What Is a Battery Energy Storage System (BESS)?

A Battery Energy Storage System (BESS) stores electricity in high-capacity, rechargeable battery modules, typically using lithium-ion or LFP (LiFePO₄) technologies. This stored energy can be used when grid prices are high, during power interruptions, or to support load shifting in commercial installations.

The term BESS refers to integrated battery-based energy storage systems used across both residential and commercial applications. However, it is more commonly used in commercial and industrial contexts. In residential settings, terms like solar battery or home battery storage are typically preferred.

This page focuses on commercial battery storage systems and their benefits for UK installers and energy users.

How Does a Commercial BESS Work?

A BESS captures surplus electricity from solar PV systems or from the grid and stores it for later use. This is typically during peak demand periods, overnight, or during grid outages when energy costs are high or supply is limited.

Key BESS Components:

Battery Modules: Store electrical energy (usually lithium-ion or LFP).
Power Conversion System (PCS): Manages DC–AC conversion for grid or onsite use.
Battery Management System (BMS): Ensures safe operation and monitors temperature, voltage, and cell health.
Energy Management System (EMS): Optimises charging/discharging based on demand, pricing, or grid signals.
Monitoring Interface: Allows for remote tracking, diagnostics, and control.

Advanced EMS features like peak shaving, load shifting, and grid participation unlock both energy savings and new revenue streams.

Why BESS Matters to UK Solar Installers

BESS is fast becoming standard in commercial and industrial (C&I) solar projects across the UK. As of April 2025, the UK had 124 operational BESS installations totaling 2.6 GW, plus 930 under construction or with planning consent.

Businesses are turning to battery storage to reduce energy costs, improve self-consumption, and access new revenue through grid flexibility services.

Core Benefits for Commercial Clients:

Lower Energy Bills: Use stored energy when tariffs are highest.
Increased PV ROI: Maximise on-site solar generation and reduce export.
Grid Services Income: Participate in schemes like Dynamic Containment or Demand Side Response (DSR).
Backup Power: Maintain operations during outages or grid failures.
Decarbonisation: Enable a smoother transition to clean energy.

Battery Storage Applications in Commercial Solar Projects

Commercial BESS allows businesses to improve control over their energy consumption while protecting against price volatility and supply issues.

Common commercial applications include:

Warehouses and logistics centres
Large-scale EV charging sites
Public sector buildings and education
Farms and rural energy setups
Retail parks and office buildings with PV

Battery storage helps align on-site renewable generation with energy demand, reduce grid dependency, and ensures reliable power during grid disruptions. It also supports peak demand reduction and enables participation in energy trading and flexibility markets.

BESS Right for Your Commercial Project?

If your business or client site has a high energy load, uses solar PV, or wants to reduce grid reliance, then BESS can offer significant value. It’s also ideal for organisations looking to generate new revenue by participating in energy flexibility markets.

However, successful implementation depends on factors such as:

Load profile and consumption patterns
Battery size and CapEx budget
Grid constraints and connection capacity
Target payback period

Commercial Incentives and Financial Benefits?

Some financial mechanisms support commercial battery storage investment in the UK.

0% VAT on Commercial Battery Storage (until March 2027).
Smart Export Guarantee (SEG): commercial systems can earn for exporting stored energy via eligible tariffs.
Local & Regional Green Grants: councils and regional funds offer matched funding for commercial clean-energy upgrades.
Tax Relief (Capital Allowances): businesses can deduct 100% of BESS costs from taxable profits.
Green Finance Options: low-interest commercial loans and clean-tech financing for SME projects.
Grid services revenue: Commercial BESS systems can participate in grid flexibility and ancillary markets, including demand-side response (DSR), dynamic containment, and frequency response schemes.

From 2025, Ofgem will launch a Cap and Floor Revenue Support Scheme for long-duration electricity storage (LDES). While targeted at utility-scale systems, the policy signals long-term government support for battery storage infrastructure, which may extend to larger commercial sites.

When Battery Storage Makes Sense for a Site?

Commercial BESS systems are most effective in projects where:

Energy consumption is high or concentrated during the day or early evening
On-site solar generation is in place and self-consumption can be improved
The site is exposed to peak electricity tariffs, grid constraints, or supply risks
Backup power is needed to maintain critical operations
There is interest in participating in grid flexibility or energy trading schemes

Successful deployment depends on several key factors:

Load profile, usage patterns, and available grid connection capacity
Battery size, capital expenditure (CapEx) budget, and target payback period

Commercial Battery Systems from Leading Manufacturers

Alternergy supplies advanced battery systems from trusted manufacturers including Huawei, Sungrow, and Dunext.

All solutions include full documentation, monitoring, and technical support from design to commissioning.

➛ Explore our Commercial Battery Solutions

➛ Explore our Residential and Commercial Solar Battery Storage Systems

➛ Browse our Commercial Battery Glossary to find clear definitions

Need Support?

If you're a UK installer looking to integrate battery storage into commercial projects, we're here to help.

Frequently Asked Questions

What is a BESS battery energy system?

A BESS (Battery Energy Storage System) is an integrated solution that stores electricity in rechargeable batteries for later use, typically to reduce energy costs, provide backup power, and support grid flexibility.

What does a battery storage system do?

A battery storage system stores surplus electricity, often from solar panels or the grid, for use when demand is high, during outages, or when tariffs are most expensive.

What is the difference between a battery and a BESS?

A battery is the energy storage component, while a BESS includes the battery (or batteries) along with power conversion, management, and monitoring systems for complete operation.

How long does a BESS battery last?

A typical BESS battery lasts 10 to 15 years, depending on the chemistry, usage patterns, environmental conditions, and maintenance. Lithium-ion batteries - particularly lithium iron phosphate (LiFePO₄ or LFP), which are commonly used in BESS - tend to offer longer lifespans.

Can you have battery storage without solar?

Yes, battery storage can operate without solar. It can charge from the grid and discharge during peak demand or power outages to reduce costs and increase resilience.

Can BESS batteries be recycled?

Yes, most BESS batteries, especially lithium-ion, are recyclable. Specialist recycling firms recover materials like lithium, nickel, and cobalt to reduce environmental impact.

What are the risks of battery energy storage system fire?

Fire risks in BESS typically arise from thermal runaway, poor installation, or damaged cells. Modern systems include thermal monitoring, safety cut-offs, and fire suppression to reduce risk.

What is the difference between a BESS battery vs a battery backup unit?

A BESS is designed for full energy management and grid participation, while a battery backup unit is usually smaller and only provides temporary power during outages.

Do you have to notify DNO for battery storage?

Yes, in most cases, you must notify the Distribution Network Operator (DNO) before connecting a BESS to the grid, especially for larger commercial systems.

What kind of batteries are used for BESS?

BESS commonly use lithium-ion (refers to any battery that uses lithium ions such as LiFePO₄ (LFP) and LiNiMnCoO₂ (NMC)) batteries, lead-acid, and flow batteries, selected based on project size, budget, and performance requirements.

Can BESS help installers add value to PV systems?

Yes, adding BESS to a PV system increases self-consumption, lowers grid export losses, enables backup power, and opens new revenue through grid services.

Do BESS systems need maintenance?

Yes, BESS systems require regular maintenance including system checks, firmware updates, and battery health monitoring to ensure safety and long-term performance.