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GE Global Research

Behavioral Science: Solar Eclipses Are Predictable. The People Watching Them? Not So Much

Tomas Kellner
August 21, 2017
Millions of people will step outside today to watch as the “Great American” solar eclipse cuts across the United States from Oregon to South Carolina. But a group of experts responsible for generating and distributing power around the country will keep their eyes glued to their gauges and dials. For them, the show will begin when the shadow passes.
“The one thing that’s very hard to predict is how people will change their behavior because of the eclipse,” says researcher Kathleen O’Brien, who studies electric power at GE Global Research in Niskayuna, New York. In 2015, for example, a solar eclipse that swept over the U.K. led to one of the biggest power surges on record: Overcast skies made as many as 10 million Brits head indoors and watch the event on television, according to The Telegraph.

Although a total solar eclipse lasts just a few minutes, it can dramatically affect solar power generation. The 2015 event, for example, forced German engineers to ramp up conventional power plants to compensate for the fast drop-off and rise in power supplied by the country’s plentiful solar farms. Some called it a “stress test” for the grid.

By now, there are plenty of solar panels in the U.S. as well — the industry has grown 68 percent every year over the last decade to nearly 45 gigawatts in installed capacity. We spoke with O’Brien about the impact of the event on your power supply.

 width= “The one thing that’s very hard to predict is how people will change their behavior because of the eclipse,” says GE researcher Kathleen O’Brien. Images credit: Getty Images.

GE Reports: Much of America will be staring at the sun today, but you have been thinking power plants. Why?
Kathleen O’Brien: Look, utilities have obviously known that this was coming and they are ready to go. It’s really not a big deal. Utilities know how much solar power they’ll get on a daily basis, and some can make precise forecasts as close as 15 minutes ahead. They know early enough to turn on a gas turbine when the load will be coming off a solar farm. Even if there is not enough gas in South Carolina, they can move power from New York or anywhere else. The one thing that’s harder to predict is how many people will change their behavior because of the eclipse.

GER: Just like in the U.K. two years ago?
KO: Yes. Millions of people suddenly went inside, turned on their TVs and teakettles and caused a huge spike in demand. It’s easy to say that the sun is going to go away and that it’s going to get dark. But getting the big picture right is much harder. Even though the surge in power after the U.K. eclipse was larger than expected, the grid operators were still able to handle it and no one lost power. That shows just how resilient a modern power grid is to handling unexpected events.

GER: The eclipse can change the big picture very fast in unpredictable ways.
KO: Exactly. Utilities typically look at past patterns to do load forecasting. They know well what the load is going to look like on a sunny Tuesday in August. They can factor in a major game taking place that day and other planned events. But something like a total eclipse that crosses the entire country almost never happens.

GER: There’s no way to benchmark our collective behavior during the eclipse.
KO: Right. Utilities know precisely what the moon and the sun are going to do, but they don’t know what you and your friends will do. That’s what I would be focusing on if I were in the power-generation business.

GER: How are utilities responding to this uncertainty?
KO: They will likely turn on more traditional power plants and fast natural gas generators than they would otherwise do to soak up any extra demand. Since the eclipse is on a workday, they can also call factories to reduce their power needs, say, by turning down their air conditioners and other power-hungry industrial systems. Typically, they have contracts in place that allow them to do that.

GER: Besides hiding behind the moon, what other pranks can the sun play on the grid?
KO: Solar wind can cause geomagnetic storms that can affect satellite communications, cell phones as well as power transmission, especially in higher latitudes closer to the earth’s poles. The solar winds are charged particles that escape from the sun’s corona and slam into the earth’s magnetic field. The corona is the ghostly glow you can see around the darkened sun during a total eclipse like the one today.

GER: Has that happened?
KO: Oh, yes. In 1989 a solar storm caused a blackout in Quebec. It made voltage in the transmission system fluctuate so violently that it triggered the safety mechanism and led to a nine-hour blackout. The utility, Hydro-Quebec, now has a system in place to mitigate the sun’s effects. In fact, utilities in the northern U.S. and Canada have task groups to deal with the problem.

GER: Are you going to watch the eclipse?
KO: Definitely, although where we are in New York state, we won’t see the total eclipse. There is a lot of excitement among us geeks. One of my colleagues is an amateur astronomer and he ordered special dark glasses for every single person in our group so we don’t burn our retinas. Last time I saw the eclipse I was in sixth grade. I am really looking forward to it.