Solar Battery Storage

How it Works & the Options Available (UK)

This introductory guide explores the mechanics of solar battery storage in the UK. It has been written with a broad, non-technical audience in mind.

We cover residential, commercial, and industrial aspects to help people understand the wide range of solar battery storage options available. To learn more about how Wattstor helps our commercial and industrial customers, read about the problems we solve.

What is solar battery storage?

Solar battery storage, often referred to as a Battery Energy Storage System (BESS), is a technology that allows you to store excess solar energy produced by your solar panels for later use. Instead of sending the surplus energy back to the grid, this energy is stored in batterie. It can then be drawn upon when the sun isn’t shining, such as during the evening or on cloudy days. This enhances the self-sufficiency of a solar power system, ensuring that you can use solar energy even when the sun isn’t directly powering your panels.

According to the Solar Power Porta, in 2022 the operational capacity of energy storage sites in the UK increased by almost 800MWh, the largest annual deployment figure in history. Battery developments are not only set to grow in number but also in scale, thanks to the government’s decision to lift size restrictions on project planning. As a result, the most common size of BESS projects in the UK is set to leap, with some single projects even topping 1 GW.

Popular BESS brands that have made a mark in the industry include the national energy providers like EDF and utility-scale providers like Anesco. These solar storage companies, among others, offer a range of storage capacities and technologies. They cater to the diverse needs of commercial properties looking to optimise their solar energy usage.

The latest technology for solar battery storage

The latest and most popular technology used for solar battery storage is lithium-ion batteries. Lithium-ion batteries have a high energy density, meaning they can store a considerable amount of energy in a relatively small and lightweight cell. They also have a long lifespan and can be cycled many times (charged and discharged) before they need to be replaced.

Different battery storage technologies can be used for grid applications, such as:

  • Lithium-ion (Li-ion)
  • Sodium sulphur
  • Lead acid batteries can be used for grid applications.

However, in recent years, most of the market growth has been seen in Li-ion batteries.

Solid-state battery cells with lithium-metal anodes have the potential to improve today’s current battery technology significantly too. They offer increased energy density, faster charging, enhanced safety, longer lifespan and, importantly, could result in lower battery pack cost upon gaining maturity.

Sodium-ion technology is early in its development phase and faces challenges in energy density, cycle life, and performance. Despite these hurdles, ongoing research continues to explore sodium-ion potential for Battery Energy Storage Systems (BESS).

How commercial solar battery storage works

Commercial solar battery storage works by storing excess solar energy generated during the day so that it can be used later, at night or during cloudy days. This can help businesses to reduce their reliance on the grid, save money on their energy bills, and improve their overall energy resilience.

Commercial solar battery storage systems are typically made up of a large number of individual batteries that are connected together. The batteries are charged using solar panels, and they can be discharged to power a business’s electrical load when needed.

There are two main ways that commercial systems work best for UK businesses and they include the following:

(1) Peak shaving

A way of reducing electricity costs by avoiding peak demand charges. Peak demand charges are based on a business’s highest energy usage during a certain period of time, such as a month or a year. By using stored solar energy during peak demand periods, businesses can reduce their peak demand charges and save money on their energy bills.

(2) Load shifting

A way of reducing electricity costs by moving energy usage to off-peak hours. Off-peak hours are typically at night or during the day when electricity rates are lower. By using stored solar energy during off-peak hours, businesses can reduce their overall energy costs.

The solar battery storage process

  • Solar panels on a business / site’s roof generate electricity during the day.
  • Electricity from the solar panels is used to power the business’s electrical load.
  • Any excess electricity from the solar panels is stored in the battery system.
  • At night / cloudy days, the battery system powers the business’s electrical load.
  • Battery system can also power the business’s electrical load during a power outage.

The 4 main benefits of solar battery storage

Commercial solar battery storage systems are becoming increasingly popular as the cost of solar energy continues to decline and the benefits of battery storage become more widely understood.

  1. Reduce your energy costs and increase revenue

    One of the biggest benefits of solar battery storage is that it can help you to reduce your energy costs and save money – but only with an optimised Energy Management System (EMS). By storing excess solar energy that you generate during the day, you can use it to power your home or business at night or during cloudy days, when electricity rates are typically higher. For example, a homeowner in Hertfordshire could save an average of £2,000 per year on their energy bills by installing a solar battery storage system. And a business in Greater London could save an average of £10,000 per year on their energy bills by installing a solar battery storage system.

  2. Improve your energy resilience to protect your business

    Solar battery storage can also help you to improve your energy resilience and protect your business from power outages. If the grid goes down, you can still have power to run your home or business using the stored solar energy. This is especially important for businesses that need to operate 24/7, such as data centres and hospitals. For example, a data centre in Manchester installed a solar battery storage system to ensure that it could continue to operate during power outages. The data centre experienced a power outage in 2021, but the system kept the data centre running without any interruption.

