A battery energy storage system (BESS), also called a battery storage power station or battery grid storage, is a type of technology that uses groups of batteries to store electrical energy in the power grid. Battery storage is the fastest type of power source that can be used quickly on electric grids. It helps keep grids stable because it can switch from being ready to provide power to fully active in less than a second to handle unexpected problems on the grid.
Battery energy storage systems are usually built to provide their full power for 1 to 4 hours. Newer technologies are being developed to extend this time to meet changing needs. Battery storage is used for short-term power needs during peak times and for services that help keep the grid running smoothly, such as providing backup power and controlling the grid’s frequency to reduce the risk of power outages.
These systems are often placed near active or old power stations to save costs by sharing the same connection to the grid. Since battery storage does not need fuel, is smaller than power plants, and does not have chimneys or large cooling systems, they can be built quickly and placed in cities, close to where electricity is used, or even inside buildings.
As of 2021, the largest battery storage systems are much smaller than the largest pumped-storage power plants, which are the most common type of grid energy storage. For example, the Bath County Pumped Storage Station, the second-largest in the world, can store 24 GWh of electricity and provide 3 GW of power. In contrast, the first phase of Vistra Energy’s Moss Landing Energy Storage Facility can store 1.2 GWh and provide 300 MW. However, battery storage does not need to be large—many small systems can be spread across a grid to increase reliability and total storage. By 2025, the global power capacity of battery storage was 267 GW, with an energy capacity of 610 GWh.
As of 2019, battery storage was usually cheaper than open cycle gas turbine power for use up to two hours. Around 365 GWh of battery storage was installed worldwide, and this number is growing quickly. The average cost to store energy (LCOS) has decreased rapidly. From 2014 to 2024, the cost of storage dropped in half every 4.1 years. In 2020, the cost was US$150 per MWh, and by 2023, it had dropped to US$117 per MWh.
Construction
Battery storage power plants and uninterruptible power supplies (UPS) are similar in how they work. However, battery storage power plants are much larger in size.
For safety, the actual batteries are kept in separate buildings, such as warehouses or containers. Like a UPS, one challenge is that the energy stored in batteries is in the form of direct current (DC), while most power networks use alternating current (AC). Because of this, extra devices called inverters are needed to connect battery storage power plants to the high-voltage power grid. These systems use components like gate turn-off thyristors, which are often found in high-voltage direct current (HVDC) transmission.
Different battery systems may be used based on the power-to-energy ratio, expected lifespan, and cost. In the 1980s, lead-acid batteries were the first type used in battery-storage power plants. Over the next few decades, nickel–cadmium and sodium–sulfur batteries became more common. Starting in 2010, lithium-ion batteries are increasingly used because their costs dropped quickly due to the electric car industry. Today, lithium-ion batteries are the main type used. A 4-hour vanadium redox battery with a capacity of 175 MW / 700 MWh opened in 2024. Lead-acid batteries are still used in low-cost applications.
Safety
Battery Energy Storage Systems (BESS) are made up of sealed battery packs that are monitored electronically and replaced when their performance drops below a certain level. Batteries lose effectiveness over time due to repeated charging and discharging. This wear and tear happens more quickly at high charging speeds and when the battery is used heavily. This aging can cause reduced performance, overheating, and in severe cases, leaks, fires, or explosions. Sometimes, battery storage stations use flywheel systems to protect battery power. Flywheels can handle sudden changes in energy demand better than older battery systems.
BESS warranties often include limits on how much energy the batteries can store and release over their lifetime, measured in the number of charge-discharge cycles.
Lead-acid batteries, an older technology, are used in some BESS systems. An example is a 1.6 MW peak, 1.0 MW continuous battery installed in 1997. Compared to newer batteries, lead-acid batteries store less energy for their size but can provide large bursts of power. However, non-sealed lead-acid batteries release hydrogen and oxygen gas when overcharged, which requires regular water refills and proper ventilation to avoid damage or explosions. This maintenance is costly, and newer batteries like lithium-ion do not require this.
Lithium-ion batteries last longer with little maintenance, store more energy for their size, and lose less energy when not in use. These features make them well-suited for large-scale energy storage systems.
Some lithium-ion batteries, especially those with cobalt, have fire risks. Although BESS incidents occur about 10–20 times yearly (mostly in the first 2–3 years), the failure rate has decreased. Most failures involve system controls or other components, with 11% linked to battery cells. Examples of BESS fires include incidents at 23 battery farms in South Korea (2017–2019), a Tesla Megapack in Geelong, a battery module fire in Arizona, and cooling system failures at the Moss Landing LG battery. These events have led to more research on fire safety solutions.
By 2024, lithium iron phosphate (LFP) batteries became a major option for large storage systems because their parts are widely available, they last longer, and they are safer than nickel-based lithium-ion batteries. An LFP system installed at Paiyun Lodge on Mt. Jade in Taiwan has operated safely since 2016.
Sodium-based batteries are also being explored for BESS. Compared to lithium-ion batteries, sodium-ion batteries are less expensive, safer, and have similar power delivery, though they store less energy for their size. They function similarly to lithium-ion batteries but use sodium instead of lithium as the main ion. Some sodium batteries, like sodium-sulfur batteries, can operate safely at high temperatures. Companies like Altris AB, SgNaPlus, and Tiamat claim high safety for their sodium batteries. Sodium-based batteries are not yet fully commercialized, but the largest BESS using sodium-ion technology began operating in 2024 in Hubei province, with a capacity of 50 MW / 100 MWh.
