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October 2017  •   Issue 10
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.
First Words A message from the CEO:

Summer 2017 presented a number of exciting challenges to the California Independent System operator. Between record-breaking temperatures and a solar eclipse, our team navigated a number of unprecedented situations.

The world’s eyes turned to California during the Great American Solar Eclipse on August 21, when the solar eclipse dramatically reduced the output of the state’s solar power plants. The ISO’s headquarters in Folsom hosted media from around the globe to watch our grid and market successfully handle the drop and return in solar output. Because the California grid includes the most solar capacity in the nation, our staff spent more than a year forecasting, planning and coordinating with market participants. That planning, coupled with a significant outreach effort by the California Public Utilities Commission to conserve energy, paid off. The eclipse was a smooth event, with virtually no problems thanks to the coordination between the ISO, state agencies, utilities, gas suppliers, and power plant owners.

A record-breaking hot summer also presented significant challenges to the ISO grid. High demand prompted the declaration of four separate Flex Alerts, which are requests for consumers to reduce energy use during times of stress on the grid. Thanks to the Flex Alerts and direct coordination with industry groups such as California Manufacturers & Technology Association, California Farm Bureau, Building Owners and Managers Association of California, etc., conservation from residents and businesses was critical to helping avert grid emergencies and possible service interruptions. The ISO thanks consumers for their much needed help in responding to our calls for conservation.

On the legislative front, the bill to enable the ISO to expand its day-ahead market to utilities outside California will be taken up next year as part of the two-year legislative session. As noted in this issue’s article, we continue to support lawmakers with technical advice and analysis as they consider this effort to build a more resilient, greener and affordable electricity network.

Last, the ISO welcomed Portland General Electric as the fifth entrant to our western Energy Imbalance Market (EIM) on Oct. 1. Participation in the western EIM – and the cost savings to participants – continue to grow. We recently published our Q2 2017 EIM benefits study, which indicates that benefits to California and western states now total $213 million since EIM began in 2014.


Steve Berberich, President and CEO

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North American solar eclipse recap


Americans were captivated on Monday, August 21 with the first North American total solar eclipse since 1979. A large gathering of media and visitors at the ISO headquarters in Folsom, California watched as the eclipse began shortly after 9 a.m. Pacific Time, when the ISO grid saw about 6,400 megawatts (MW) of online solar generation begin to fall. Northern California experienced a 76-percent eclipse while the southernmost part of the state experienced a 58-percent eclipse. By noon PT, the eclipse was over. Grid operators were successful in replacing lost solar generation with other resources without compromising reliability.


       Graph showing eclipse impact on solar production (yellow line) starting about 9 a.m. PT.
       Thermal or natural gas (brown), hydro electric (light blue) and wind (dark blue).

Although the eclipse looked relatively uneventful, the hard work planning for the eclipse began more than a year in advance. Forecasting, planning, and continuous discussion with market participants proved essential for successfully managing the grid during the eclipse, in which solar generation ramped off the system at rate of 48 MW per minute, and roared back as up to 150 MW per minute, which is much faster than the normal ramp rate of about 13 MW per minute.

As part of its operational readiness plan, the ISO lined up additional generation and regulation energy, and ordered resource owners to postpone any maintenance work until after the event.

When the eclipse reached its peak at about 10:25 a.m. PT, the ISO had lost about 3,547 MW of solar output, plus demand increased 1,468 MW from the loss of rooftop solar, which was load that shifted to the ISO for support. One MW typically powers 750 to 1,000 homes.

The ISO used hydropower and natural gas resources along with imported energy from the ISO’s real-time western Energy Imbalance Market to make up for the lost solar production. To further manage any risks, the ISO coordinated closely with natural gas companies, utilities, and generators.

The eclipse was a spectacular event to view, and for grid operators in California and across the U.S., to test their knowledge and skills. For more on this event, click here to visit the ISO’s Solar Eclipse webpage.

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EIM savings grow with new participants


The western Energy Imbalance Market (EIM) has saved $213 million for utilities and their customers as of the second quarter 2017. This real-time wholesale energy market enables participants to buy and sell low-cost power in eight western states and has proven again that sharing resources across a wide geographic region helps keep costs down for more than 38 million consumers while enhancing grid reliability.

