What is battery storage?

Battery storage, or battery energy storage systems (BESS), are devices that enable energy from renewables, like solar and wind, to be stored and then released when the power is needed most.

Lithium-ion batteries, which are used in mobile phones and electric cars, are currently the dominant storage technology for large scale plants to help electricity grids ensure a reliable supply of renewable energy. We’ve begun deploying this technology with heavier equipment, working with Viridi Parente – a company that makes battery storage systems for industrial, commercial and residential buildings.
 

Why is battery storage important and what are its benefits?

Battery storage technology has a key part to play in ensuring homes and businesses can be powered by green energy, even when the sun isn’t shining or the wind has stopped blowing.

For example, the UK has the largest installed capacity of offshore wind in the world, but the ability to capture this energy and purposefully deploy it can increase the value of this clean energy; by increasing production and potentially reducing costs.

Every day engineers at National Grid and electricity grids worldwide must match supply with demand. Managing these peaks and troughs becomes more challenging when the target is to achieve net zero carbon production. Fossil-fuel fired plants have traditionally been used to manage these peaks and troughs, but battery energy storage facilities can replace a portion of these so-called peaking power generators over time.

The UK government estimates technologies like battery storage systems – supporting the integration of more low-carbon power, heat and transport technologies – could save the UK energy system up to £40 billion ($48 billion) by 2050, ultimately reducing people’s energy bills.

Prescott Hartshorne, a Director at National Grid Ventures in the US, says: “Storage enables further renewable generation, both from an operational and reliability perspective. It’s also a key piece of our utility customers’ ongoing evolution and transition to renewables.”

 

How exactly does a battery storage system work?

Battery energy storage systems are considerably more advanced than the batteries you keep in your kitchen drawer or insert in your children’s toys. A battery storage system can be charged by electricity generated from renewable energy, like wind and solar power.

Intelligent battery software uses algorithms to coordinate energy production and computerised control systems are used to decide when to store energy or to release it to the grid. Energy is released from the battery storage system during times of peak demand, keeping costs down and electricity flowing.

This article is concerned with large-scale battery storage systems, but domestic energy storage systems work on the same principles.
 

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What renewable energy storage systems are being developed?

Storage of renewable energy requires low-cost technologies that have long lives – charging and discharging thousands of times – are safe and can store enough energy cost effectively to match demand.

Lithium-ion batteries were developed by a British scientist in the 1970s and were first used commercially by Sony in 1991, for the company’s handheld video recorder. While they’re currently the most economically viable energy storage solution, there are a number of other technologies for battery storage currently being developed. These include:

• Compressed air energy storage: With these systems, generally located in large chambers, surplus power is used to compress air and then store it. When energy is needed, the compressed air is released and passes through an air turbine to generate electricity.

• Mechanical gravity energy storage: One example of this type of system is when energy is used to lift concrete blocks up a tower. When the energy is needed, the concrete blocks are lowered back down, generating electricity using the pull of gravity.

• Flow batteries: In these batteries, which are essentially rechargeable fuel cells, chemical energy is provided by two chemical components dissolved in liquids contained within the system and separated by a membrane.

Prescott Hartshorne says: “The next decade will be big for energy storage in general and for batteries in particular. It will be an important proving time for batteries and for other technologies.”
 

Last updated: 9 May 2023
The information in this article is intended as a factual explainer and does not necessarily reflect National Grid's strategic direction or current business activities.

Imagine you’re home on a stormy night, watching TV with the washing machine running, and all of a sudden the power goes out. Now imagine the same scenario, except you have a rooftop solar energy system with battery storage. When the power goes out in your neighborhood, you’d be blissfully unaware.  

A common myth about solar power is that you can count on it only when the sun is shining. You do need sunshine to generate electricity with solar, but what about the times when the sun isn’t shining? Most people rely on electricity from the power grid to supplement their solar-generated power. But residential solar energy systems paired with battery storage—generally called solar-plus-storage systems—provide power regardless of the weather or the time of day without having to rely on backup power from the grid. Here are the benefits of a solar-plus-storage system:

• Around-the-clock power. If you use the utility billing mechanism known as time-of-use, and don’t have a solar energy system, your electricity in the evening is likely more expensive because of the higher demand on the system. With battery storage, however, you can use electricity generated during the day later on, rather than relying on the utility for power. This is also useful if you live in an area with frequent power outages.
• Pocketbook protection. If your utility raises electricity rates, you can avoid that with a battery. Battery storage lets you leverage low-cost energy that has already been generated and stored, ensuring your rates stay low and don’t affect your monthly budget. In some cases, you can even sell the energy you’re storing back to the grid when the rates are higher and bank the profit.
• Better monitoring. A solar-plus-storage system can help you to better track the energy your system is generating through monitoring capabilities, providing an enhanced level of transparency and precision. These systems allow you to track the energy your home is producing and using in real time.
• More energy self-sufficiency. While most jurisdictions require homes to be connected to their local utility even if they don't use any electricity from the utility, a solar-plus-storage system takes you closer to “off the grid” status. Battery storage means you don’t have to rely on your utility to deliver electricity to your home most days of the year. And you can always keep some battery capacity in reserve, so that if the power goes out in your neighborhood, your house will be the one with the lights on.

You may be sold on the merits but curious about the costs. A solar-plus-storage system costs about $25,000–$35,000, depending on the size of the battery and other factors. It is easier and cheaper to install the panels and battery at the same time. But if you’ve already installed solar panels and want to add storage, you can: The battery will cost anywhere from $12,000 to $22,000. Ask your solar installer if they can add a battery to your system. If you purchase a battery on its own or a solar-plus-storage system, you will be eligible for federal tax credits. Some states provide additional solar battery incentives. 

To learn more about resources available to consumers, including guidance on demystifying the solar installation process, check out the Homeowner’s Guide to Going Solar.