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A Leader in Energy Storage

At the end of 2020, Southern California Edison had installed and procured battery storage capacity of approximately 2,050 megawatts.

SCE Battery Energy Storage Resources

Battery storage is a flexible resource. One of the many ways it can be used is to capture and store energy during times of low demand, when it is plentiful and inexpensive, and using it during times of high demand, when energy is in short supply and more expensive.

As more and more renewable resources such as solar and wind come online, batteries can help smooth out the fluctuations in these resources by storing the energy they generate and supplying it to the grid later when the sun isn’t shining or the wind isn’t blowing. Energy storage can also support local distribution circuits impacted by the high penetration of renewable resources and improve power quality.

Batteries can also be used to respond to the California Independent System Operator’s signals during high-demand events, heat waves or when the energy grid is strained.

Here are some of the ways we are using this flexible resource:

Incorporating Solar

The Connolly Energy Storage System is located on the Pronghorn Circuit near 15 solar farms.

Connolly Energy Storage

The 2.8MW/5.6MWh Connolly battery energy storage system is connected to a circuit that supports 15 small solar farms and rooftop solar installations. When customers aren’t using much electricity, excess power can overload the circuit. SCE will use the battery energy storage system to manage this reverse flow.

Read more at ENERGIZED by Edison

Enhancing Reliability


SCE’s first battery energy storage system pilot that supports a local distribution circuit, Distribution Energy Storage Integration, will help with local reliability. One way it supports local reliability is during the hottest months when there is an increased demand for electricity, driven by large industrial and commercial customers or the use of residential air conditioners. Located in Orange, DESI I can supply 2.4 megawatts of power continuously for about an hour and a half.

Hybrid Enhanced Gas Turbine System

The Hybrid Enhanced Gas Turbine system, or Hybrid EGT, is a 10-megawatt battery storage system, combined with the gas turbine. SCE has installed systems at each of two gas-fired peaker sites — Center substation in Norwalk and Grapeland substation in Rancho Cucamonga. The systems allow the peaker plants to respond quicker to changing energy needs and increase the reliability of the electrical grid while reducing fuel use and air emissions. They are available 24/7 and can instantly step in when the wind or sun can no longer meet system needs.


Mira Loma Energy Storage System

Located in Mira Loma, The Tesla Energy battery facility contains two 10-megawatt systems, each containing 198 Tesla Powerpacks and 24 inverters. That is enough to store 80 megawatt-hours of electricity, enough energy to power more than 2,500 households for a full day. The modular system allows it to be connected to two separate circuits at the Mira Loma substation. It increases SCE’s grid reliability by providing battery storage of electricity during off-peak hours and using the stored energy to meet demand during peak.

Vehicle to Grid

Vehicle-to-grid, or V2G, is two-way technology that allows EV batteries both to charge and discharge power onto the grid while they are plugged in, the same way stationary batteries do. V2G has the potential to make EV owners energy producers. In 2020, SCE launched a demonstration project that will attempt to validate whether V2G could actually result in a reduction of customers’ electric bills in exchange for energy they supply from their EV batteries when they are connected to the grid. It will also examine standardization of equipment that would be necessary to make those connections possible.

Virtual Power Plants

Virtual power plants are networks of customer-sited batteries that can be called on to supply energy to the grid. To help enhance the region’s electric system reliability needs, SCE has entered into several demand response contracts with residential energy storage companies to provide energy from customers’ batteries when the grid needs it most.

SCE is also conducting a pilot with Sunrun to determine how virtual power plants respond to different types of high-energy demands and if they deliver power as expected. While some high-energy demands are predictable, like those that take place almost every day at the same time, others are less so including unexpected weather conditions or emergencies.

Developing Resiliency

Solar panels located at San Jacinto High School help power microgrid.

San Jacinto Microgrid

Microgrids have a traditional grid connection and can function either connected or islanded (separated) from the grid. When they are islanded, they can operate autonomously to support specific load needs in unique situations.

To support resiliency in our communities, SCE has launched a Microgrid Resiliency Pilot. The first project is with San Jacinto High School and will power its gymnasium and restroom facilities from solar and battery storage in the event of a power outage caused by weather, fire or other emergencies. The project includes a microgrid controller, which manages the interaction between the Tesla battery and the solar system and allows the system to enter microgrid mode. The system also uses a manual transfer switch to safely transfer the facility load from the grid to the microgrid.

Read more at ENERGIZED by Edison

Improving Circuit Voltage Control



DESI 2 sits in a compact, urban SCE right of way at the end of a circuit in Santa Ana. SCE is using the 1.4MW/3.7MWh system to improve circuit voltage control, which affects power quality. Energy stored in this battery might also be used in the wholesale energy market to support providing clean, carbon-free energy for SCE customers.

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