Many homes across the UK installed solar panels during the Feed-in Tariff (FiT) era. The scheme, which ran from 2010 until 2019, rewarded homeowners for generating renewable electricity and exporting unused power back to the grid. Thousands of these early solar PV systems are still operating today and continuing to provide clean electricity and long-term income.
As energy use changes and battery technology becomes more accessible, many homeowners with older FiT systems are now exploring ways to store and use more of their solar energy at home. One of the most practical ways to achieve this is through an AC-coupled battery storage system.
At Quantum Electrical Services, we regularly work with homeowners who want to upgrade existing solar installations while ensuring their Feed-in Tariff arrangement remains unaffected.
Understanding the Feed-in Tariff Scheme
The Feed-in Tariff was introduced to encourage renewable electricity generation in homes and small businesses. Under the scheme, eligible solar PV systems receive payments for:
Electricity generated by the solar panels
Electricity exported to the grid
For many early installations, export payments were calculated using a deemed export model, meaning the system assumed that around 50% of generated electricity was exported, regardless of actual usage.
Because of this structure, many FiT system owners benefit financially even if they increase how much of their solar electricity they use themselves.
Why Many FiT Systems Did Not Originally Include Batteries
When Feed-in Tariff installations were first being fitted, domestic battery storage was far less common. Most homes simply exported excess electricity back to the grid during the day and imported electricity again in the evening when solar generation stopped.
Since then, several changes have influenced how solar energy is used in homes:
Household electricity consumption has increased
Electric vehicles are becoming more common
Battery storage technology has become more reliable
Energy prices have changed significantly
As a result, storing solar electricity for later use has become a practical option for many existing solar systems.
What Is an AC-Coupled Battery System?
An AC-coupled battery system connects to the household electrical system on the alternating current (AC) side of the installation rather than directly into the solar panel array.
In a typical setup:
Solar panels generate electricity as DC power.
The solar inverter converts this to AC electricity for use in the home.
The AC-coupled battery monitors household energy use and solar generation.
When excess electricity is available, the battery stores it.
When solar generation stops, the battery supplies electricity back to the home.
Because the battery connects after the solar inverter, it works alongside the existing solar system without altering the original PV installation.
Why AC-Coupled Batteries Work Well with FiT Systems
For homes receiving Feed-in Tariff payments, maintaining the integrity of the original system is important. AC-coupled batteries are often preferred because they can be added without modifying the generation equipment that the FiT agreement is based on.
Advantages include:
The original solar inverter and system configuration remain unchanged
The generation meter continues to record solar production accurately
The battery operates independently of the FiT system
Installation is usually simpler than redesigning the solar array
This makes AC-coupled storage one of the most common approaches when upgrading older solar installations.
Increasing Self-Consumption of Solar Energy
One of the main reasons homeowners add batteries to existing solar systems is to increase self-consumption.
Without storage, solar electricity generated during the day may be exported even if the home needs electricity later in the evening. A battery allows excess energy to be stored and used later for:
Lighting and appliances
Cooking and home electronics
Electric vehicle charging
Overnight electricity demand
This means more of the electricity generated on the roof is used within the home rather than drawn from the grid.
Compatibility with Future Energy Technologies
AC-coupled battery systems can also support other technologies that are becoming increasingly common in UK homes.
These include:
Electric vehicle charging
Time-of-use electricity tariffs
Home energy management systems
Integration with existing solar PV systems
Because the battery connects to the household electrical system rather than the solar array itself, it can respond to overall household energy flow rather than just solar generation.
Electrical Safety and Compliance
Any battery installation must comply with current electrical standards and safety requirements.
Professional installation includes:
Correct protective device selection
Safe integration with the consumer unit
Appropriate isolation and switching equipment
Compliance with BS 7671 wiring regulations
Testing and certification of the installation
These steps ensure the battery system operates safely alongside the existing solar equipment.
Upgrading an Existing Solar System
Many Feed-in Tariff solar installations were designed more than a decade ago. While the panels themselves often continue performing well, upgrading the system with battery storage can allow homeowners to make better use of the electricity they generate.
Because AC-coupled systems do not require alteration of the original PV system, they are often the most practical solution for adding storage to an existing installation.
Considering a Battery Upgrade for Your Solar Panels?
If you have a Feed-in Tariff solar system and are exploring ways to store more of your solar energy, a professional assessment can help determine whether battery storage is suitable for your property.
Quantum Electrical Services provides solar PV and battery installation services across Sleaford and surrounding Lincolnshire villages, helping homeowners integrate modern energy storage with existing renewable systems safely and effectively.
If you would like to learn more about battery storage for existing solar panels, contact our team to discuss the options available for your home.
