A battery energy storage system (BESS) stores electricity so a business can use it later, typically surplus solar generation or cheaper off-peak grid power. Paired with commercial solar PV, battery storage raises on-site self-consumption, cuts peak-time costs and can work around grid connection limits. Using one installer for both reduces integration risk and gives a single point of accountability.
This guide is for UK businesses weighing up commercial battery energy storage systems alongside solar. It explains how storage works with PV, what it costs, which tax reliefs apply in 2026, what limits it, and how to choose a business solar battery storage installer.
Key takeaways
- A battery energy storage system stores surplus solar or off-peak grid electricity and releases it when it is worth more to the site, measured in kW (power) and kWh (energy).
- Storage adds value because UK non-domestic electricity averaged 24.14p/kWh in Q1 2026 (DESNZ), well above typical export rates, so self-consumed solar is usually worth more than exported solar.
- The strongest cases are sites with evening or extended-hours demand, high peaks, EV charging plans or constrained grid connections.
- Backup power is not automatic. It requires island-mode design and isolation, and should be specified at the feasibility stage.
- Batteries have real limitations, including round-trip losses, degradation and a shorter life than solar panels, which a credible financial model must include.
- In 2026, solar panels qualify for AIA and the 50% special rate allowance but not full expensing; battery treatment can differ, and onsite generation and storage are exempt from business rates in England until March 2035.
- One installer for solar and storage means one design, one G99 application, one warranty picture and one aftercare team.
What is a battery energy storage system for business?
A battery energy storage system for business is a commercial-scale installation of battery modules, power electronics and control software that charges when electricity is cheap or surplus, and discharges when it is expensive or needed. Most new commercial systems use lithium iron phosphate (LFP) cells. Size is described in two numbers: power in kilowatts (kW) and energy capacity in kilowatt-hours (kWh).
| Term |
What it means |
Why it matters to a business |
| Power (kW) |
How fast the battery can charge or discharge |
Determines how much peak demand the battery can cover at once |
| Energy (kWh) |
How much electricity the battery can hold |
Determines how long it can cover that demand |
| Duration |
Energy ÷ power (for example, 500kW / 1,000kWh = 2 hours) |
Should match the length of your peak-price periods or outage cover needs |
| Behind the meter |
Battery connected on the customer's side of the meter |
Serves the site first; can also provide grid services |
| Grid-scale / front of meter |
Battery connected directly to the network |
Earns income from grid services and trading only |
Most commercial and industrial sites install behind-the-meter systems. EvoEnergy also builds grid-scale storage, such as the 20MW/40MWh Hawkers Hill battery storage project, which gives its engineers experience across both ends of the market.
How does battery storage work with commercial solar PV?
Battery storage works with commercial solar PV by capturing generation that the site cannot use at the moment it is produced, then releasing it later in the day. An energy management system (EMS) decides when to charge and discharge based on live generation, site demand and tariff periods.
There are two main integration designs:
- AC-coupled systems connect the battery through its own inverter on the AC side of the site’s electrical system. This is usually the simplest way to add a battery to an existing solar array, and it lets solar and storage be sized independently.
- DC-coupled systems connect the battery on the DC side of a hybrid inverter shared with the solar array. This can reduce conversion losses and equipment count on new-build projects, but it ties the battery design more closely to the PV design.
Note: The right coupling method depends on whether the solar already exists, the site’s electrical infrastructure and the export limit agreed with the Distribution Network Operator (DNO). This is one of the first decisions an integrated installer makes, and it affects cost, efficiency and future expansion.
Why are UK businesses adding battery storage to solar?
UK businesses are adding battery storage to solar because electricity bought from the grid costs far more than electricity exported to it. Every kilowatt-hour of solar a site stores and uses itself avoids a full retail unit price; every kilowatt-hour exported earns only an export tariff. Storage shifts more of each day’s generation into the first category.
According to the Department for Energy Security and Net Zero (DESNZ), the average non-domestic electricity price including Climate Change Levy was 24.14p/kWh in January to March 2026, down 6.2% on a year earlier. Prices have eased from the 2022 to 2023 peak but remain well above pre-crisis levels. Export payments under the Smart Export Guarantee (SEG), by contrast, are set by each supplier and are typically a fraction of import prices.