  3. Reduce your commercial carbon footprint lowering emissions

    By using solar energy to power your home or business, you can reduce your carbon footprint and help the environment. Storing solar energy is a clean and renewable source of energy that does not produce any greenhouse gas emissions.

  4. Increase your property’s commercial asset value

    Solar battery storage systems can also increase the value of your property and make your home more attractive to buyers. According to a study by the National Renewable Energy Lab, homes with solar panels sell for an average of 4.1% more than homes without solar panels. And homes with these systems sell for an average of 5.4% more than homes with solar panels alone.


Examples of how solar battery storage is being used by commercial business sites:

  • A dairy farmer in Winchester uses solar battery storage to power his milking machines and milk coolers. This has helped him to reduce his energy costs and become more energy independent.
  • A manufacturing factory in Leicester is using solar battery storage to reduce its peak demand charges. This has helped the factory to save money on its energy bills.
  • A retail store in Bristol is using solar battery storage to power its lights and refrigeration systems during power outages. This has helped the store to stay open and continue to serve its customers during power outages.
  • A schools group in Newcastle is using solar battery storage to power its schools during power outages. This has helped to ensure that students and staff can continue to learn and work during power outages.

How solar battery storage funding works

Solar battery storage funding in the UK is available to homeowners and businesses through a variety of government and private sector programs.

Government funded programs

The UK government offers a number of funding programs to support the installation of solar battery storage systems. These programs include:

  • Smart Export Guarantee (SEG): The SEG is a payment scheme that allows homeowners to earn money for exporting excess solar energy back to the grid.
  • Home Energy Scotland Loan: The Home Energy Scotland Loan is a government-backed loan that homeowners can use to finance the installation of energy efficient hardware, including solar battery storage systems.
  • Department for Energy Security & Net Zero (DESNZ)
    DESNZ provides grants and loans to businesses to help them improve their energy efficiency. This can include funding for solar battery storage systems.

Eligibility for solar battery storage funding

The eligibility criteria for funding varies depending on the program that you are applying to. However, most programs require that you own your own property and that you have a suitable roof for the installation of solar panels.

How much funding can you get for solar battery storage?

The amount of funding that you can get for solar battery storage will vary depending on the program that you are applying to and the size of your system. However, the government’s SEG scheme will pay you 3.5p per kWh for all of the solar energy that you export to the grid. And the Home Energy Scotland Loan can provide you with up to £6,000 to finance a system installation.

How to get the most out of solar battery storage funding

To get the most out of solar battery storage funding, it is important to compare quotes from multiple installers and to choose a system that is eligible for the funding program that you are applying to. You should also make sure that you have a good understanding of the terms and conditions of the funding program before you apply.

The battery storage installation process for businesses

The installation process for battery storage within a commercial business site can typically be broken down into the following steps:

  1. Site assessment: The solar installer will visit your business to perform an assessment. They will review the suitability of your roof for solar panels to determine the best location for your battery system. They will also take into account your business’s energy needs and consumption patterns when designing the system.
  2. System design: Once the site assessment is complete, the solar installer will design a system that meets your business’s specific needs. The design will include the number, type, and size of solar panels. It will also include the size and capacity of the battery system, and the necessary electrical components.
  3. Permitting and approval: In most cases, you will need to obtain a permit from your local government before installing a solar battery storage system. The solar installer can help you with the permitting process.
  4. Equipment procurement: Once the permit is in place, the solar installer will order the necessary equipment. This includes the solar panels, battery system, and electrical components.
  5. Installation: The solar installer will install the solar panels and battery system at your business. The installation process typically takes one to two days.
  6. Testing and commissioning: Once the solar panel and battery system are installed, the solar installer will test the system to make sure that it is working properly. They will also train you on how to use the system.

Once the system is installed and commissioned, you can start using solar energy to power your business. You can also store excess solar energy for later use. This can help you to reduce your energy costs, improve your energy resilience, and reduce your carbon footprint.

Why choose Wattstor for your solar storage needs?

At Wattstor, we believe that renewable electricity is a business essential. We’re committed to eliminating all obstacles to the clean energy transition. We help remove Capex costs, secure lower than grid electricity prices on your renewable projects, and overcome grid constraints.

From fully financed energy systems to industry-leading expertise, we help bring your organisation’s clean energy ambitions to life. We want to make your renewable generation assets go further. This means maximising generation capacity and overcoming grid constraints with state-of-the-art battery storage. Our fully automated EMS, Podium, plans ahead. It oversees all generation assets and makes smart load shifting decisions without human intervention. This removes all guesswork from commercial energy management and allows you to focus on operations.

With energy management taken care of, you’ll be able to stop worrying about electricity bills and start focusing on business.

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