYE Surge Protection Device Catalog
inverter catalog