What happens when lightning strikes a solar panel?————How to protect your solar installation from lightning

Installing a grounding system is a great way to protect your solar installation in case of lightning. If lightning hits your solar panels, a catastrophic surge can occur. In fact, lightning is the number one cause of catastrophic failures of solar installations. In order to protect your system, you’ll need to install a grounding system. But where do you start, and what do you need to know?


What happens when lightning strikes a solar panel?

When lightning directly strikes a panel, it can melt the panel or inverter. Indirect strikes will induce high voltages into the system and break down conductors, PV panels, and components. They’ll also produce dangerous sparking that could ignite combustible material.

Also, it’s important to note that contrary to popular belief, solar panels do not attract lighting. Putting solar panels on your roof will not increase your home’s risk of getting hit by lightning.

How do I ground my solar installation?

You can’t prevent lightning from hitting your solar equipment, but you can give it a direct path to the ground. Panel frames and mounts should be grounded in order to provide the easiest path for lightning to get to the ground. Grounding is the most fundamental way to protect your system from lightning damage. An electric path to ground will also discharge static electricity that accumulates above ground. We recommend installing your grounding system before or while you are installing the rest of your solar installation.

Grounding fulfills some essential functionalities, including:

  • It drains off accumulated charges so lightning is not highly attracted to your system.
  • If lightning strikes, your ground protection provides a safe path for discharge directly to the earth.
  • It reduces shock hazard from the higher voltage parts of your system.
  • It eliminates electric hum caused by your inverters or motors

Lightning arrestors and surge protectors can also be used to protect electronic equipment by absorbing electrical surges. However, keep in mind that they’re not a good substitute for grounding. In an ideal setup, they function in conjunction with effective grounding.

What are arrestors and capacitors?

Surge arrestors act like clamps in your system. They offer a discharge path to the earth, rather than allowing any electric current to flow through your electronics. Surge arrestors go across live wires and then, if the voltage goes above a certain level, they will direct the higher voltage to ground. Surge capacitors catch high voltage spikes on the AC line that are too fast for the surge arrestor to catch.

Do fuses and breakers protect me from lightning strikes?

No, fuses and circuit breakers do not offer protection from lightning strikes. That is not their purpose. Lightning usually lasts for only a few microseconds - much faster than any fuse or breaker can blow.

What are the different grounding systems?

There are two main grounding system types: equipment grounding and system grounding.

  1. Equipment grounding: This is the more traditional and visible form of grounding. Any metal or potentially conductive materials that are likely to be energized in the system must be grounded. Equipment grounding is known as safety grounding or protective earthing.
  2. System grounding: In system grounding, one of the circuit (current-carrying) conductors is connected to the equipment grounding system and also to earth. This is known as functional grounding. In system grounding, one of the two conductors coming out of the PV system will be grounded, typically the negative wire. System grounding will also include a ground fault fuse to prevent fires within the system from excessive current flowing into the ground.

What are the different grounding types?

You may be familiar with a single metal grounding rod, but there’s a range of other grounding options available.

  1. Single Point Ground: In this scenario, a ground wire connects to a ground rod or ground wire under the electric meter.
  2. Ring Ground: A #2 AWG bare wire is buried a minimum depth of 30" in the soil encircling a structure.
  3. Ufer Ground: In this type, metal bars that are encased in concrete and buried a few feet under ground. This is used when terrain or other physical barriers prevent single point grounding.
  4. Isolated Ground: This is a separate, insulated safety ground wire that connects an equipment cabinet to the nearest ac distribution neutral-ground bond. It is used to maintain isolation from building conduit, which can conduct high frequency noise during an electrical storm.
  5. Halo Ground: This setup consists of bare or insulated wire and runs around the ceiling of a structure and connected to the corners of a buried ring ground.

Is a single grounding rod enough?

Typically, a single 6 to 8 foot ground rod is not enough. You may have to use 2-3 10-foot rods, all bonded together with #6 wire and copper wire clamps. In some cases, you may need to bury lengths of bare copper wire or copper pipe in trenches.

How do I ground my system?

To give you an idea of what a grounding system can look like, here’s a breakdown of what a single rod installation can look like.

  1. First you’ll drive a grounding rod at least eight feet deep into the earth near your solar installation.
  2. Leave around 6” above the ground to properly attach your wiring to the grounding rod. You can typically use a thick, bare copper wire to handle large electric currents like lightning.
  3. Run your wire up your pole mounting system and attach it to a grounding screw.

Wrap the wire around the grounding screw and tighten the bolt. Trim off any excess wire.

How much does it cost to ground your system?

A home lightning protection system can cost anywhere between £350 and £1,800. The system consists of one or more lightning rods, a grounding system, wiring, and a surge protector. We recommend reaching out to local professionals who are skilled at providing the highest level of protection to solar installations.

Conclusion

We typically don’t expect lightning to have an impact on our lives, but it only needs to happen once for it to create permanent damage to your solar installation. By installing a grounding system, you’ll keep your solar investment