Will solar panels work after an EMP?

An electromagnetic pulse is a phenomenon that can fry electronics across a wide area. Solar panels are often in the kit of anyone planning to survive the next zombie apocolypse or other crisis. But will they still work after an EMP?

Photo of aurora borealis
Credit: Unsplash

An electromagnetic pulse (EMP) is a burst of electromagnetic energy. Like any magnetic field it’s invisible, but if it’s powerful enough it can knock out electronics or even the power grid.

This happens because a moving magnetic field can generate an electrical current in a conductive wire. In fact, this is how a generator works. If you take a really big moving magnetic field and apply it to a really big wire - such as the transmission wires of the electrical grid - the resulting surge of electricity could be large enough to cause widespread damage to power plants, electrical substations, and other major infrastructure.

Smaller equipment can be affected too, especially anything with electronic components. Computer circuits might be designed to handle only a few milliwatts of power, so it doesn’t take a lot of excess power to destroy modern devices. It’s not just obvious things like laptops and smartphones, but your car and appliances all have circuit boards in them.

How about solar panels? Parts of a solar panel system can be affected by an electromagnetic pulse. A grid-connected solar array will be knocked offline if the grid is disabled by an EMP. Off-grid systems can be impacted too, but it is possible for a solar panel system to continue to work even after an EMP.

Read more to learn how you can ensure that you have solar electricity available during this type of emergency, but first let’s learn about what an EMP is and how it can happen.

What is an electromagnetic pulse?

EMPs actually happen all the time on earth. They can be generated by lightning, which is a surge of electricity that creates a brief magnetic field. Known as a lightning electromagnetic pulse (LEMP), these are usually too small to cause a problem.

The kind of electromagnetic pulse to worry about are those large enough to cause large scale disruptions. There are two kinds: natural phenomenon and artifically-created EMPs.

What is a coronal mass ejection?

Naturally-occuring EMPs large enough to worry about are caused by space weather. One type is a coronal mass ejection (CME), which is a flare on the Sun’s surface that releases a massive amount of charged plasma into space.

If the CME happens to be pointed at Earth, it can crash into the magnetosphere and cause a surge of magnetic energy. If the CME is large enough, the resulting magnetic field can be large enough to damage equipment on the ground and cause widespread blackouts.

The Sun throws off plasma on a smaller scale frequently. This results in aurora borealis, also known as the Northern lights. Aurora might cause minor disturbances on the ground, such as radio interference, but don’t cause significant damage.

Coronal mass ejections are much more rare. The only one on record was known as the Carrington Event, which happened on September 1, 1859 - before the electrification of the industrialized world. Telegraph systems did exist, and the EMP effect was large enough to give telegraph operators strong electric shocks.

If the Carrington Event happened today, the damage could be extremely widespread and destructive, knocking out major infrastructure such as transformer stations and the global positioning satellites. According to experts, it could take years to recover from this type of event.

EMPs caused by nuclear weapons

EMPs can also have a much more sinister cause: a nuclear detonation in the atmosphere. While this has never been used in war, a nuclear explosion dozens of miles high in the atmosphere could generate a pulse of gamma radiation that would in turn generate a large amount of electromagnetic energy.

This was first observed during nuclear testing in the late 1950s. One test known as Starfish Prime, which involved a 1.4 megaton nuclear explosion, created an EMP so strong that streetlights in Hawaii were knocked out - a distance of more than 900 miles away.

In theory, a nuclear-capable nation that wanted to destroy critical infrastructure without causing Hiroshima-type destruction on the ground could deploy a nuclear weapon with the intent of generating a massive EMP.

Can solar equipment survive an EMP?

If you have a grid-connected solar array, there’s little point in worrying about whether your solar equipment will survive. When the grid is down, the inverters in a grid-connected solar array will shut down too.

However, it’s possible to stay powered while off the grid using batteries. That means if you’re preparing for an EMP, a zombie apocolypse, or other doomsday scenario, an off-grid capable solar array with battery storage could potentially keep you supplied with electricity after the doomsday event.

Solar panels don’t have electronics in them. They consist of silicon solar cells, wiring, and a junction box that has some diodes - no circuit board with delicate electronics. Your solar panels should survive an EMP just fine.

However, other components in your system may not fare so well. Inverters and charge controllers are electronic components that could be destroyed by an EMP.

If you have a modern lithium-ion battery system such as a Tesla Powerwall, it has a lot of smart electronics built into it. So while a battery is necessary to keep you powered off-the-grid, these smart batteries might also get fried in an EMP event.

What can you do? If you really want to design an off-the-grid solar system that will keep you powered after an EMP, it is possible.

First, you need a dumb battery bank without built-in electronics. While there are some lithium-ion products, lead-acid batteries are still a common choice for this especially for marine or RV applications. Lead-acid batteries are heavy, have no electronics, and will survive any EMP.

You will still need a charge controller and inverter. A Faraday cage could protect these devices, but if they’re connected to the solar system they might still be damaged. The best way to ensure that you have working devices is to keep offline spares inside a Faraday cage.

Should you really worry about an electromagnetic pulse?

Catastrophic scenarios like a large-scale EMP can be frightening. If you’re a solar homeowner, should you take steps to protect your system and increase the chances of having electricity after such an event?

I don’t think so, for two reasons:

  • The chances of either a natural or non-natural EMP occurring is very low.
  • If such an EMP does happen, you’ve got bigger problems anyway.

The Great Toilet Paper Scare during the COVID pandemic demonstrated that our global economy is very interconnected and perhaps more fragile than we realized. If a wide-scale disruption from an EMP were to happen, keeping the lights on in your house would be helpful, but there will also certainly be supply disruptions for all kinds of goods and services - things more critical than toilet paper.

As for a nuclear EMP, The National Interest calls the idea “fake news on steroids” and argues that if an aggressor were to launch a nuclear EMP, the fact is that the world would be moving toward thermonuclear war, in which case we all have much bigger problems.

That said, many people like to be prepared. If you’re such a person and you either have an off-grid solar array or you’re designing one, it’s not a bad idea to have a spare inverter or charge controller around.

This might be a good idea if you have a remote cabin and a replacement might take a week or more to acquire. If you keep some spares around, you won’t have to deal with any prolonged blackouts.

And as long as you have spare components sitting on the shelf, it costs very little to protect them with a Faraday cage constructed with aluminium foil or other inexpensive materials.

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