Why People In Europe Are Worried About The Biggest Solar Eclipse In 15 Years


When the moon takes a bite out of the sun on Friday, solar power production will be temporarily devoured.

On Friday morning, March 20, a solar eclipse will sweep across Europe. This rare aligning of the sun, moon, and Earth will cause the standard delays and hazards as onlookers get distracted by the unusual sky and the darkness it casts. But this time around, there is a new cause for concern: solar power.

The eclipse, in which the moon comes between the sun and the Earth, will be most pronounced in Northern Europe, and the bulk of the apprehension is centered on Europe’s solar powerhouse: Germany. At the size of Montana and nearly the same latitude, Germany is an unlikely solar leader, but a concerted national effort to go renewable has put it at the forefront of solar power development. Its 1.4 million solar energy systems account for around a quarter of the solar capacity installed on Earth and solar provides about seven percent of the country’s power.

During 75 minutes in the mid-morning — when the sun’s power is normally accelerating — Germany will instead rapidly lose solar generation.


The last time a solar eclipse of this magnitude happened in Europe was in 1999, when solar accounted for less than one percent of Germany’s power consumption. Since then, the amount of solar photovoltaic power installed in Europe has gone from a marginal amount to over 90 gigawatts. The Brussels-based European Network for Transmission System Operators for Electricity released a report last month stating that this is the first time an eclipse is “expected to have a relevant impact on the secure operation of the European power system.” The organization estimates that a reduction of solar power production by more than 30 gigawatts across the continent is possible.

Animation solar eclipse of March 20, 2015. CREDIT: NASA
Animation solar eclipse of March 20, 2015. CREDIT: NASA

According to analysts at Opower, a software provider for the utility industry, In Germany solar production will fall up to 2.7 times faster than it normally ever does. The ENTSO-E report predicts that solar generation in Germany will plummet at a rate comparable to shutting down 200-megawatts of power every minute for 40 minutes.

Utility operators and industry experts generally agree that countries across Europe will be able to effectively manage the drop in solar power, thanks in no small part to months of preparation. They also agree that the eclipse presents a unique opportunity to study the way renewables interact with the grid as utilities around the world transition to a new, distributed, and renewable-reliant form of energy production. Regulators and grid operators will be observing closely to determine the best way to deal with interconnection, transmission, and generation issues.

The eclipse will be a “stress test” according to Patrick Graichen, executive director of Agora Energiewende, a Berlin renewable energy think-tank, who told the Financial Times that this type of shift is expected to become more common by 2030 as more renewable energy comes on stream.

“So in a way March 20 is a glimpse into the future of our power systems,” he said.

Mark Baldassari, director of codes and standards at Enphanse Energy, a California-based solar technology company, told ThinkProgress he only expects a small decrease in solar radiation to occur in the affected area.


“Weather and clouds will have a larger impact than the eclipse,” he said. “The articles predict a 30 gigawatt decrease in power. I just don’t think the impact will be that great. I’m sure the predictions were based on clear weather across the region.”

The weather is predicted to be partly overcast across Europe on Friday morning, minimizing the severity of the eclipse’s impact.

Jeff Holland, director of communications at NRG Energy, a large, U.S.-based energy company with significant renewable assets, told ThinkProgress that utilities are prepared to deal with the eclipse, which resembles an overcast or cloudy day.

“Software controls the electricity load and it is configured to switch loads between the installed solar and wind to conventional or on-site backup generation, such as diesel or battery power, when the sun isn’t shining or the wind isn’t blowing,” he said.

Aside from coal-fired, nuclear, or gas-fired power plants, these back-up sources could include pumped-storage hydroelectricity, in which water is pumped to a high elevation during times of ample power supply and then later used to create hydroelectric power, or other renewables like wind or geothermal. Taking efficiency and conservation measures such as turning off lights or waiting to do laundry also lighten the load on the grid.

During future eclipses, grid technology will have a much bigger burden to bear as renewable sources proliferate.

As David Roberts at Grist writes, “It makes you wonder, though, how the European grid might handle the next total eclipse, expected in 2026:”

By then, solar power could be up to hundreds, even thousands of installed GW. What happens when an eclipse knocks out not just 30 but 50 or 100 or 1,000 GW? What happens if it knocks out 75 percent of some country’s power for an hour? You’d need a lot of backup to cover for that — from storage, wind, biomass, geothermal, or, if the grid is up for it, power brought in from regions outside the eclipse.

The situation in the U.S. could be the same. 2014 was a big year for solar — it accounted for 32 percent of the nation’s new generating capacity, more than wind or coal. For the first time ever, the utility, commercial, and residential sectors installed more than one gigawatt of solar PV. As leaders get more serious about addressing climate change and the costs of fossil fuels and benefits of clean energy become ever more apparent, solar power’s share of the energy mix will continue to grow.


California, a longtime U.S. leader in renewable energy production, is preparing for this reality by “having a suite of renewables,” according to Albert Lundeen with the California Energy Commission.

“The possibility of outages resulting from a solar eclipse underscores the importance of having a portfolio approach to the development of renewable resources, as California has done,” Lundeen told ThinkProgress, who said the state’s policies have always focused on using diversity to reduce the risks inherent with overdependence on any one source of energy.

“Variable renewable resources like solar or wind can be balanced with other resources like geothermal, biomass, and hydroelectric which can operate much more like a conventional fossil plant in terms of providing reliable, 24–7 energy,” said Lundeen.

This issue extends far beyond the U.S. and Europe: India and China, two of the world’s fastest growing countries, are pivoting heavily towards renewables as air pollution from fossil fuels darken the quality of life in their major urban hubs. China recently increased its 2015 solar installation goal by 20 percent to 17.8 GWs.

Partial and total solar eclipses happen several times a year in varying parts of the world.