Do solar panels increase the risk of a lightning strike?

We’ll address the myth that putting solar panels on your roof puts your home at greater risk of lightning strikes.

Photo of a lightning strike.

There’s a lot of myths when it comes to lightning, such as lightning never striking the same place twice, or that using an umbrella in a storm puts you at greater risk of being hit by lightning.

It’s understandable: lightning is a mysterious force of nature to many, and it’s also destructive, causing over $1 billion in property damage in the United States every year.

When it comes to solar panels, there’s one persistent myth, which is that putting solar panels on your home can actually attract lightning to your home.

Right off the bat, I’ll give you the answer: no, lightning isn’t attracted to solar panels, and putting solar panels and the metal racking it requires on top of your roof doesn’t increase your home’s risk of getting hit by lightning. That said, there are some general things that you as a homeowner might want to know about lightning, and how to protect your home. First, let’s cover some basics about the science of lightning.

Lightning risks for the homeowner

Lightning is a discharge of static electricity from a thundercloud. It can transfer as much as one gigajoule of energy, equivalent to one million BTUs of heat energy. A lightning strike that hits a structure can ignite fires and cause severe structural damage.

Your overall odds of personally being struck by lightning are very low: less than one in a million. Still, with the number of storms that occur across the United States, there are a couple dozen fatalities due to lightning in any year.

While the overall risks are low, there are some parts of the US that experience many more thunderstorms that others. In particular, the Southeastern US sees more lightning strikes than other parts of the country.

If you’re a homeowner living in one of these areas, you might want to know how to protect your property. Also, if you happen to be a solar homeowner, or you’re thinking of becoming one, you might wonder if there are special considerations for rooftop solar.

With respect to the latter, I mentioned above that solar panels don’t attract lightning or increase your risk of being hit. Here’s why.

Dispelling myths about lightning

There are a lot of old wives’ tales when it comes to lightning. For solar homeowners, here are a few myths to dispell.

Fact: Lightning isn’t attracted to metal

Lightning can strike any object: trees, water, the ground, or rocks. Whether or not an object is an electrical conductor doesn’t matter. Here’s what has to say about this:

Height, pointy shape, and isolation are the dominant factors controlling where a lightning bolt will strike. The presence of metal makes absolutely no difference on where lightning strikes. Mountains are made of stone but get struck by lightning many times a year. When lightning threatens, take proper protective action immediately by seeking a safe shelter - don’t waste time removing metal. While metal does not attract lightning, it does conduct it so stay away from metal fences, railing, bleachers, etc.

So if lightning isn’t attracted to metal, you might wonder how lightning rods work. On a home, lightning rods are the pointy part of a home lightning protection system, and they can prevent damage to your home if it gets struck.

A lightning protection system works because it’s a preferential pathway for the lightning. In other words, while a lightning rod doesn’t attract lightning to your home, the highly conductive pathway is has to the ground presents an easier route for the lightning to flow. The lightning will choose that easier path, and flow along the thick wiring of the lightning protection system, protecting the rest of your home’s structure.

Fact: The electricity in solar equipment doesn’t increase lightning risk

Lightning is a discharge of static electricity that equalizes the electrical potential between two objects. Basically: a thundercloud carries a static charge, just like a person does when they rub their feet on a shag carpet. A bolt of lightning between two objects with different charges, such as two clouds or a cloud and the ground, equalizes the charge between them.

Solar panels don’t generate static electricity. Instead, they create current electricity, which is an electrical charge that flows along wires. Properly installed and operating solar equipment will never build up a static charge, which is why you can touch the metal frame of a solar panel and not get shocked.

In any case, solar panels will generate very little electricity under the thick cloud cover of a thunderstorm.

Facts about lightning and solar panels

Now that we’ve gotten a couple big myths out of the way, let’s talk about some practical considerations when it comes to solar panels.

Home solar systems and grounding requirements

According to Article 690 of the National Electrical Code, a home solar panel system must be grounded. This means that a wire must be connected to the metal racking of the solar array and run down to a grounding rod that is placed several feet into the ground.

The primary purpose of the grounding to protect against arc faults, which in extreme cases can cause a fire. An additional benefit is that grounding will prevent any static charges from building up.

This type of grounding is also how lightning rods work, but you shouldn’t count on your solar panel grounding system to protect either your home or your solar panels from damage in the rare case of a lightning strike.

The grounding system of a solar panel system is intended to handle arc faults in the system (due to damaged insulation, for example) which might involve a few dozen amps of current at a few hundred volts, but a lightning strike can carry around 30,000 amps of current at millions of volts. To handle that kind of massive electrical current, you would a dedicated lightning protection system.

Home lightning protection systems can cost thousands of dollars

According to HomeAdvisor, a home lightning protection system might cost anywhere between $389 and $2,310. The system consists of one or more lightning rods, a grounding system, wiring, and a surge protector on your home electrical system.

It’s pretty expensive, which is one reason why you don’t commonly see these installed on homes.

And because of the complexity, it’s usually not a DIY installation, especially when it comes to installing a whole house surge protector at the electrical panel.

If you own a solar farm, you actually do need to think about lightning

While a homeowner who puts a few solar panels on their roof doesn’t need to be overly concerned about lightning, it’s a different story if you own a giant solar farm.

A large home solar panel system might have a dozen kilowatts of generating capacity, but the largest solar farms in the world are massive - more than a gigawatt in generating output or about a million times larger than a home system. For example, the 579 megawatt Solar Star installation in California covers 13 square kilometers!

When you have a solar farm that huge, lightning strikes become much more likely. And again: that risk of lightning is not because solar equipment is metallic or electrical in nature, but simply because its sheer size covers more land, increasing the odds of being hit.

To protect from lightning damage, large solar farms use specialized lightning rods.

Summary: worry about lightning only if you’re at higher risk

Lightning is definitely a risk to homeowners, but adding solar panels to your home doesn’t change that risk. Whether or not lightning is something you should be concerned about will be determined by other factors.

To learn more about lightning risks and safety, check out the resources below.

Further reading

#Myths #Safety #Weather

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