Why it matters?
Solar generation peaks around midday, while many sites have demand that continues into the late afternoon and evening, when time-of-use tariffs and distribution network charges (DUoS red band periods, whose exact times vary by DNO region) are often highest. Without storage, midday surplus is exported cheaply and evening demand is bought expensively.
Which businesses benefit most from solar battery storage?
Solar battery storage delivers the most value on sites where solar generation and demand do not line up, or where grid capacity is limited. Typical examples include:
- Sites with evening or extended-hours demand, such as hotels, hospitals and 24-hour logistics operations.
- Sites with high peak loads, such as factories and manufacturing with shift patterns or large motors.
- Sites where downtime is expensive, such as cold storage, data rooms and healthcare, provided the system is designed for backup (see below).
- Sites adding EV charging, where EV charging for fleets and workplaces would otherwise exceed the existing grid connection.
- Sites with a constrained or export-limited connection, where the DNO restricts how much solar can be exported.
Battery storage is less likely to pay back where a site already uses almost all of its solar generation during the day, has flat tariffs with little peak/off-peak difference, or has very low overall consumption.
What are the benefits of battery energy storage systems for solar?
Battery energy storage systems add four main types of value to commercial solar: higher self-consumption, lower peak-time costs, the ability to work within grid limits, and, where designed for it, backup power and grid services income. Most sites earn from more than one of these at once, which is why the business case needs to be modelled against real half-hourly data.
1. Using more of the solar power you generate
Battery storage captures surplus solar generated during sunny periods and makes it available later, rather than exporting it at low rates. Businesses can draw on stored energy in the evening, during peak tariff hours, or when solar output drops because of cloud cover. This raises the proportion of solar used on site, which is where each kilowatt-hour is worth the most.
2. Cutting peak-time electricity costs
A battery can reduce costs through two related strategies:
- Load shifting: charging from surplus solar or cheaper off-peak grid electricity, then discharging during higher-priced periods.
- Peak shaving: discharging to cap the site’s maximum demand from the grid during short spikes, which can reduce capacity-related charges and avoid breaching the site’s agreed supply capacity.
Both strategies depend on your tariff and network charges, so an installer should model them using your supplier bills and half-hourly meter data rather than generic assumptions.
3. Working within grid connection limits
Battery storage lets a site use more solar and electrical load than its grid connection alone would allow. The battery absorbs solar that cannot be exported under a DNO export limit and supplies demand peaks that would otherwise exceed the import capacity.
At Stourton Park & Ride in Leeds, EvoEnergy combined 1.2MWp of solar carports, a 500kW/950kWh battery and 26 EV charging units to overcome a 400kW grid-constrained connection. It became the first fully solar-powered park and ride in the UK.
For sites facing long waits or high costs for a grid upgrade, storage can be a faster and cheaper route to adding solar, EV charging or new equipment.
4. Backup power and site resilience
A battery can keep essential loads running during a grid outage, but only if the system is specifically designed to do so. By default, grid-connected solar and battery inverters must shut down when the grid fails, to protect network engineers. Backup operation requires island-mode capable equipment, a safe means of isolating the site from the network, and a decision about which circuits the battery will support.
For cold storage, manufacturing and healthcare sites, short interruptions can spoil stock, halt production lines or disrupt critical services. The updated IET Code of Practice for Electrical Energy Storage Systems (3rd edition, 2024) includes revised requirements for island-mode isolation, which is why backup design should be specified by the installer from the start rather than added later.
5. Grid services and flexibility income
A behind-the-meter battery can earn additional income by responding to signals from the electricity system, for example by reducing grid import or exporting at times of system stress. Routes include flexibility services procured by DNOs and the National Energy System Operator (NESO), usually accessed through an aggregator.