Operating characteristics
Battery storage power plants do not have moving parts, so they can start and control operations very quickly, as fast as 10 milliseconds. This ability helps reduce sudden changes in electrical power networks when they operate near their maximum capacity or experience problems. These changes, which can last up to 30 seconds, may cause large power fluctuations that could lead to power outages in certain areas. Factors like voltage, frequency, and phase are involved in these changes. A well-sized battery storage plant can effectively manage these fluctuations, making it useful in areas where power systems run at full capacity, which increases the risk of instability. However, some batteries lack strong control systems and may fail during smaller disruptions they should handle. Batteries are also used to reduce high power demand for short periods, up to several hours. A newer use is helping power lines carry more electricity safely by balancing local differences between power supply and usage.
Battery storage plants can also be paired with renewable energy sources in systems that operate independently.
Market development and deployment
By 2025, the world had 267 gigawatts of battery power and 610 gigawatt-hours of energy storage. This compared to 200 gigawatts of power and 9,000 gigawatt-hours of energy storage from pumped-storage hydroelectricity, according to the International Hydropower Association. Batteries had more power capacity than pumped-storage, but they stored much less energy. Battery prices dropped quickly, and the average cost worldwide was about $120 per kilowatt-hour in 2025.
Between 2010 and 2025, battery and photovoltaic (solar) prices decreased similarly due to improvements in technology. Battery cells, which cost 30-40% of a full system, were the main expense. By 2026, batteries became a type of investment that could be managed by groups, allowing small companies to partner with investors who did not know much about electricity. This was different from the usual method of one company owning and running an energy facility.
By mid-2025, China had over 100 gigawatts of battery storage (164 gigawatts total). At the end of 2024, China had 62 gigawatts of power and 141 gigawatt-hours of energy storage. In 2020, China added 1,557 megawatts of battery storage, with 27% of that capacity supporting solar projects. By May 2025, China had 106.9 gigawatts of battery storage power and 240.3 gigawatt-hours of energy. Worldwide, 9 gigawatt-hours of battery storage were added in April 2025.
In 2025, the United States installed 57.6 gigawatt-hours of battery storage. In 2024, the U.S. had 12.3 gigawatts of power and 37.1 gigawatt-hours of energy storage. The U.S. had 70 gigawatt-hours of battery production capacity in 2025, matching the size of the domestic market. In 2022, U.S. battery storage capacity doubled to 9 gigawatts of power and 25 gigawatt-hours of energy. By the end of 2021, battery storage reached 4,588 megawatts. In 2021, the cost of a 60-megawatt/240-megawatt-hour battery installation in the U.S. was $379 per usable kilowatt-hour, a 13% drop from 2020. In 2010, the U.S. had 59 megawatts of battery storage from 7 plants. By 2015, this grew to 351 megawatts from 49 plants. In 2018, capacity reached 869 megawatts from 125 plants, storing up to 1,236 megawatt-hours of energy. By 2020, U.S. battery storage reached 1,756 megawatts. In 2015, the U.S. storage market grew by 243% compared to 2014.
In June 2024, the United Kingdom had 4.6 gigawatts of power and 5.9 gigawatt-hours of energy storage. In 2022, the UK’s capacity grew by 800 megawatt-hours, ending at 2.4 gigawatts of power and 2.6 gigawatt-hours of energy. By May 2021, 1.3 gigawatts of battery storage was operating, with 16 gigawatts of projects planned for future development.
By the end of 2024, Europe had 61 gigawatt-hours of battery storage, adding 21 gigawatt-hours that year. Germany and Italy each contributed about 6 gigawatt-hours to this growth. Installation costs in Europe ranged between €300 and €400 per kilowatt-hour in 2024. In 2022, Europe added 1.9 gigawatts of new battery capacity. In Germany, 15 gigawatts of battery storage and 22 gigawatt-hours of energy were reported in September 2025, mostly from over 2 million home-based systems. Germany also had 1.84 million registered battery electric vehicles, estimated to store over 115 gigawatt-hours of energy.
Japan’s renewable energy capacity grew by over 30% in five years, increasing demand for battery storage. More than half of the 2.4 gigawatts of battery storage awarded in recent auctions went to foreign companies. In 2024 alone, projects approved included 1.37 gigawatts of power and 6.7 gigawatt-hours of energy. Japan’s government supports battery storage by guaranteeing fixed costs for 20 years. However, limited price changes and a minimum price in Japan’s power market may reduce returns for storage operators, showing a need for better rules.
In 2024, CRRC had 8% of the global battery storage market, Sungrow had 14%, and Tesla Energy had 15%. Some companies use retired electric vehicle batteries to build storage systems, which may cost 50% less than new batteries. However, buyers may only pay about 10% of the original cost for these used systems. In 2024, a 53-megawatt-hour battery storage facility built from 900 used electric vehicle batteries was completed in Texas.
After a major blackout in the Iberian Peninsula in April 2025, which cut off the region’s power grid from the rest of Europe for five seconds and caused economic losses of up to €4.5 billion, Spain focused more on system resilience. Battery storage in Spain was less than 20 megawatts before the blackout but is now a key part