Adding a battery to an existing solar PV system does not normally cancel your Feed-in Tariff (FIT) accreditation. Ofgem’s current guidance says battery storage may be added without affecting accreditation, but the system must continue to meet the FIT metering rules. The installation and paperwork therefore matter just as much as the battery itself.
For most domestic FIT systems, a properly designed retrofit lets you keep receiving generation payments while storing more of your solar electricity for use later. Before work starts, the installer should understand where the existing generation meter sits, whether your export is deemed or metered, and what your FIT licensee needs to be told.
What Ofgem says about adding battery storage
The answer is set out in Ofgem’s April 2026 guidance for FIT generators. It states that battery storage may be added to a FIT-accredited installation without affecting its accreditation. The important condition is that the installation must continue to comply with the scheme’s metering criteria.
That distinction matters. A battery is not automatically a problem for FIT. The risk comes from an unsuitable electrical arrangement that allows imported electricity or battery discharge to be counted as eligible solar generation, or from failing to document a change to the accredited installation.
Generation payments and export payments are different
FIT payments can have two parts:
- Generation payments are based on the electricity produced by the accredited solar installation and recorded by its generation meter.
- Export payments relate to electricity sent to the grid. These may be based on actual export readings or a deemed percentage of generation, depending on the arrangement.
Ofgem confirms that the FIT scheme pays for electricity generated and exported by accredited installations. The scheme closed to new applicants on 1 April 2019, but existing accredited installations continue under their agreed eligibility period. You can read the regulator’s overview on the Ofgem FIT scheme page.
A battery changes what happens to surplus electricity after it has been generated. Instead of immediately flowing to the grid, some of it can be stored and used in the evening. That does not have to change the solar generation reading.
Why the battery connection point matters
An AC-coupled battery is a common way to retrofit storage to an older FIT system. It has its own battery inverter and can usually be added without replacing the existing solar inverter. The battery equipment is connected on the house side of the FIT generation meter, so that meter continues to record the output from the accredited solar PV system rather than energy discharged by the battery.
This can be useful when the original solar inverter is still working well or is from a different manufacturer. It also allows a suitably designed system to charge from cheaper off-peak electricity as well as surplus solar.
A DC-coupled or hybrid arrangement may also be possible, but it can involve replacing the solar inverter or changing how generation is measured. That does not make it unsuitable; it means the installer must confirm that the proposed metering and equipment changes remain compliant with your FIT agreement. Our battery storage retrofit service is designed around the solar equipment and metering already at the property.
Can the battery charge from the grid?
Yes, provided the system is designed and metered correctly. Grid charging can be useful on a time-of-use tariff, particularly during winter when there may not be enough surplus solar to fill the battery.
The key FIT rule is that imported electricity must not be presented as generation from the accredited solar panels. In a straightforward AC-coupled retrofit, the original generation meter remains dedicated to the solar inverter. More complex layouts may need an acceptable bidirectional meter that can calculate net renewable generation. Ofgem’s guidance explains the information a FIT licensee may require where such a meter is used.
If you plan to combine stored solar with cheap overnight electricity, our guide to battery storage without relying on solar generation explains the practical difference between battery capacity, charge rate and usable energy.
What happens to FIT export payments?
First check whether your FIT export payment is deemed or metered. Many smaller domestic installations receive deemed export payments: the payment is calculated from a set proportion of recorded generation rather than a reading of the electricity actually exported. If that remains your approved arrangement, storing more solar does not automatically reduce the deemed export calculation.
If you are paid for measured export, a battery may reduce the number of kilowatt-hours recorded as exported because more surplus is retained for use in the home. That could reduce the export payment, while also reducing electricity bought from the grid. The useful comparison is the value of each stored kilowatt-hour avoided from your import bill against the export income you give up, allowing for battery losses and the tariff terms.
It is also possible to retain FIT generation payments while opting out of the FIT export payment and joining a Smart Export Guarantee tariff for the same capacity. Ofgem says you must opt out of FIT export before receiving SEG export payments for that installation; you do not have to give up FIT generation payments.
Tell your FIT licensee about the change
Ofgem says co-located battery storage should be reported to the FIT licensee in accordance with the Statement of FIT Terms. For a typical MCS-FIT domestic installation, the licensee is the energy company that administers the FIT payments.
The information may include an updated single-line diagram showing the battery and meters, the meter readings used for FIT claims, details of the storage equipment, and evidence of its installation and commissioning date. MCS-FIT generators should also submit the relevant declaration forms. Your installer should leave you with the documents needed to explain the final arrangement clearly.
Ofgem also recommends using an MCS installer for battery systems up to 50 kW and installing in line with the MCS battery standard. You can verify an installer through the official MCS installer directory.
What to have ready before requesting a quote
A useful battery survey starts with the existing system, not a battery model. Have your FIT statement, MCS certificate if available, recent generation meter reading, solar inverter details and a photo of the consumer unit ready. Annual electricity use and half-hourly smart-meter data can also help with sizing.
Decide whether the main aim is to store daytime solar, charge overnight, support an EV, or provide limited backup during a power cut. Those are different requirements. A battery does not automatically keep the whole house running during an outage; our guide to solar panels and battery backup in a power cut explains the extra equipment and circuit planning involved.
Installed electrical battery storage in residential accommodation currently qualifies for zero-rate VAT. HMRC’s VAT Notice 708/6 says the temporary zero rate runs until 31 March 2027, after which qualifying installations revert to the 5% reduced rate. A battery bought as equipment without installation is treated differently.
The practical answer for FIT owners
You can normally add a home battery without losing your Feed-in Tariff accreditation or generation payments. The safest route is a design that preserves accurate measurement of the accredited solar generation, accounts properly for any grid charging, and gives your FIT licensee the information it requires.
If you have an existing FIT solar system in Nuneaton, Warwickshire, Leicester, Leicestershire or the wider Midlands, contact Sunergy Renewables. We can review the inverter, generation meter, electricity use and backup requirements before recommending a retrofit battery arrangement.
