Surge Protection Device for Photovoltaic Application

What is a Surge Protector Device?

A surge protector device is a device that limits the surge current and repeats the same as specified. This is a cost-effective solution that helps prevent downtime, improve the system and data reliability, and eliminate equipment damage through transients and surges. The photovoltaic surge protector is suitable for any type of facility and load 1000 volts or below.

SPD Applications:

• They work in power distribution, control cabinets, electronic motor controllers, equipment monitoring, metering, medical equipment, backup power, etc.
• When it comes to home appliances, you can use surge protector devices in communication circuits, cable TV feeds, security systems, alarm systems, stereo equipment and other appliances in the kitchen or household as well.
• People use it in hospitals, schools, water treatment plants and also telecommunication facilities.
• They help avoid utility switching and the switching of electric motors.
• In addition, they help in connecting computer devices to a single source of power.

Before the introduction of search protection devices, people utilize coils, motors, resistors, etc., to protect the equipment from any surge. However, when the new devices came into the market, new technology for this purpose also arose. Two devices that are the surge protector and the surge arrester, later came into existence. They protect the wires, transformers, and various equipment from lightning. Also, they are responsible for maintaining the voltage below the insulation level. They both work in the same way with minor differences.

Photovoltaic Surge Protector

A surge protector will perform the inexpensive equipment usually used at home or office and even hospitals or other critical areas. However, when you consider large equipment like transformers for protection, surge arresters are a better choice. Search protectors are getting famous rapidly because of its features and very high capability of protecting expensive equipment from surges. The use of surge protection devices has increased continuously by almost 20% every year. Many manufacturers use it highly in service entrance, and to make a clean supply of power etc.

According to the National Electrical Code, the Designs of the Surge Protectors are as Follows:

• Type 1: the main purpose is to protect the electrical system’s insulation levels against the external surges that might be caused by lightning or bank switching.
• Type 2: The Main purpose will be to protect the sensitive electronics and microprocessors. They protect the base loads against lightning energy, and motor generated surges, and other surge events are generated internally.
• Type 3: You can use it as a point of utilization SPDs installed at a minimum conductor of 10 meters in length farther from the service panel to the point of utilization.
• Photovoltaic systems have unique characteristics that require surge protector devices that are specifically designed for PV systems.

They have huge DC system voltages that reach up to 1500 volts. A photovoltaic system includes all the components and subsistence to convert solar energy into electrical energy to connect to a utilization load.

SPDs for the DC side of Photovoltaic systems: The characteristics of photovoltaic systems differ a lot from traditional DC sources. PV sources have a non-linear characteristic which leads to long-term persistence when it comes to ignited arcs. Hence, PV current requires larger switches, fuses, and requires a disconnector for the SPD. This disconnector is then adapted in a unique nature to cope with the PV currents.

When you install SPD on the DC side, you can specifically make it for DC applications only. The use of the device on the incorrect side will lead to hazardous conditions.

SPDs for the AC Side:

Surge protection is as important for the AC side as the DC side. You must ensure that you design SPD especifically for the AC side. It should fit the size according to the system. Based on the proper selection, the protection will last longer. Multiple inverters can be connected to the same SPD on the AC side as long as they share the same connection of the grid.

The installation of SPD will rely on three values:

• The SPD will activate the voltage.
• The category of the equipment’s overvoltage should be higher than the protection level of the SPD’s voltage.
• The value of the peak waveform that the SPD will be capable of withstanding after several surges.

How to combine SPDs with inverters?

Photovoltaic systems consist of highly sensitive equipment that requires a lot of protection. Because PV systems create direct power, inverters are an essential part of this production. However, inverters are not only very expensive, but they are also susceptible to lightning strikes.

If the system inverter goes ahead 30 m from the nearest combiner, they require additional SPD at the DC input. If string protectors like fuses are available, the you can install SPD between the fuse and the inverter. However, it is important to ensure that the fuses inside I will buy fast and the external fuses are also connected.

The SPD should be mounted outside the inverter in an enclosure or higher if the application is outdoor. If the inverter has multiple MMP trackers, then you must plan the combination of the surge protection device ahead of installation. For inverters with only one MPP tracker, we should combine the string ahead of the inverter and connect it to the SPD at the point of intersection. Also, when you are using other PV products, you must be careful combining the string and the SPD.

The operation of photovoltaic equipment without the use of a surge protection device is very risky. The currents of lightning is inevitable; hence protection is very important. The vulnerability of the photovoltaic systems when it comes to lightning is direct and indirect, which means that it should be built with reliable products and properly installed with search protection.