Monday's total eclipse is the first in 26 years when there was less than 5 megawatts of installed solar capacity. Now there is almost 43,000. 

While millions of Americans were outside looking up at Monday’s total eclipse, hundreds of IBEW utility members kept the lights on as the sky goes dark.

As the moon’s shadow raced from Oregon to South Carolina at more than 1,000 miles per hour, nearly half of the nation’s solar capacity fell into at least partial shadow. Nearly 9,000 megawatts will disappeared from the grid.

In a rippling wave from coast to coast, demand for power increased as lights come on in the partial darkness and all the homes and businesses that rely on roof top solar turned to the grid at once.

And unlike the celestial spectacle, there was next to nothing to see.

The electric grid didn’t fluctuate even a small amount. The country lost and then regained the equivalent of 15 coal power houses and the lights stayed on, air conditioning compressors still fired up and complex industrial equipment that relies on precise voltages worked flawlessly.

“We can handle it because of our diversity in generation,” said Utility Department Director Donnie R. Colston. “Our gas, nuclear and coal plants run whenever we need them: rain, sun and even total eclipse.” 

Most of the solar generation facilities in the U.S. are out of the path of the totality eclipse, but will still see a dramatic fall in generation,
especially in California. Only source diversity including, coal, hydro, nuclear and natural gas will make up the shortfall.


And many of them are IBEW built, run and maintained.

The bulk power system in North America is divided into eight regions, and the independent system operators are responsible for keeping their individual electrical grids operating. With the North American Electric Reliability Corporation, they have been preparing for the eclipse for years, and had plans to replace the lost solar power.

California, for example, gets 40 percent of its energy from solar panels. It lost nearly three-quarters of that, and was not even in the direct path of the eclipse. According to the California independent system operator, power output fell by 70 megawatts a minute (a megawatt is enough to run a Wal-Mart Supercenter) and then returned at 90 megawatts a minute, about eight times faster than in a normal day, because after the shadow passed, the sun was more nearly directly overhead.

PJM, the independent system operator for the mid-Atlantic, saw a 2,500 megawatt increase in demand for nonsolar generation during the hourlong peak of the eclipse even though, like California, it was out of the path of the total eclipse. At most, the southernmost parts of PJM saw 90 percent blockage. Unlike California, however, that represents less than 2 percent of total load.

Until there are significant advances in energy storage, intermittent, renewable energy generation will challenge the reliability of the grid. When a switch is flipped, customers want the light to go on, whether there is cloud passing over a solar facility, the wind dies down or an eclipse.

The more wind and solar drive the disappearance of coal and nuclear, the greater that challenge will be. And it doesn’t take a solar eclipse to make that challenge plain.

Total solar capacity in the United States has increased from 5 megawatts in 2000 to 43,000 in 2016. In that same time, gigawatts of coal and nuclear have been shuttered.

When the last total eclipse crossed North America 24 years ago, it passed without a ripple on the power grid. When the next total eclipse crosses North America in less than seven years, it will be a wave.

“The IBEW supports all forms of generation. We install solar panels and wind turbines every day and it is excellent work for thousands of our members,” Colston said. “But we also understand how the electric grid operates. We know that our large baseload plants provide the stability our grid needs to absorb the intermittencies of renewables and even transmission outages. Today is a shining example of how our baseload power plants provide stable electricity 24/7.”