Solar Lightning Protection: PV system grounding and lightning protection

Solar Lightning Protection is important as Lightning strikes and related electric discharge is one of the top reasons for sudden, unexpected failures of Solar systems.

Lighting can seriously harm your PV system

Lightning strikes and related electric discharge are one of the top reasons for sudden, unexpected failures of Solar systems. Solar systems are often installed in open spaces, away from tall structures, and therefore they are more prone to lightning strikes and associated damage. It is a common myth that only a large visible lightning strike within close vicinity of the solar system can cause damage. Also high voltage surges or transient currents, caused by invisible strikes at a large distance from the solar system, may cause damage. You may be surprised that even lightning between the clouds is often sufficient to cause significant damage.

The good news is: damage from lightning can be prevented

By implementing proper system grounding, you can avoid any damage to your sensitive solar system components. Grounding is a technique to connect a part of the system electrically to the earth by means of a conductive material and is the key technique in Solar Lightning Protection. Earth could be considered as a sea of infinite electricity. Any charge/current that is transmitted to the earth is safely absorbed by it. The objective of grounding is based upon the principle of providing a straight, low resistive path for very high currents to reach the earth and get absorbed without causing any harm to equipment or people. Proper grounding is achieved in a number of ways, but the most common technique is by using ground rods.  

How does a ground rod work?

For small solar systems, you can implement grounding by inserting a 8-feet long metallic ground rod, made up of conductive material like copper or aluminum, into the earth. After you connect all conductive parts of the system to this rod with the help of thick wires. For larger systems, it is a good idea to create a grounding grid. A grounding grid is an interconnection of several ground rods, approximately 10 feet apart from each other and connected by the help of a bare copper conductor (minimum size is #6 AWG). Once the grid is formed, grounding is achieved by connecting all conductive parts of the system to the ground grid by means of thick wires. [caption id="attachment_4922" align="aligncenter" width="518"] Solar lightning protection[/caption]

What needs to be grounded?

After understanding the basics of grounding the solar system, it important to understand what needs to get grounded. Not every component need to be grounded by virtue of its mechanical properties. Below is the list of some of the equipment that should be grounded:

1. The aluminum frame of the solar modules.
2. The outer frame of the inverter
3. All the wiring should be grounded. One way of grounding the wiring is by running all the wiring in a metallic conduit and then burying it underground.

Another way, if you are running cable trays to run the cables, is by grounding the cable trays along their entire length.

4. The negative side of the power system.

A note of caution

• In many jurisdictions, provinces and countries, it is a law to have proper grounding of you electrical system.
• When doing any electrical work, there is potential of injury and shock. If you are unsure about your ability to properly wire your system, hire a licensed electrical contractor or electrician.

In many jurisdictions, provinces and countries, it is law to obtain permits and have the wiring done by a licensed electrician or electrical contractor.