Ofgem's guidance says a battery can be added to a Feed-in Tariff installation without ending the accreditation, provided the scheme's metering rules are still met, and that the change must be reported to your FIT licensee. Generation payments continue when the generation meter measures only the solar. Deemed export payments, calculated at 50% of generation for solar, continue for the usual set-ups. Metered export payments can stop if the battery can charge from the grid and the export meter cannot separate the solar export from the rest. Ofgem gives no advance assurance, so ask the installer to confirm in writing which of its scenarios your set-up matches.
Guide · Published by SEO Dons Ltd · Updated 7 October 2026
What Ofgem’s guidance says in one paragraph
The legislation behind the Feed-in Tariff (FIT) does not mention storage, so adding a battery is neither prohibited nor provided for. Ofgem’s co-location guidance, version 6, published on 20 March 2024, says that where the scheme’s requirements continue to be met, storage can be deployed without affecting the accreditation of a FIT installation. It also sets four principles: co-located storage does not change the generator’s obligations; support is paid only on eligible renewable electricity generated by the accredited installation; installing storage does not alter the installation’s total installed capacity; and the type of storage technology does not change the eligibility rules. Ofgem adds that there is no process to get prior assurance that a change will not affect the accreditation: it assesses each change case by case once it has been made and notified.
The three questions that decide the answer
- Is your export deemed or metered? Solar FIT installations of 30 kW or less, where it is not practical to measure export, are paid deemed export: 50% of the generation meter reading for solar. Otherwise the export is read from an export meter.
- Is the battery on the AC or DC side of the generation meter? A typical retrofit is AC-coupled: the battery has its own inverter and is connected after the generation meter, so the generation meter still reads only the panels. A DC-coupled battery that shares an inverter with the panels sits before the meter.
- Can the battery charge from the grid? If it can, the electricity measured by a meter may no longer be only solar.
What Ofgem concludes, scenario by scenario
These are the cases from Ofgem’s guidance that match an ordinary home with on-site demand. The scenario numbers are Ofgem’s.
| Ofgem scenario | Set-up | Generation payments | Export payments |
|---|---|---|---|
| 4.1 | Deemed export; battery after the generation meter (AC-coupled); can charge from the grid | Continue | Deemed export unaffected |
| 4.2 | Metered export; battery after the generation meter; can charge from the grid | Continue | No metered export payments; deemed export could be claimed if its conditions are met |
| 4.4 | Deemed export; battery shares the inverter (DC-coupled); can charge from the grid; bi-directional generation meter | Continue | Deemed export continues |
| 4.6 | Deemed export; DC-coupled; charged only by the solar, with inverter settings preventing grid import | Continue | Deemed export continues |
| 4.7 | Metered export; DC-coupled; can charge from the grid; ordinary meters | None | None |
| 4.8 | Metered export; DC-coupled; can charge from the grid; bi-directional meters; on-site load | Continue | No metered export payments |
| 4.9 | Metered export; DC-coupled; charged only by the solar through a disconnection relay | Continue | Metered export continues |
The pattern is clear. Deemed export plus an AC-coupled retrofit is the safe combination: the generation meter keeps reading only the panels, so both the generation payment and the deemed export payment are unaffected. Metered export is the fragile one: Ofgem says a battery that can charge from the grid stops the export meter from isolating what the panels exported, so no metered export payments can be made, and it points out that a set-up where the battery can only be charged by the solar can keep both. A DC-coupled battery before the generation meter needs either a battery that cannot charge from the grid or a bi-directional meter, and Ofgem notes that most smart meters are not bi-directional meters in its definition.
Three smaller rules worth knowing
- Bi-directional meters calculate monthly. Their readings are the difference between each month’s import and export, unlike the cumulative readings of a standard meter, and if the difference in a month is negative, zero FIT payments could be claimed for that month.
