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June 2019  •   Issue 20
As a federally regulated nonprofit organization, the ISO plans and operates the state's high-voltage electric grid and "keeps the lights on" for California and a portion of Nevada.

ISO’s 2019 Summer Assessment outlines electricity outlook


The California Independent System Operator (ISO), in its 2019 Summer Loads and Resources Assessment, predicts an adequate amount of power supplies to meet summer demand largely because of this year’s above-normal hydropower resources.

However, the report found the ISO’s greatest operational risk will occur in the late afternoons when solar production drops and demand rapidly increases. The report also highlighted that uncertainty surrounding Southern California’s natural gas system will continue to impact energy reliability in the region.

Although the ISO faces a higher potential for shortages during rising late afternoon demand, the 2019 assessment showed an overall “low probability of a system capacity shortage” for the months of June through September, with the 2019 peak demand forecast at 46,511 megawatts (MW), and 51,765 MW of available system capacity in place for the season.

The above-normal snowpack and major statewide reservoir storage levels will also provide the system with increased hydroelectric support throughout the summer season.

The positive forecast of summer electricity conditions could lead to a reduced need for Flex Alerts, the program that calls for consumers to voluntarily conserve during times of tight supply. However, consumers are still encouraged to participate in conservation practices when possible during the upcoming season.

For more information on the assessment, read the news release.

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Flex Alerts: What they are and how they help


Although the ISO's summer assessment predicts sufficient power supplies during California’s hottest months, factors including unplanned power outages, fires that lead to transmission line losses, and heatwaves can all cause shortages of energy supply. During these times of tight supply, it’s important to be prepared to conserve in the event the grid operator calls a Flex Alert.

Flex Alerts are calls for consumers to voluntarily conserve energy during predicted strain on the energy grid. These alerts are most commonly issued when extremely hot weather causes an evening increase in electricity demand, when solar generation is going offline and consumers return home to turn on air conditioners, lights, and appliances. During wildfire season, Flex Alerts will be especially important, as fires can cause transmission line outages.

Although most effective when issued a day in advance of the predicted shortage, Flex Alerts can also be issued with little or no advance notice.

When the ISO calls a Flex Alert, consumers are asked to take the following conservation actions:

  • Set the air conditioners to 78 degrees or higher, if health permits
  • Delay using major appliances until after 9 p.m.
  • Turn off all unnecessary lights

These three conservation actions can be valuable to balancing the power grid. When the ISO issued a Flex Alert last summer, consumers helped save about 1000 MW of energy – enough to power about 1 million homes. The conservation also means that more drastic measures, such as electricity interruptions, are avoided.

To learn more, view energy conservation tips, and sign up to receive Flex Alert notifications, visit

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ISO launches Summer Readiness webpage


The ISO launched a dedicated Summer Readiness webpage, where visitors can learn more about the ISO’s summer outlook, how consumers can help relieve stress on the power grid when a Flex Alert is called, and find out more about utilities’ wildfire risk mitigation plans.

On the page, users can access resources including the 2019 Summer Loads and Resources Assessment, System Alerts, Warnings and Emergencies (AWE) Fact Sheet, a history of Flex Alerts, the latest issue of the Energy Matters newsletter, and a Summer Readiness Fact Sheet.

Also located on the page is a link to the Flex Alert website, where visitors can learn more about the program, view energy conservation tips, and sign up to receive voluntary conservation notifications.

Visit the page here to learn how to best prepare for the summer season.

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Stay up to date on summer electric conditions


With the summer season comes hot weather, which increases demand for electricity. The ISO has made it a priority to provide the public with resources to stay up to date on energy-related topics.

The ISO constantly updates the following links for the public to view real-time grid conditions:

  • Today’s Outlook – On the ISO’s website, this page allows visitors to track real-time demand and supply, available capacity, forecasted peaks, CO2 emissions, and day-ahead, 15-minute, and real-time wholesale energy prices.
  • ISO Today mobile app – This convenient smart-phone app tracks grid conditions and provides notification for Flex Alerts and System Alerts, Warnings, and Emergencies.

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Help the ISO spread the Flex Alert message


When a Flex Alert is called, the ISO needs help to spread the word. The Flex Alert logo, in addition to web banners, are available on the Flex Alert website to download. The ISO encourages the use of these materials to help share the Flex Alert conservation message on social media and through newsletters or websites.

When a Flex Alert is called, the ISO also provides the public with reminders and updates on its dedicated Twitter account, @FlexAlert, and the ISO account, @California_ISO. Please help by retweeting these reminders and updates to help maximize the reach of the call to consumers for voluntary conservation.

To learn more about the program and to sign up for notifications, visit For conservation tips, and Flex Alert reminders and updates, follow Flex Alert on Twitter and Facebook.

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