The partial solar eclipse slated to take place throughout Europe on March 20 may delight skywatchers, but it’s presenting a significant headache for the operators of Germany’s electricity grid. The country is a world leader in solar energy, boasting a huge edge over the U.S. in installed solar power generation.
When the eclipse occurs between about 9:30 a.m. and 12 p.m., local time, on the 20th, electric utilities in Germany will have to contend with rapid swings in energy production. First, there will be a steep drop-off in generation, followed by a sudden spike.
These fluctuations, and how utilities choose to cope with them, provide a preview of what utilities in the U.S. and other nations face, as renewable energy production soars in coming decades, according to an analysis from OPower, a company that helps utilities and consumers lower their energy use and costs.
Germany gets about 7% of its electricity each year from solar panels, compared to 0.5% in the U.S., according to Barry Fischer, a writer and analyst at OPower. On the sunniest days, Germany can meet half of its electricity demand through solar power alone, he told Mashable in an interview.
Fischer said the eclipse will cause a sudden drop in solar output at a time of day when output typically climbs steeply. After this dip, there will be a sudden, sharp increase in solar output, he added.
The decline in output may be 2.7 times faster than a normal production decline, but solar output would then increase up to 3.5 times faster than normal, immediately after the eclipse ends. “So there’s going to be a slingshot effect,” Fischer said.
The challenge for utilities is to figure out how to keep enough electricity moving throughout the electrical grid to satisfy demand — without incurring high costs, or causing any power outages or surges. “This is a glimpse into the future of the electric grid, a future that has a far greater share of renewables,” Fischer added.
The eclipse will help utilities determine strategies to cope with the intermittency of solar power, which is a problem that is inherent to renewable energy sources. After all, the wind doesn’t always blow, and the sun doesn’t always shine.
Critics of renewables often cite this variability in power output as a reason to invest more in fossil fuel-powered plants, such as natural gas or even nuclear plants, whose output does not vary from hour to hour. However, advances in battery technologies are expected to help offset all or part of the intermittency problem by releasing stored energy at a steady pace, even on cloudy or calm days.
“The eclipse serves to magnify the impacts of the intermittency on the power grid,” Fischer said.
He added that a partial solar eclipse in the U.S. in October led to a 30% to 50% obscuration of the sun across the U.S. In the West, where solar panels are popular among homeowners, panels sent 41% less electricity to the electric grid than normal.
In Germany, the stakes are higher than they would be in the U.S. because it has a much greater reliance on solar power. During the eclipse, average maximum solar obscuration across Germany will be 74%, according to OPower’s analysis, an amount that greatly exceeds the recent U.S. event.
“If it’s a sunny day, we’re going to see a very steep decline in solar output,” Fischer told Mashable.
When solar output decreases, utilities will need to either increase supply, decrease demand or a bit of both. During the spike in output, they will need to turn down power sources brought online during the downturn. “Utilities in Germany are preparing for this, and will draw from a number of strategies,” Fischer said.
Some of these strategies include releasing electricity stored in dams, turning on quick-starting natural-gas power plants, importing electricity from neighboring states or incentivizing reductions in power consumption during particular time periods.
““This event is highly unusual in that the magnitude of the eclipse, combined with the scale of installed solar capacity affected is going to require utilities and grid operators to do things on a scale that they’ve never had to consider doing before,” Fischer said.
“They can overcome this challenge, but it requires planning for the most dramatic impacts.”
In the U.S., research is underway for the construction of a next-generation “smart grid” that would be able to handle the intermittent nature of renewable power plants.
Renewables are becoming an increasingly large player in the U.S. electric sector.
Recently, the U.S. Energy Information Administration (EIA) forecast that in 2015, electric-generating utilities will add 9.8 gigawatts of wind power this year, followed closely behind by natural gas and solar.
The U.S. Energy Department also released a report on Thursday, which found that wind power could supply 20% of the country’s electricity by 2030, a huge increase from the 4.5% it supplies today.
Germany is already facing a more urgent need for such a flexible electric grid, since the country has a target of generating 66 gigawatts of electricity from solar power by 2030, up from the current 38 gigawatts, according to Fischer.
“This is going to be a more day-to-day challenge in the future for areas with a lot of renewables,” he said.
Have something to add to this story? Share it in the comments.