Adding a battery on a Feed-in Tariff: what happens to deemed export payments?

A battery can help you use more of your solar electricity at home. If you receive Feed-in Tariff payments, check how your export is paid before choosing a system.

The key question is whether your export payments are estimated or measured. That distinction matters when comparing a battery quote with the arrangement you already have.

What does deemed export mean?

Deemed export is an estimate of the electricity you send to the grid. The payment uses a set percentage of your generation meter reading, rather than a reading of actual exports. Metered export uses the electricity recorded as leaving your home.

Ofgem explains that eligible installations of 30 kW or less may receive deemed export payments where no export meter is fitted. The deemed percentage is set through government annual determinations. Read Ofgem’s explanation of deemed export.

Separate generation payments from export payments

Your generation payment relates to eligible electricity produced by your solar installation. Export is a separate part of the arrangement. Treating them as one figure can make a battery proposal difficult to assess.

Put your latest FiT statement next to your electricity bill. Mark the generation payment, the export payment and the cost of electricity bought from the grid. Ask for any unfamiliar entries to be explained before comparing a new proposal.

Does adding a battery automatically end deemed export?

Do not assume either that it ends deemed export or that all payments will stay unchanged. Ofgem requires eligible generation, and export where metered, to remain accurately measurable separately from other electricity. It also says your FiT provider must be notified when battery storage is connected.

Ask your installer for a simple before-and-after description of the panels, inverter, battery and meters. Send that description to the company handling your FiT payments and ask them to confirm the payment and metering implications in writing.

What if a smart meter is fitted?

This is a separate check, even if the battery installation leaves your solar panels in place. Ofgem’s generator guidance says that after smart-meter installation, generation payments are unaffected but deemed export payments stop and export is paid on a metered basis. Read Ofgem’s smart-meter and battery guidance.

Tell your FiT provider about any planned meter change. Ask which readings they will use, when the change takes effect and whether they need anything from you or the installer.

Compare the complete household picture

Ask the person preparing your quote to state which export arrangement their estimate assumes. A calculation based on deemed export is not an explanation of what happens if your account moves to metered export.

Keep these questions with the quote:

• How am I paid for export today?

• Which equipment or meters would change?

• What has my FiT provider confirmed about the proposed arrangement?

• Does the estimate show electricity purchases and export income separately?

If an answer changes during the survey, ask for the proposal to be updated before agreeing to the work.

Start with your current installation

Our Feed-in Tariff battery-storage page explains where to start. For the wider installation checklist, read five questions to ask before adding a battery on a FiT.

When you enquire, have your latest FiT statement and inverter details ready. We can use those to help frame the assessment and identify the questions that need answering for your home.