Skip Ribbon Commands
Skip to main content
Sign In

June 2018  •   Issue 14
The ISO is a nonprofit public benefit corporation that manages the bulk electric market, and the flow of electricity over the high-voltage, long-distance power lines for California and a small part of Nevada.

ISO’s annual 2018 Summer Assessment shows potential for energy shortages


The California Independent System Operator (ISO) forecasts tight electricity supply margins during high-use times this summer, especially during evening hours of hot days. The increase of renewable energy sources coupled with reductions in hydroelectric supplies and natural gas plant retirements poses a strain on energy supplies.

In its annual 2018 Summer Loads and Resources Assessment released in May, the ISO predicts conditions to become challenging in the evening hours, as California’s abundant and growing solar supply declines during sunset, at the same time consumers return home from work and turn on air conditioners and other appliances.

In fact, the 2018 analysis found a 50-percent probability that the ISO will need to declare a Stage 2 Emergency for at least one hour this summer, which hasn’t occurred since 2007. The report shows an extremely low probability of rotating power outages.

Read more of the Energy Matters newsletter to learn how you can help during periods of tight energy supply. Click here to view a news release on the assessment, including a link to the report.

back to top

ISO may call more Flex Alerts this summer


Because of high energy use and potential for tight electricity supplies this summer, the California ISO may have to ask for the public’s help by declaring more Flex Alerts to ease stress on the grid this summer. The number of Flex Alerts may be higher than past summers, based on the grid operator’s 2018 Summer Assessment.

Flex Alerts are voluntary calls to consumers to reduce electrical use. Consumers are asked to take conservation actions, such as setting air conditioner thermostats to 78 degrees or higher, delaying use of major appliances until after 9 p.m., and turning off all unnecessary lights.

Consumers have responded to past requests for conservation, shaving as much as 500 megawatts (MW) of energy during the evening rush for electricity. The savings are helpful when considering that 1 MW of electricity powers about 1,000 typical California homes.

With summer just around the corner, consumers can get prepared for the heat by signing up for Flex Alert notifications. Go to to learn more about the program, sign up to receive Flex Alerts, and get energy conservation tips.

Click here to visit the ISO’s “Today’s Outlook” webpage and see real-time energy supply and demand conditions.

back to top

Demand Response: How can it help?


Besides Flex Alerts, the ISO has another valuable tool it can use to help alleviate strain on the grid. The operator can issue a warning or emergency, allowing the ISO to call on a pool of Demand Response resources bid into the market.

Participants in Demand Response programs essentially agree to reduce electricity use during tight supply conditions, in exchange for rate discounts or incentives.

The customers can be large manufacturing plants that reduce energy use and make it available in the market, creating a pool of about 1,000 megawatts; or smaller commercial and residential customers who sign up with their local utilities for load reduction measures, such as air conditioning cycling and turning down agricultural pumps.

The ISO starts the process of accessing Demand Response resources by issuing a Warning, Stage Emergency, or Transmission Emergency. Using Demand Response will be an option this summer for the ISO to meet demand during peak loads, and prevent the need for further actions, such as using its operational reserves or ordering rotating power outages.

To learn more about Demand Response, visit the California Public Utilities Commission (CPUC) website here.

back to top

Monitor electricity trends, learn about system alerts


With summer on its way, the ISO offers many ways for the public to become educated and engaged with energy demand, supply, and resources. The ISO website at is full of information on the summer outlook, system alerts, renewable energy, emissions, and more.


  • Visit the ISO’s Today’s Outlook webpage to watch real-time demand and supply, wholesale energy prices, and emissions data.
  • Visit the ISO’s Alert, Warning, and Emergency webpage to learn about the different declarations and notifications.
  • Download the ISO Today mobile app for notifications and grid conditions.
  • Visit the ISO’s Key Topics page for vital reports.
  • Visit the ISO’s News page for media resources and contacts.

back to top