SDG&E Prepared for the "Great American Eclipse"

Company secures enough energy to power San Diego when solar generation expected to significantly drop

SAN DIEGO, Aug. 17, 2017 – On August 21, during the mid-morning hours in San Diego, the moon will pass in front of the sun casting a shadow on the Earth’s surface. As the sky darkens, the sun is expected to be obscured by nearly 60 percent here locally, resulting in a loss of 500 megawatts (MW) of solar generation--that’s about 14 percent of the electricity customers consume on a typical warm summer day.

In preparation for the ‘Great American Eclipse,’ power grid operators at San Diego Gas & Electric (SDG&E) have spent months planning and preparing to ensure that enough energy is flowing through the electric grid to safely and reliably meet customer demand.

“Managing and operating a power grid is a 24/7 job and while we plan ahead, there are often quick decisions that need to be made to maintain a balance between the exact amount of electricity at the exact time to consistently meet the energy needs of the region,” said Caroline Winn, chief operating officer for SDG&E. “Predicting how the obstructed sun will interfere with solar production has added another level of complexity, but we want to reassure our customers that we have secured enough resources to meet their energy needs--even with significantly less solar generation on hand.”

Solar energy, which is intermittent by nature, varies throughout the day and is directly affected by the weather. On any given day, power grid operators are challenged with making real-time adjustments to electric forecasts to account for any fluctuations on the grid, like a solar eclipse.

Further complicating the issue during the eclipse is the fact that in San Diego, more than 114,000 private rooftop solar installations are scattered throughout local communities. That’s about 7 percent of SDG&E’s customers, who together are capable of producing up to 760 MWs of solar energy--which is greater than any single power plant connected to the SDG&E power grid.

In order to meet customers’ needs during the eclipse, SDG&E will rely on natural gas facilities and energy storage, which are both currently playing an essential daily role in maintaining a reliable power grid. With both resources online, SDG&E can ensure the delivery of clean, safe and reliable power to customers during this unique event.

While there is no call for conservation at this time, SDG&E is reminding customers that making small changes to save energy would be helpful. On August 21, SDG&E will be in close coordination with the California Independent System Operator (CAISO) to ensure the stable and reliable flow of power throughout the state. All facilities and resources will be on standby should we experience above average temperatures.

Below are some easy tips for customers who want to help conserve energy during the solar eclipse:

  • Adjust your thermostat to 78F for AC.
  • Avoid charging your electric vehicle during peak demand hours.
  • Do loads of laundry during off-peak hours.
  • Run your dishwasher earlier in the day, or late at night.

SDG&E is an innovative San Diego-based energy company that provides clean, safe, and reliable energy to better the lives of the people it serves in San Diego and southern Orange counties. More than 4,200 employees work to provide the cleanest, safest and most reliable energy in the West. With 43 percent of the power mix coming from renewable resources such as solar and wind, SDG&E has far exceeded California’s goal of delivering 33 percent, has fueled the adoption of electric vehicles and energy efficiency through unique customer programs, and supports a number of non-profit partners. SDG&E is a subsidiary of Sempra Energy (NYSE: SRE), a Fortune 500 energy services holding company based in San Diego. For more information, visit or connect with SDG&E on Twitter (@SDGE), Instagram (@SDGE) and Facebook.