EEI > Issues & Policy
Energy Storage
Key Facts
Invest in ~70%
Of Battery Storage Technology
According to the most recent data, electric companies represent roughly 70 percent of total investment in battery storage technology. Electric companies own, procure, or utilize 98 percent of all mostly grid-connected energy storage today, of which roughly 92 percent is pumped hydropower storage​​.
400% Increase in Installations
From 2014
Investment in advanced energy storage is growing rapidly, with an estimated 280 megawatts installed in 2017 alone, up 400 percent from 2014.
Active in 42%
Of Microgrid Projects
Electric companies are active partners in microgrid deployment and are involved in 42 percent of the projects, a virtual quadrupling since 2014.​
What Are the Benefits of Energy Storage?

​Energy storage improves reliability and resiliency for the energy grid and electricity customers.

For Homes
For Businesses
For Electric Companies
Trends & Key Issues
  • ​Battery storage is the fastest-growing energy storage technology today, increasing eight-fold from 2013 to the first half of 2020.
  • Over the last seven years, electric companies were responsible for 70 percent of total energy storage capacity deployed. 
  • Battery energy storage is increasingly cost effective for businesses, households, and electric companies, which are rapidly adopting batteries and using them alone or in combination with other energy resources.
  • As the owners and operators of the energy grid, electric companies are essential to harnessing the benefits of energy storage and microgrids for customers, and can help maximize and optimize the services these technologies can provide.
  • Microgrids provide numerous benefits to the customers they serve, but can also provide important public benefits when deployed optimally, like protection of critical infrastructure and advanced learning of smart grid technologies.

Energy Storage Trends & Key Issues - October 2020​​​

Company Highlights
  • ​Oncor: Solar, Battery, Microturbine Microgrid
    The autonomous microgrid at Oncor’s System Operating Services Facility consists of four interconnected microgrids and nine different distributed generation resources: two solar PV arrays, a microturbine, two energy storage units, and four generators. The microgrid project aims to test Oncor’s ability to operate a microgrid, as well as to showcase how solar, microturbines, and battery storage can integrate renewable energy sources into the energy grid through advanced hardware and software. The two batteries enable integration of solar power, allow for voltage control, and release stored energy during an outage. The project is operational since 2015. Learn More. 
  • Ameren: Cybersecurity Microgrid, Champaign
    This microgrid, operational since 2016, is the only known large-scale microgrid in the nation capable of seamlessly transitioning the power source for an entire distribution circuit from the microgrid to the grid and vice versa. It also marks the first installation by a U.S. energy company of a military-grade cybersecure microgrid controller. The project exemplifies the first time an electric company is serving paying customer loads on an electric company distribution feeder. The energy generated by the microgrid can be delivered directly to local customers, routed to the central grid, or stored in the microgrid’s battery. The microgrid has an energy storage battery as well as a complex distributed energy resource mix that also integrates wind, solar, and natural gas.​ Learn More.​
  • Alabama Power Smart Neighborhood Microgrid

    ​Alabama Power partnered with a property developer to build 62 high-efficiency homes (35 percent more efficient than comparable newly built homes) that all are connected to a microgrid capable of islanding by Alabama Power. The neighborhood microgrid includes a 330 kW solar array, a 300 kW/680 kWh battery storage system, and a 400 kW natural gas generator for reserve power. The high-performance homes score a 45 on the HERS Index and feature 2x6 construction, triple-pane windows, a 20 SEER heat pump, a heat pump water heater, and in-home smart technology like controllable lighting and outlets. All 62 homes sold within six months. Learn More.​

  • Xcel Energy Pena Station Solar + Storage Microgrid

    ​Xcel Energy partnered with Panasonic and Denver’s International Airport (DEN) to build a 1 MW/2 MWh battery energy storage system adjacent to Panasonic’s facility. Also part of the project, a 1.6 MW Carport Solar PV array is located at a nearby DEN light rail stop. During normal operations, the system is connected to the company’s distribution feeder and enables renewable integration and other grid support. During an outage, the battery, combined with Panasonic’s 259 kW rooftop PV system, power Panasonic’s facility​. Learn More.​

  • Arizona Public Service (APS) – Punkin Center Energy Storage Project

    APS installed two, 1 MW/4 MWh Advancion (AES/Fluence) battery energy storage systems in Punkin Center, a small town 90 miles NE of Phoenix, as a cost-effective alternative to upgrading about 20 miles of 21 kV cable. During the 20 to 30 peak demand days each year, APS can deploy battery storage capacity to meet the area’s energy needs. Learn More.

  • San Diego Gas & Electric, Escondido Substation Storage
    ​The Escondido Substation Storage in California is the largest lithium-ion battery storage project in North America. Owned by San Diego Gas & Electric (SDG&E) and built in partnership with Fluence, the 30 MW storage facility is comprised of approximately 400,000 batteries installed in 20,000 modules within 24 containers. At capacity, it can provide electricity to 20,000 homes for four hours. The facility has two primary purposes. First, it helps balance the large amount of solar generation entering the Southern California energy grid during peak daylight hours. Second, the facility enables energy time shift, which allows SDG&E to make smart financial decisions about when to supply and to store energy; these decisions directly benefit customers. Learn More.
Additional Resources
August 31, 2020
EEI Response to Request for Information Regarding Energy Storage Grand Challenge
Electric Perspectives, January/February 2018
Customer-Sited Energy Storage: A Win-Win for Energy Customers and the Energy Grid
Electric Perspectives, November/December 2017
AES Harnesses Battery Power to Help California Meet Energy Goals
March 2021
SDG&E’s Battery Project Continues to Advance Clean Energy Microgrids
May 2020
SCE Will Add Energy Storage Projects
April 2019
Electric Companies Help Maximize the Benefits of Energy Storage
February 2019
Harnessing the Potential of Energy Storage
October 2018
Leading the Way: U.S. Electric Company Investment and Innovation in Energy Storage