During Q2 2017, the EIM reduced carbon emissions by 28,700 metric tons by using clean renewable resources that otherwise would have been turned off because of low demand. The carbon reduction is equivalent to eliminating the emissions of 6,062 passenger vehicles driven for one year. So far, the EIM has reduced emissions since its inception in 2014 by 204,941 metric tons.

The ISO and five out-of-state utilities participate in the western EIM: PacifiCorp, NV Energy, Puget Sound Energy and Arizona Public Service. The fifth entrant, Portland General Electric, entered the market on October 1. Idaho Power and Canada’s Powerex are scheduled to join in April 2018, followed by the Balancing Authority of Northern California/Sacramento Municipal Utility District, Seattle City Light, and Los Angeles Department of Water and Power in April 2019. In April 2020, Salt River Project of Phoenix is slated to enter the market.

The EIM’s state-of-art technology automatically optimizes the real-time grid to find low-cost energy regardless of its location to serve consumers in California, Arizona, Oregon, Washington, Utah, Idaho, Wyoming and Nevada. Click here to learn more about the western EIM and see the latest benefits report.

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Record heat challenges ISO grid


It has been a long, hot summer.

The California grid was challenged with record-setting heat this summer, pushing demand to levels the state has not seen in more than a decade.

The ISO called a Flex Alert four times during the summer, asking consumers to voluntarily conserve energy to help grid operators avoid more serious grid impacts or emergencies. Conservation by consumers was successful in helping to stabilize the grid.

The summer season started early with a heat wave in mid-June that prompted the ISO to issue two back-to-back Flex Alerts on June 20 and 21. A third Flex Alert was issued on August 29.

On September 1, a fourth Flex Alert was issued in response to the highest electricity demand since 2006. The forecasts predicted that California would exceed the all-time peak record demand of 50,270 MW set on July 24, 2006. The peak demand ultimately reached 50,116 MW, just 154 MW short of the 11-year-old record.

The ISO reserves the request for conservation only when absolutely needed, and always appreciates the help consumers in California provide during Flex Alerts. Efforts by residents and businesses eased spikes in demand, and helped the ISO avoid from moving to more serious options such as rotating outages. The ISO sincerely thanks consumers for their efforts.

To keep up with grid conditions and alerts, download the ISO’s mobile app, ISO Today, or on the web by clicking here. You can also sign up for Flex Alert notifications at


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Battery storage needed for future grid


The ISO is an active supporter of energy storage on the high-voltage grid. Much progress has been made in determining how to connect and dispatch these devices. At this time, there are about 5,000 megawatts (MW) of energy storage projects in the network study queue, well above the state mandate to add 1,325 MW of storage by 2020.

California’s investor-owned and municipal utilities are adding storage to their resource mix. For example, Southern California Edison (SCE) is 180 MW shy of procuring its 580-MW storage target.

SCE worked with the ISO in 2016 to fast-track interconnecting storage to help lower the risks of potential gas shortages from the limitations placed on using the Aliso Canyon natural gas storage facility in Southern California. Taking a unique approach, SCE paired the four battery storage systems with substations and power plants.

Pacific Gas & Electric was the first utility to successfully use a small battery storage system to participate in the ISO market in late 2016. The utility also has a 2020 procurement target of 580 MW and interconnected its first lithium-ion system featuring 396 Tesla power packs in February 2017.

The ISO currently has 119 MW of battery energy storage connected to the grid, and is conducting a stakeholder initiative, the “Energy Storage and Distributed Energy Resources”, to identify the actions needed that will enhance the ability for storage resources to participate in the ISO market.

Battery storage, along with electric vehicles, rooftop solar, and demand response, are a growing — and important — part of the future grid, as the system strives to meet state clean energy goals and strengthen grid reliability. Click here to learn more about energy storage solutions.

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ISO to live stream Symposium


The ISO will live stream its annual Stakeholder Symposium next week via its website. The event will bring together nearly 1,000 executives and industry leaders to share ideas, visions, challenges, and solutions for the greener, more efficient electric system of the future.

Click here to learn more about the 2017 Symposium. Click here to visit the live streaming webpage during the event, and watch videos from last year’s Symposium.

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