Solar eclipse:

State regulators have a request during next month’s celestial event — conserve energy.

When a solar eclipse darkens the sky next month, California energy regulators have a small request: Don’t turn on the lights.

Or, if you must, please make sure they’re LEDs.

The Aug. 21 eclipse that will completely block the sun across a wide arc of North America arrives at a time when California is relying more and more on solar power. During past eclipses in the United States, no one had to wonder how the events would affect electricity supplies. Now they do.

The California Public Utilities Commission has created a website, www.caleclipse.org, that asks state residents to pledge to conserve electricity during the eclipse, which will begin just after 9 a.m. and last almost until noon. If they don’t, the state will have to get electricity from fossil fuels.

The organization that manages most of California’s electricity grid insists there’s no danger of the eclipse causing power failures.

The California Independent System Operator, which runs 80 percent of the grid, has been planning for the eclipse since last year. Conservation during the event would be nice but unnecessary.

“We’re confident we’ve got this handled,” said Steven Greenlee, spokesman for the Independent System Operator. “The thing about an eclipse is, it’s very predict-

able.”

While grid managers say the event will be manageable, it does pose a challenge.

California has enough large-scale solar power plants, most of them built within the past five years, to generate a maximum of 10,000 megawatts of electricity. A megawatt is a snapshot figure roughly equal to the amount of electricity used by 750 typical homes in a given moment. Electricity from those plants starts trickling onto the grid soon after sunrise, surges rapidly in midmorning, and hits a plateau around 11 a.m.

The eclipse will strike just as the morning solar supply begins to increase.

The path of total eclipse — where the moon completely covers the sun — will steer north of California, leaving the sun partially obscured throughout the state. But it will still make a difference.

In the Mojave Desert, which has more installed solar power than any other part of the state, 65 percent of the sunlight will be blocked, according to the Independent System Operator’s estimates. In the southern San Joaquin Valley, another region packed with solar plants, sunlight will drop by 69 percent.

As the eclipse deepens, the grid will lose about 70 megawatts of solar power per minute, Greenlee said. By 10:22, production from largescale solar power plants will drop to 3,143 megawatts — almost twothirds lower than normal for that time of day.

Then, as the eclipse passes, solar power production will jump by about 90 megawatts per minute until full sunlight returns. (The rebound will be more dramatic than the dip, because the sun will be higher in the sky.)

Grid managers will not only need to replace the missing megawatts. They will also need to supply more electricity to California homes whose rooftop solar panels will be dimmed by the eclipse.

Fortunately, other grid managers have dealt with this.

In the months before a 2015 eclipse in Europe, analysts wondered how the event would affect electricity supplies. Germany had roughly 40,000 megawatts of solar capacity at the time, raising fears that power fluctuations caused by the eclipse could wreak havoc with the grid.

It didn’t. Chaos failed to ensue.

California officials consulted their German counterparts to glean lessons. One small result: The Independent System Operator has lined up a little extra capacity — about 200 megawatts, from small natural-gas power plants — to have in reserve. (Natural gas produces greenhouse gases when burned, which is why the state utilities commission would prefer not to use it.)

“It is a challenge — it’s something we haven’t seen before at this magnitude,” Greenlee said. “But we have a pretty good idea how it will behave.”