En kraftig solstorm kan føre til total blackout. Oppsiden er nordlys, som dette over Tromsø en kveld i 2022.
Powerful solar storms can result in total electricity blackouts. The upside of such storms are northern lights – perhaps even as far south as Florida, USA. Here we see the aurora illuminating the skies above Tromsø in 2022.

A solar storm can render your phone useless

Solar storms are no joke. It may get cold and it may get very dark. Our mobile networks may be severely disrupted.

Kristian Solheim Thinn is interested in something happening 400,000 kilometres away. He is a research scientist working with electrical power components at SINTEF Energy. 

During a solar storm, electrically charged particles and magnetic fields are ejected from the sun. This low-frequency current can pass through our transformers and damage the power supply.

“The only real protection from solar storms is to switch off the electricity. If a major storm occurs, we must either live with it and hope that our distribution grids will not be severely damaged, or simply prepare for the fact that we will all be without electricity. These are the two extremes,” he says. 

Vulnerable transformers

Ogndal is a former municipality in what used to be knwon as Nord-Trøndelag county, located in Central Norway.
Ogndal is a former municipality in what used to be knwon as Nord-Trøndelag county, located in Central Norway.

In 2019, the researcher installed sensors in a transformer in Ogndal in Central Norway to measure and analyse what happens when solar storms collide with the Earth’s magnetic field, creating problems for all of us. Especially in northern latitudes where the magnetic field offers far less protection than at the equator. Solar storms create what is called geomagnetically induced currents (GIC).

It was no coincidence that the transformer at Ogndal was chosen. Since the distance between neighbouring transformers is so great, it is easier for solar storms to create problems.

“We are currently as well prepared as we can be. Overhead cables are resilient in the face of solar storms, but transformers represent the weak link in the chain. In Norway, our transformers are connected to the main distribution grid, operated for the most part by Statnett. They are grounded, which means that any current induced in the cables passes through the transformers and out into the ground. This creates no problems at lower voltages. However, things are very different during solar storms,” Thinn says.

He explains that transformers in Norway are designed for alternating current. So, when direct current is geomagnetically induced during solar storms, the transformers may start to generate internal heat. This results in increased, or so-called reactive, power consumption that disrupts the distribution grid. This then causes high frequency noise that may result in problems for the control system. Eventually, the transformer cores may become what is known as ‘saturated’.

"This in turn causes safety mechanisms to disconnect the transformer, hopefully before it is badly damaged," he says. 

But it doesn’t end there. If one transformer is in trouble, the next in line has to take over, which means the second transformer must carry twice the load. This might be too much to handle, leading to its failure as well – and in this way a domino effect will develop.

 “In the worst case, we’re talking about a total blackout,” Thinn says. 

Researcher Kristian Solheim Thinn mounting sensors on a transformer in Ogndal in Central Norway. The aim here is to find out what problems solar storm-induced current causes for electricity consumers.

First of all, it will start to get cold

This is why the grid operates under a number of precautions. In 2019, the Norwegian Directorate for Civil Protection (DSB) compiled a list of things that could go wrong here in Norway. The list includes issues such as the impacts of extreme weather events, flooding, pandemics, cyberattacks, and not forgetting the mother of all catastrophes – solar storms, which were classified as a real threat.

It’s patently obvious that there isn’t a lot we can do about solar storms. We have anywhere from 18 to 72 hours to prepare for something that cannot be stopped.  Researchers will only find out how big a solar storm is one or two hours before it strikes the Earth. They can arrive very suddenly.

A recent SINTEF report reveals that there is currently no Norwegian system for solar storm warnings.

“The upside is that during the most intense storms we will get to see some fantastic displays of the northern lights, even as far south as Florida,” Thinn says.

The downside is that the impact will be felt for many long months afterwards. Satellite navigation could be knocked out. This would create major problems for traffic on land and sea. Low-frequency and high-frequency radio transmissions will cease, and you will not be able to refuel your car. 

“Petrol pumps also rely on electricity. After two hours, the batteries at the base stations supporting the mobile network will run out. We will then lose mobile coverage and things will really begin to go downhill,” he says.

First of all, it will start to get cold.

DBS recommends that everyone follows their advice on self-preparedness for emergencies. Nine litres of water, two packets of crispbread, a pack of porridge oats, three packets of dried foods or tins, per person, as well as warm clothes, blankets, sleeping bags, and a battery-powered DAB radio.

The solar storm of 1859

One of the most famous solar storms in recorded history was the Carrington Event of 1859. It is named after the British astronomer Richard Carrington who observed some intense sunspots.

“The event occurred during one of the famous Californian gold rushes, and one urban myth suggested that the light was so intense that miners were able to pan for gold at night. The telegraph lines glowed red in the dark and the terminals caught fire,” Thinn says.

In 1921, we saw evidence that solar storms could create problems even when technological infrastructure was in its infancy. During the three days the solar storm raged, electrical fires broke out all across the world. The worst examples were in New York. Trains were brought to a standstill, so the storm became known as the New York Railroad Storm.

 In 1972, a solar storm detonated several thousand sea mines along the coast of Vietnam.

"This was the first time problems with satellites were reported," he says. 