- Losses can cost a little. A set-up that meets the rules may still record less generation, because a battery loses energy charging and discharging, and Ofgem says FIT payments are then likely to be reduced.
- Reporting matters. Ofgem can withdraw an accreditation if the installation is modified in a way that stops it being entitled to it, or if the information it was based on was wrong. Reporting the battery is how the licensee checks it.
What to tell your licensee
Ofgem asks generators to give their FIT licensee an updated single-line or schematic diagram showing how the solar reaches the battery and what the metering arrangements are. If a bi-directional meter is used it also asks for the meter’s make, model and manual, confirmation of how it works with photographic evidence that it displays the net figure, and the MID compliance certificate, plus whether the battery can charge from the grid and the date it became operational. For MCS-scale installations, Appendix 1 of the guidance gives two standard pairs of declarations, one for a battery that cannot charge from the grid (scenario 4.6) and one for a battery that can (scenario 4.1), each signed by the generator and by the installer. A good installer will have these ready; ask for copies for your records.
If you join Octopus Flux
Octopus’s tariff for solar and battery homes has its own rule for FIT customers. Octopus Flux does not require you to move your FIT generation contract, and the generation payments stay the same, but it does require you to opt out of deemed export permanently and take the Flux export rate for every kWh your smart meter records going out. If you later leave Octopus, the export side is paid at the Smart Export Guarantee rate of the new tariff, not the old deemed rate. The rates, the times and who can join are on the Octopus Flux rates page.
Flux is one of five Octopus export tariffs. The Octopus export tariff comparison sets it beside Outgoing Octopus, Prime Outgoing, Agile Outgoing and the Smart Export Guarantee tariff, and notes that Octopus’s own pages describe the Feed-in Tariff rule differently, so ask before you switch.
What to ask the installer
Before signing for a retrofit solar battery on FIT panels, ask for answers in writing to four questions: Is my export deemed or metered? Is the battery AC- or DC-coupled? Can it charge from the grid? And which of Ofgem’s scenarios does that make this installation, with the declarations that go with it? The AC vs DC guide explains the two kinds of coupling, and this guidance is not legal advice: Ofgem says each case is assessed on its merits, so keep copies of everything you send your licensee.
Questions people ask
Will a battery stop my Feed-in Tariff payments?
Not by itself. Ofgem says storage can be co-located with an accredited FIT installation without affecting the accreditation, provided the scheme's requirements are still met. The generation payments are paid on the solar generation meter, so they continue when that meter measures only the solar. What can be lost is the metered export payment, in set-ups where the battery can charge from the grid.
Do I have to tell my Feed-in Tariff supplier about a battery?
Yes. Ofgem says co-locating storage should be reported to the FIT licensee in line with the Statement of FIT Terms. It asks for an updated single-line or schematic diagram showing how the solar reaches the battery and where the meters are, with extra evidence if a bi-directional meter is used. For MCS-scale installations Ofgem publishes standard declarations that the generator and the installer can sign.
What is deemed export and does a battery change it?
Deemed export is the payment for electricity exported from a FIT installation of 30 kW or less where it is not practical to meter the export. For solar it is calculated as 50% of the generation meter reading. Because it uses the generation meter, a battery does not change it as long as that meter still measures only the solar generation.
Can I keep the Feed-in Tariff if I join Octopus Flux?
Yes. Octopus says you do not have to move your FiT generation contract to it, and the generation payments stay the same. You must permanently opt out of deemed export and be paid the Flux export rate for what your smart meter measures. If you leave, export is paid at the Smart Export Guarantee rate of your new tariff.
Do I need a special meter for a battery on Feed-in Tariff solar?
Only in some set-ups. If the battery is wired after the generation meter, which is the usual AC-coupled retrofit, the existing generation meter keeps measuring only the solar. If the battery shares an inverter with the panels (DC-coupled) and can charge from the grid, Ofgem's route is a bi-directional meter that calculates a net generation figure, and most smart meters do not qualify.