Will a battery affect my FIT or SEG payments?
It can, and the deciding factor is one most quotes never mention: whether the battery can charge from the grid, and where the meter sits. Get it wrong on a metered-export FIT installation and the export payments stop.
One question decides most of it: can the battery charge from the grid?
If it can, the electricity leaving your house is a mixture, and neither scheme pays for units that did not come from the solar. Where the meters cannot separate them, payments can stop. Where they can, nothing changes — but you and your installer have paperwork to file.
Why this exists at all
Both schemes pay for electricity from an accredited renewable installation. A battery breaks the assumption they were written on, because a battery that can charge from the grid turns exported electricity into a mixture: some of it generated by your panels, some of it bought from a supplier, stored, and sold back.
Ofgem’s word for the second kind is brown export. The schemes were not built to pay for it, and the guidance is largely a set of rules about when a meter can tell the two apart.
Ofgem publishes this as Guidance for generators: Co-location of electricity storage and hydrogen production under the RO, FIT, REGO and SEG. The current version is 6.2, published 23 May 2025.
If you are on the Feed-in Tariff
Most domestic FIT installations are on deemed export: for an installation with a total installed capacity of 30 kW or less, export is not measured but taken as a fixed percentage of the generation meter reading — 50% for solar PV.
That turns out to be good news, because deemed export is calculated from the generation meter. Ofgem’s position:
As deemed export payments are calculated using the generation meter reading, where it is possible to be satisfied the generation meter measures only the generation from the accredited FIT installation, deemed export payments can be made. This remains the case for FIT installations with co-located storage.
So the test is not whether you have a battery. It is whether the generation meter still reads only what the panels produced — either because it sits between the array and the battery, or because it is a bi-directional meter that can net out what went the other way.
If your FIT installation is on metered export rather than deemed export, and the storage sits after the generation meter with meters that cannot measure a net value, Ofgem is explicit: the export meter measures the combined export, some of which may have come from the grid, so no metered export payments can be made.
Generation payments can still be made in that scenario. The export half of the income stops.
And there is a worse case. If the generation meter itself cannot produce a reading of the electricity generated only by the FIT installation, then generation payments go too:
If it is not possible to be satisfied that the generation meter produces a reading of the electricity generated only by the FIT installation, then the generator will not be entitled to receive generation payments.
The declarations you have to make
This is the part almost nobody mentions before the battery is on the wall. Ofgem’s appendix sets out declarations for the two most common domestic arrangements, and both the generator and the installer sign.
If the battery cannot charge from the grid — Declarations 1a and 1b. You certify that the co-located storage system cannot charge from the grid. Your installer certifies the same, names the model and manufacturer, gives the installation date and address, and attaches a single line or schematic diagram showing how electricity reaches the storage and what the metering arrangements are.
If the battery can charge from the grid — Declarations 2a and 2b, which additionally require you to confirm where the generation meter sits: between the array and the storage, so it measures only the array’s output; or after both, but bi-directional and able to display a net value.
The installer’s declaration includes a schematic of the metering. That is much easier to obtain as a condition of the order than as a favour six months later — and if your installer cannot produce it, that tells you something about whether they have done this before.
Send the declarations to your FIT licensee — the supplier who pays you — not to Ofgem.
If you are on the Smart Export Guarantee
The SEG rule is stated plainly, and then qualified in a way that matters:
Generators are able to add battery storage to their installation that is receiving SEG payments as long as the export meter is still able to measure the amount of electricity generated/exported from the installation separately from any other source.
And where it cannot:
Where the export meter for an eligible installation also records, but cannot determine the amount of, electricity exported from another source (“Brown Export”), a SEG licensee is not obliged to make SEG payments.
Ofgem’s own advice, in the same paragraph, is to ask first: SEG generators should check with their licensee how it will view any intended changes to the co-located storage.
Arrangements Ofgem accepts. The guidance gives worked examples that satisfy the scheme, including inverter settings configured so the storage cannot import from the grid at all, and a disconnection relay that prevents the storage charging whenever there is import. Both work by making brown export impossible rather than by measuring it.
The awkward middle. Where the storage can charge from both sources and the green share would have to be calculated by deducting an import meter from an export meter, Ofgem says a licensee is not obliged to pay — while noting a licensee might accept the calculation and pay on that basis. That is discretion, and it is your supplier’s, so the answer is supplier-specific and worth getting in writing.
What this means when you are choosing a battery
Grid charging is a trade, not a free feature. A battery that can charge from a cheap overnight tariff is the single biggest improvement to storage economics we know of — see a battery without solar. It is also the thing that puts export payments in question. On a legacy FIT with a generous generation tariff, the FIT income can be worth far more than the tariff arbitrage; on a modern SEG installation with a 4p export rate, it usually is not.
Get the metering question answered in the quote. Where will the generation meter sit relative to the battery? Is it bi-directional? Which declarations will be needed? An installer who has done this before will answer in a sentence.
Tell your supplier before, not after. Both schemes are administered by your supplier. Everything above is easier as a question than as an appeal.
Sources
- Guidance for generators: Co-location of electricity storage and hydrogen production under the RO, FIT, REGO and SEG, version 6.2 Version 6.2, published 23 May 2025. Read in full. Chapter 3 and the scenarios in chapter 4 cover FIT; appendix 1 carries the declarations; appendix 3 covers the SEG.
- Smart Export Guarantee Annual Report — SEG Year 5
Contains public sector information licensed under the Open Government Licence v3.0.
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