In 1982, problems with as many as four transformers and 15 power lines were recorded in Sweden. This event also caused disruptions in Norway, but no blackouts occurred.

 In 1989, a solar storm caused a nine-hour power outage in Quebec, Canada.

 “We also experienced solar storms in 2003, 2017, and most recently in 2022, when the company Space X lost 40 of its satellites,” he says.

According to the New York Times, the storm cost Elon Musk about 100 million USD.

Things could have been much worse. In 2012, a solar storm barely missed us. Had it hit the USA, it would have caused damage in the region of 20 trillion USD, equivalent to twice the Government Pension Fund of Norway. 

The unpredictability of space

 The researchers have installed sensors in the transformer at Ogndal in order to take measurements and calibrate their data models.

Several factors have to be considered, one of which is solar activity, which is not too difficult to monitor. The US Space Weather Prediction Center (SWPC) can tell us most of what we need to know, but there is one problem – the difficulty of making reliable long-term predictions.

The Tromsø Geophysical Observatory has deployed several magnetometers with the aim of measuring the strength of the Earth’s magnetic field. One of them is in Røyrvik, which about 150-160 kilometres away. The magnetometers measure both the natural geomagnetic field and the magnetic perturbations generated by solar storms.

This provides measurements only in real-time, but can also help us to understand how the geomagnetic field is influenced by events in space, including the solar storms that induce currents in our distribution grids and transformers.

“We also have to know about the electrical conductivity at depths of several hundred kilometres below the Earth’s surface. This is because the geomagnetically induced currents also penetrate deep into the Earth’s crust, and in turn affect the induced currents flowing through the transformers,” Thinn says.

The researcher explains that it is difficult to construct reliable predictive models because the electrical conductivity varies in different layers of the Earth's crust. It is especially difficult to assess the conductivity at the transition between sea and land. The ocean exhibits relatively high conductivity, while the opposite is true for land areas.

“On the other hand, it's not difficult to identify correlations between magnetic field measurements and actual geomagnetically induced currents in our distribution grids, provided that both are being measured at the same time. It's possible to calculate a ratio between these,” he says.

Long seabed cables installed on the continental shelf are very vulnerable to solar storms. One of the studies looked at the effect of shallow offshore continental shelves, similar to that in the North Sea. It showed that the geomagnetically induced current would be three times as strong if there were no sea there.

The researcher has so far found that the so-called electrojets around the magnetic poles mostly travel in an east-west direction in the ionosphere. Other researchers have long thought that solar storms affect power lines differently depending on the direction the current flows.

“It makes no difference at all whether power lines are oriented in a northern, southern, eastern, or western direction. They still remain just as vulnerable,” Thinn says.

The researcher also believes that there is a difference in transformers. In recent years, transformers that can withstand solar storms for a certain period have been purchased. They are designed not to overheat too quickly. It has been shown that three-phase transformers installed with five-limbed iron cores become saturated more quickly than the three-limbed type.

“For this reason, it's now recommended to install three-limbed three-phase transformers in the most important and most vulnerable substation facilities,” he says. 

Approaching a solar maximum

The sun goes through phases of greater and lesser activity distributed over an 11-year cycle. Thinn mentions that in the first two years after the sensors were installed, only very low levels of activity were recorded. However, starting in 2021, and during the remainder of that year, six measurements were made indicating moderate effect activity.

“During moderate effect activity, our transformers will remain resilient, but this may not necessarily apply to the grid,” Thinn says.

On 4 November 2021, a transformer went down at a neighbouring substation in Namsos, about 70 kilometres from Ogndal.

“The safety mechanism was tripped, and this disconnected the transformer. Our findings indicate that there is a connection between reactive power consumption, geomagnetically induced currents, and changes in the magnetic field as recorded by space meteorology instruments. In other words, when we measure strong currents, we observe a simultaneous and major peak in reactive power consumption. If we exceed the safety mechanism threshold value, this trips the transformer’s circuit breaker,” he says.

However, even if a transformer takes a time-out and goes down, as happened in Namsos on that late autumn day, this was hardly noticeable to consumers. This was because other transformers stepped in to do the job. The power grid has reserve capacity, a buffer, which in this case kicked in to avert a crisis.

“However, it was a close call and a stroke of luck that the Ogndal transformer remained in operation,” Thinn says.

In 2024 we will be entering a period in the cycle when solar activity is at its highest. Solar storms are classified on the basis of their intensity. A G1 storm is a minor one, while the most intense is classified as G5.

“We expect to see four G5 solar storm events during every 11-year cycle. The current cycle is expected to display its highest levels of activity in 2024 and 2025. We will most likely experience control and safety issues in the power grid. We might experience a collapse or blackout of the grid, and some transformers may be damaged. We will also experience problems with satellite navigation,” Thinn says.


Thinn, K.S. & Johnsen, M.G. Geomagnetic induced currents in long subsea power cablesSintef Report, 2022.

Thinn, K.S. & Lervik, J.K. 'Proximity effect in high-currenct conductors - a case study of breakdowns in a hydropower plant', Institution of Engineering and Technology. Book, CIRED 2021. The 26th International Conference and Exhibition on Electricity Distribution. DOI: 10.1049/icp.2021.1977 (Abstract) 


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