Managing the solar eclipse

On the morning of Monday, August 21, 2017, a total solar eclipse will pass over the Pacific Northwest, affecting the California ISO’s solar resources supplying power to the grid. Learn about the challenges of operating an electric grid during an eclipse and how the ISO has prepared for the reduction in sun power. On the day of the eclipse, use the below graphs to chart the drop and restart of solar generation, along with electrical demand in the ISO system.

Eclipse NASA Video
Eclipse NASA live stream Video




Quick links

Presentation - solar eclipse ISO impact analysis.

View the news release.
ISO Adds Teleconference Information to Eclipse Media Availability.
Click here to get answers to frequently asked questions.
Click here to watch video recording of Aug. 10, 2017 Solar Eclipse Informational Call.
Read about the western EIM’s management plans.
Learn how to safely watch the eclipse.

Solar production 

Graph shows aggregated output from solar connected to the ISO grid.

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Graph displays current system demand plotted against forecast demand.
Actual Demand displays instantaneous maximum MW amount over previous 10 minute period. 
Forecasts are hourly average MW. 

Today's Demand​

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Net Demand

The net demand curve depicts the variability in demand and supply that the ISO must counter balance to maintain grid reliability. Net demand is calculated by taking the actual demand and subtracting the electricity produced by variable generation resources, wind and solar, that are directly connected to the ISO grid.

Higher levels of variable electricity generation increases the ISO operational need for resources with the technological flexibility to start and stop quickly, and maintain output for set periods of time, so we can match supply and demand at all times.  

Click here to learn how flexible resources help renewable integration.


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