At Lyreco’s 24-hour distribution site in Telford, EvoEnergy followed a large rooftop solar installation with a battery system that provides sub-second frequency response to the grid while also supporting the site’s own demand. At the York Hyperhub, a Tesla battery (348kW/507kWh) paired with 110kWp of solar canopies was set up to offer demand-side response and grid services to Northern Powergrid while powering EV charging.
Grid services income varies with market conditions and should be treated as upside in a business case, not the foundation of it, unless contracted.
What are the limitations of commercial battery storage?
Commercial battery storage is not suitable or cost-effective for every site. The main limitations are energy losses, gradual capacity degradation, space and fire safety requirements, and the fact that value depends heavily on tariffs and usage patterns that can change over the system’s life.
| Limitation |
What it means in practice |
How a good installer manages it |
| Round-trip losses |
Some energy is lost in each charge and discharge cycle |
Compares manufacturers' published round-trip efficiency and models it in savings |
| Degradation |
Usable capacity falls over time and with cycling |
Sizes for end-of-warranty capacity; plans augmentation or replacement in the financial model |
| Shorter life than solar |
Solar panels are commonly modelled over 25+ years; batteries typically need replacing or augmenting within that period |
Includes replacement cost in lifetime returns |
| Space and location |
Commercial systems need suitable indoor or outdoor space, ventilation or cooling, and access |
Assesses siting, separation distances and structural loads at survey stage |
| Fire safety and insurance |
Lithium-ion systems require appropriate fire risk assessment, detection and separation |
Designs to the IET Code of Practice and engages the site's insurer early |
| Tariff dependence |
Savings rely on price differences between periods and between import and export |
Stress-tests the model against different tariff scenarios |
| Grid approval |
Batteries count as generation for DNO purposes |
Submits the G99 application early and designs within any export limit |
Note: None of these limitations rules storage out, but each one should appear in a credible proposal. If a quote does not mention degradation, replacement or grid approval, ask why.
How much does battery storage for a UK business cost?
The cost of battery storage for a UK business depends mainly on its energy capacity (kWh), power rating (kW), the integration work needed and whether grid or electrical upgrades are required. Battery hardware prices have fallen sharply, but commercial behind-the-meter systems also carry design, installation, electrical, controls and grid application costs that scale less neatly.
These are benchmarks for large, turnkey systems. They show the direction of travel (lower hardware costs make more commercial projects viable), but a site-specific quote for a smaller behind-the-meter system will be higher per kWh once integration and connection work are included.
What affects the cost of a commercial BESS?
- Capacity and power rating, based on your load profile, solar output and tariff periods.
- Coupling design, AC-coupled retrofit or DC-coupled new-build.
- Electrical infrastructure, including switchgear, cabling, transformers or HV/LV infrastructure upgrades.
- Backup capability, which needs island-mode equipment and isolation.
- Siting and groundworks, such as bases, enclosures, access roads and fire separation.
- Grid connection, including G99 application fees, any DNO witness testing and any reinforcement costs.
- Controls and monitoring, including the energy management system and smart energy management across solar, storage and EV charging.
- Aftercare, including maintenance, monitoring and warranty terms.
What UK tax reliefs and incentives apply to solar and battery storage?
The main UK incentives for commercial solar and battery storage in 2026 are capital allowances, a business rates exemption for onsite generation and storage in England, and export payments under the Smart Export Guarantee. Their value depends on your business structure, location and how the system is owned and financed.
| Incentive |
What it offers |
Key conditions (2026) |
| Annual Investment Allowance (AIA) |
100% deduction in year one on qualifying plant and machinery |
Up to £1 million a year; limit shared across connected businesses |
| 50% special rate first-year allowance |
50% relief in year one on new special rate assets; balance goes into the special rate pool |
Companies only. HMRC lists solar panels as special rate assets |
| Full expensing |
100% first-year relief on new main rate plant and machinery |
Companies only; excludes special rate assets such as solar panels |
| 40% first-year allowance |
40% relief in year one on new main rate assets |
Available from 1 January 2026 to companies and unincorporated businesses, including leased assets |
| Business rates exemption (England) |
Onsite renewable generation and storage plant and machinery exempt from business rates |
Introduced by SI 2022/405; runs from 1 April 2022 to 31 March 2035 |
| Smart Export Guarantee (SEG) |
Payment for exported low-carbon electricity |
Solar PV up to 5MW in Great Britain; suppliers set rates, which must be above zero |
Important points for battery storage:
- Capital allowance treatment can differ between solar panels and batteries. Solar panels are special rate expenditure, so they do not qualify for full expensing or the 40% FYA. Batteries may be classified differently depending on how they are installed and used. Confirm treatment with your tax adviser before committing.
