Solar Eclipse May Impact Power Grid

Posted by Tom Denham

May 25, 2017 11:11:53 AM


The first total solar eclipse to darken US skies since the country’s increasing reliance on solar power has soared has forced utilities to draw up contingency plans for a reduction in power during the phenomenon.

As the giant shadow moves west to east on August 21, it will temporarily remove “a large amount of photovoltaic resources” from the country, according to energy experts.



As the event occurs over North America, the eclipse is expected to knock out about 70 megawatts a minute— two to three times faster than the typically daily drop.

To compensate, utility operators are reserving spare capacity from gas and hydroelectric power plants, as well as coordinating with industrial sources to temporarily curb demand.

The expected solar power nosedive means California may need to increase its demand from other sources by 6,000 megawatts, enough power for the city of Los Angeles, as solar output nosedives.

The last total solar eclipse crossed the US in 1979, when renewable technology was in its infancy.

Grid operators already handle supply fluctuations that include glitches from power plants to the effects of cloudy days on solar facilities. This eclipse will result in a rapid decline and rebound in solar power.

The North American Electric Reliability Corporation, a regulatory body, said the eclipse was unlikely to disrupt the continent’s bulk power system but urged utilities to study the impact and monitor generating resources.

US operators are learning lessons from Europe, which had a major eclipse in 2015.  The states most likely to be impacted are California and North Carolina.  North Carolina is the state that is directly in the path of the eclipse.

Duke Energy, the dominant utility in North Carolina, said the company was running scenarios to examine the risks of high electricity demand during the eclipse.