As the UK enters a new phase of plug-in solar adoption, the opportunity for residential energy storage is expanding beyond traditional rooftop solar installations.

BST POWER has introduced the PT-SG-AC 3.5/2.4, a modular AC-coupled balcony energy storage system designed to help households store solar energy, increase self-consumption and manage electricity use more intelligently.

The UK government confirmed that compliant plug-in solar products can be legally used from 27 August 2026, subject to the applicable regulatory framework and the DESNZ Interim Product Specification.

The new framework is specifically focused on plug-in solar microgeneration and does not cover plug-in battery systems.

For the growing UK balcony solar and residential solar market, this distinction highlights an important opportunity: solar generation is only part of the energy equation.

The ability to store and use electricity at the right time can further improve household energy utilisation.

Designed for AC-Coupled Solar Battery Storage

The BST POWER PT-SG-AC 3.5/2.4 is an AC-coupled battery energy storage system developed for residential and balcony solar applications.

Unlike DC-coupled storage systems that are integrated into the solar generation side, an AC-coupled battery can be added to an existing PV installation through the AC side.

This makes the architecture suitable for solar retrofit projects, where homeowners may want to add energy storage without replacing their existing solar equipment.

Each unit provides:

• 3.5 kWh battery capacity

• 2.4 kW AC output

• LiFePO₄ battery chemistry

• 6,000+ cycle life

• 15-year design life

• IP65 protection

• Stackable modular architecture

• AC-coupled compatibility with existing PV systems

The modular design allows households and installers to configure storage capacity according to actual energy consumption, installation requirements and future expansion plans.

Why Energy Storage Matters for the UK Balcony Solar Market

The UK plug-in solar market entered a new regulatory phase on 27 August 2026, when the relevant amendments supporting compliant plug-in solar microgenerators came into force.

Government information states that plug-in solar products can provide an accessible route for households to generate electricity, particularly where conventional rooftop solar installation may be more difficult.

However, solar generation does not always match household electricity demand.

Solar production is typically highest during daylight hours, while household electricity consumption can increase during the evening. This creates a natural role for battery storage:

Solar generation → Battery storage → Smart energy management → Household consumption

By storing available energy and releasing it when electricity demand is higher, an AC-coupled battery system can help increase solar self-consumption and reduce reliance on grid electricity.

For installers, distributors and energy brands, this creates an additional product category around the expanding UK balcony solar and residential energy storage market.

Smart Meter Integration for Dynamic Energy Management

One of the key features of the PT-SG-AC 3.5/2.4 is its focus on real-time energy monitoring and intelligent control.

The system supports compatibility with multiple meter solutions, including:

• Shelly

• EcoTracker

• Tibber Pulse

• PI-Meter

The wireless meter reader supports infrared and P1 reading, with communication through Wi-Fi and LoRa.

This allows the system to acquire real-time electricity consumption information and use it for intelligent energy management.

For markets where dynamic electricity tariffs are available, real-time energy data can be combined with tariff information to help determine when the battery should charge or discharge.

Smart Charging During Lower-Cost Periods

When electricity prices are lower, the system can schedule battery charging according to the configured energy strategy.

Discharging During Higher-Demand Periods

During periods of higher electricity demand or higher electricity prices, stored energy can be used to supply household loads.

Self-Consumption Optimisation

The system can also support self-consumption strategies designed to increase the proportion of locally generated energy used within the home.

These functions are managed through BST Cloud and the BST App, giving users and installers access to system information and energy management functions.

Smart Home and HA-EMS Integration

The PT-SG-AC 3.5/2.4 is designed to work with smart energy management environments, including Home Assistant (HA) and HA-EMS.

The system supports:

• AI-based energy monitoring

• Energy forecasting

• Dynamic tariff management

• Time-of-use energy management

• Self-consumption control

• Backup-mode configuration

• Smart meter integration

• Remote monitoring through BST Cloud

• App-based system management

For installers and energy solution providers, this provides flexibility when integrating the battery into different residential energy management architectures.

The system also includes a LAN communication port, providing a wired communication option where a stable network connection is preferred over Wi-Fi.

Intelligent Export and Power Control

For residential solar systems connected to the grid, controlling energy flow is an important part of system management.

With smart meter data and intelligent control, the PT-SG-AC 3.5/2.4 can monitor household power demand and coordinate battery operation accordingly.

This supports export control and self-consumption management, helping installers design residential energy storage systems around the requirements of different markets and grid environments.

Rather than simply storing electricity, the system is designed to coordinate:

PV generation + household consumption + battery storage + electricity tariffs + grid power

This approach transforms a conventional battery into a more connected residential energy management solution.

Compact, Modular and Suitable for Balcony Energy Storage

Balcony energy storage places different demands on a battery system compared with conventional utility-room installations.

Space can be limited, particularly in apartments, flats and smaller residential properties.

The PT-SG-AC 3.5/2.4 therefore uses a compact, stackable architecture that allows storage capacity to be expanded without requiring a large dedicated battery room.

The system is designed around:

• Stackable modular installation

• Compact residential footprint

• AC-coupled architecture

• IP65 protection

• LiFePO₄ battery chemistry

• Outdoor residential applications

• Flexible system expansion

This makes the platform suitable for balcony solar, apartment energy storage, residential solar retrofit and

small-scale home energy storage projects, subject to local installation requirements.

Built for OEM, ODM and Private-Label Energy Brands

Beyond the standard product, BST POWER provides OEM, ODM and private-label solutions for energy storage companies, distributors, installers and residential energy brands.

Customization can include:

• Product branding

• Housing and appearance

• Packaging

• App interface

• Cloud platform

• Product functions

• Communication configuration

• Energy management integration

This allows partners to develop a branded AC-coupled balcony battery solution without building the complete hardware, software and cloud infrastructure from the ground up.

PT-SG-AC 3.5/2.4 Key Specifications

A New Opportunity for UK Balcony Solar and Residential ESS

The UK's plug-in solar market is developing rapidly, creating new opportunities for manufacturers, distributors and installers across the residential energy sector.

The government has positioned plug-in solar as an accessible route for households to generate electricity, while also emphasising the importance of product compliance and electrical safety.

For energy storage companies, the opportunity extends beyond solar generation itself.

As more households adopt smaller-scale solar systems, AC-coupled battery storage, smart meters, dynamic tariffs and home energy management systems can become important components of the broader residential energy ecosystem.

The PT-SG-AC 3.5/2.4 is designed for this transition — combining modular battery storage, smart meter connectivity, intelligent energy management and OEM/ODM flexibility in one residential ESS platform.

Partner with BST POWER

BST POWER is a China-based residential energy storage OEM/ODM manufacturer specialising in balcony energy storage, AC-coupled ESS, residential batteries and integrated home energy solutions.

The PT-SG-AC 3.5/2.4 is available for qualified distributors, installers, energy brands and private-label partners in the UK, Europe and other international markets.

Looking for an OEM/ODM balcony battery or AC-coupled residential ESS for your market?

Contact BST POWER to discuss product configuration, samples, certification documentation and private-label solutions.