- Writing down allowances on the main pool fell from 18% to 14% from April 2026, which increases the value of claiming first-year reliefs where available.
- SEG and batteries. Having a battery does not prevent SEG eligibility. However, suppliers are not obliged to pay for exported electricity that originally came from the grid, and some will ask how you separate solar exports from grid-charged exports. Ofgem publishes separate guidance on co-locating storage with renewable generation.
- Finance. If upfront capital is limited, CAPEX, PPA, lease-to-own and green loans change how and whether you claim these reliefs.
Why choose one installer for solar and battery storage?
Choosing one installer for solar and battery storage means a single company designs, installs, commissions and maintains the whole system, so the solar array, battery, inverters, controls and grid application are engineered to work together. The main benefits are fewer integration risks, one point of accountability and aftercare from a team that understands the complete system.
- Integrated design. The battery is sized to the solar array’s output and your site’s usage pattern, and the charge and discharge strategy is set in one energy management system.
- Single point of accountability. With one company handling design, installation and maintenance, issues are resolved without disputes between suppliers about whose equipment is at fault.
- One grid application. Solar and storage are submitted to the DNO as a single G99 application with a coherent export limitation design, rather than two applications that may conflict.
- Coordinated delivery. One programme means fewer scheduling conflicts, one set of site works and less disruption.
- Consistent aftercare. Monitoring covers solar, storage and controls together, so underperformance in one part of the system is spotted and fixed quickly.
Single-provider vs multi-provider projects compared
| Factor |
Single-provider project |
Multi-provider project |
| Project timeline |
Typically faster, with centralised project management, one contract and streamlined communication |
Often longer, as coordinating several companies can cause delays and scheduling conflicts |
| Upfront cost |
May be slightly higher initially due to bundled services, but pricing is more predictable with fewer hidden costs |
Can appear cheaper when sourcing components separately, but carries a risk of overruns from misalignment or rework |
| Integration quality |
High. Components are designed, installed and tested to work together by the same provider |
Variable. Depends on how well different providers' systems align; risk of compatibility issues |
| Grid connection (G99) |
One application covering solar and storage, with one export limitation design |
Separate applications may conflict or need resubmission |
| Warranties |
Clear responsibility for system performance as a whole |
Each provider warrants only its own components, which can leave gaps at the interfaces |
| Aftercare and long-term support |
One point of contact for maintenance, warranties and upgrades, with a consistent service history |
Support may be fragmented, making issue resolution slower and more complex |
Which option is best?
- If your priority is speed, quality assurance and convenience, a single-provider approach usually delivers the most predictable outcome.
- If you have in-house electrical engineering expertise and capacity to manage multiple contracts and a grid application, a multi-provider approach may offer upfront savings, but with more coordination risk.
How do you choose a business solar battery storage installer?
Choose a business solar battery storage installer based on proven commercial storage experience, the right certifications for your system size, transparent modelling using your own data, and a clear aftercare offer. Price matters, but a lower quote that omits grid approval, degradation or fire safety design often costs more later.
Questions to ask before appointing an installer:
- Have you delivered commercial solar and battery projects of a similar size? Ask for case studies with kW, kWh and site type.
- Which standards will the design follow? For commercial systems, expect reference to the IET Code of Practice for Electrical Energy Storage Systems and BS 7671. MCS certification (MIS 3012 for batteries) is relevant for systems up to 50kW, and is often needed for SEG eligibility at that scale, but most larger commercial systems fall outside its scope.
- Are you registered with a competent person scheme such as NICEIC or NAPIT for the electrical work?
- Will you model savings from our half-hourly data? Generic assumptions are not enough to size a battery accurately.
