How to Choose Photovoltaic SPDs?

Photovoltaic power generation is a renewable clean energy source that is widely used in various countries and regions. Lightning and surges pose a significant threat to photovoltaic power generation systems. To protect the normal operation of photovoltaic systems, it is crucial to choose and install appropriate surge protection devices (SPDs).

Why install photovoltaic SPDs?

The equipment in a photovoltaic system that may need protection includes:

• Photovoltaic arrays;

• Inverters, including interfaces with low-voltage AC systems and DC systems;

• Cabling within the photovoltaic system;

• Components installed between the inverter and photovoltaic array;

• Equipment for controlling and monitoring the photovoltaic system.

These surges and overvoltages can degrade and damage the performance of the photovoltaic system, even causing failures that lead to equipment breakdown, burning, carbonization, and in severe cases, fires. Therefore, installing photovoltaic SPDs in photovoltaic systems is essential. They effectively absorb and release these transient overvoltages, reducing them to a range that equipment can tolerate, thereby protecting the normal operation of the equipment and enhancing the reliability and safety of the photovoltaic system.

Selection of photovoltaic SPDs

The selection and installation of SPDs for protecting photovoltaic systems depend on numerous factors, such as the characteristics of low-voltage power systems (e.g., overhead lines or underground cables) and the characteristics of the equipment being protected; whether there are external lightning protection devices installed to protect the photovoltaic system from direct lightning strikes.

Selection of DC-side photovoltaic SPDs

• Photovoltaic Inverter: A device that converts DC power (batteries) into AC power. On the DC side of the inverter, a plug-in modular photovoltaic-specific Level 2 DC SPD should be installed;

• DC Distribution Cabinet: Not within the direct lightning protection zone, a photovoltaic-specific Level 1 DC SPD should be installed;

• Combiner Box: To reduce connections between photovoltaic modules and the inverter, facilitate maintenance, and improve reliability, a DC combiner box is typically added between the photovoltaic modules and the inverter, with several photovoltaic strings connected in parallel to the combiner box. A plug-in modular photovoltaic-specific Level 2 DC SPD should be installed.

Selection of AC-side photovoltaic SPDs

• Photovoltaic Inverter: A device that converts DC power (batteries) into AC power. On the AC side of the inverter, a plug-in modular photovoltaic-specific Level 2 AC SPD is typically installed;

• Main Distribution Box: The AC power output from the inverter needs to be fed into the grid or directly supplied to the load. Near the direct lightning area, a Level 1 AC photovoltaic SPD should be installed at the main distribution box.

When selecting photovoltaic SPDs, we must remember the importance of protecting the entire system from lightning and surge voltage impacts. By providing appropriate protection for photovoltaic components, inverters, and other critical equipment, we can extend the system's lifespan, reduce maintenance costs, and make a greater contribution to the promotion and utilization of clean energy.