- Does the financial model include degradation and battery replacement?
- Who manages the DNO G99 application, and have you allowed for any export limit?
- Is backup power included? If so, which circuits, for how long, and how is island-mode isolation handled?
- What does aftercare include? Look for remote monitoring, planned maintenance, response times and who holds the warranties.
- Which finance options are available? CAPEX, PPA, lease-to-own or green loan.
EvoEnergy provides feasibility and energy consultancy, in-house installation and aftercare, monitoring and maintenance for integrated solar and battery systems across the UK.
Is a solar and battery storage system right for your business?
Battery energy storage systems make commercial solar more valuable by keeping more of each day’s generation on site, reducing exposure to peak-time prices and letting businesses work within grid connection limits.
Whether storage pays back for your site depends on four things: your half-hourly demand profile, your tariff structure, your grid connection capacity and what you need the battery to do, whether that is savings, resilience, EV charging or grid services. Getting those right at the design stage matters more than the price of the battery itself.
Prefer to explore first? Find out more about our commercial battery energy storage systems and commercial rooftop solar PV, compare finance options including CAPEX, PPA, lease-to-own and green loans, or estimate your generation with the Solar Output Calculator.
Frequently Asked Questions
What is the difference between a BESS and a solar battery?
There is no technical difference: a solar battery is a battery energy storage system that is charged mainly from solar PV. “BESS” is the industry term and covers systems charged from solar, the grid or both. Commercial systems are larger and use more complex controls than domestic ones, but the principle is the same.
Can you add battery storage to an existing commercial solar system?
Yes. Most existing commercial solar systems can have battery storage added, usually as an AC-coupled system with its own inverter, so the existing solar equipment does not need replacing. The installer will need to check available space, electrical capacity and the site’s existing DNO approval, as adding a battery normally requires a new or updated G99 application.
Will a battery keep my business running during a power cut?
Only if it is designed for backup. Standard grid-connected systems shut down when the grid fails. To provide backup, the system needs island-mode capable equipment, a safe isolation arrangement and a defined set of essential circuits. Backup capacity also reduces the energy available for daily savings, so the two need balancing.
How long do commercial batteries last?
Commercial lithium iron phosphate batteries typically last well over 10 years, with lifespan measured in both years and charge cycles. Usable capacity declines gradually over time, so warranties usually guarantee a minimum capacity at the end of the warranty period. Because solar panels are commonly modelled over 25 years or more, a lifetime financial model should include battery replacement or augmentation.
Do I need DNO permission to install commercial battery storage?
Yes, in almost all commercial cases. Batteries count as generation, so systems above 16A per phase need approval from the local Distribution Network Operator under the ENA’s G99 process before connection. The DNO may set an export limit, which is managed with a G100 export limitation scheme.
Can I get paid for exporting electricity from my battery?
Yes, potentially. The Smart Export Guarantee pays for exported low-carbon electricity from solar systems up to 5MW, and having a battery does not stop you applying. However, suppliers do not have to pay for exported electricity that came from the grid, so you may need to show how solar exports are separated from grid-charged exports.
What size battery does my business need?
The right battery size depends on your half-hourly demand profile, solar generation, tariff periods and goals. A battery sized only for surplus solar is usually smaller than one also used for off-peak load shifting, peak shaving or backup. Oversizing adds cost without extra savings, so sizing should be based on your own meter data rather than a rule of thumb.
Is battery storage worth it without solar?
It can be. A standalone battery can still save money by charging from cheaper off-peak grid electricity and discharging at peak times, and by reducing peak demand charges. The savings are usually lower than with solar, because there is no free generation to store, so the case depends heavily on your tariff structure.
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About the Author
Paul Lukehurst is a Principal Design Engineer at EvoEnergy, with over 10 years' experience in the renewable energy sector across engineering and leadership roles. His expertise spans the full project lifecycle — from feasibility and financial modelling through to detailed design, procurement, and delivery oversight — ensuring systems are technically sound, buildable, and maintainable.
Solar PV Design
Battery Storage
Grid Connection
EV Charging
Net Zero