Adding a battery to solar panels you already have
Most UK homes with solar export a share of what they generate. A battery keeps some of that for the evening. Three things decide what a retrofit changes for you: the inverter you already have, the export payments you get now, and the installed price. The rules below are the ones an installer should confirm in writing.
Start with what is on your roof and in your loft
- Your inverter. Note its make, model and age (it is on the label). An AC-coupled battery has its own inverter and connects next to the existing one. A DC-coupled battery shares a hybrid inverter with the panels, which usually means replacing yours. An inverter near the end of its life makes a hybrid replacement easier to justify.
- Your export payments. Find your current export rate on your statement. Every kWh of solar the battery keeps is a kWh you no longer get that rate for; the higher it is, the less the battery adds. Compare export rates, because some suppliers pay more only if they installed the battery.
- Your quote. Put the installed price, your yearly use and your solar figure into the calculator before you decide on size.
VAT
HMRC states that the reduced VAT rate of 5% applies from 1 April 2027 onwards. Valid from 1 April 2027.
“From 1 April 2027 onwards these will revert to the reduced rate of VAT of 5%.”Source: gov.uk, read 19 October 2026
HMRC includes retrofitting a battery to store electricity generated by qualifying energy-saving materials.
“the retrofitting of a battery for storing electricity generated by one or more qualifying energy-saving materials (solar panels, wind turbines and water turbines);”Source: gov.uk, read 19 October 2026
HMRC includes installing a standalone battery to store grid electricity.
“the installation of a standalone battery for storing electricity from the grid (the mains electricity);”Source: gov.uk, read 19 October 2026
Supplying energy-saving materials without installing them is standard-rated.
“However, if you supply energy-saving materials without installing them your supply will be standard-rated.”Source: gov.uk, read 19 October 2026
HMRC’s notice covers Northern Ireland too: guidance on the time-limited zero rate for homes there, with effect from 1 May 2023, was added to it.
“Guidance on the time-limited zero rate of VAT for installations of energy-saving materials installed in residential accommodation in Northern Ireland, with effect from 1 May 2023, has been added.”Source: gov.uk, read 22 October 2026
HMRC states that the zero rate for specified energy-saving materials runs from 1 May 2023 to 31 March 2027.
“A zero rate applies to the installation of certain specified energy-saving materials from 1 May 2023 to 31 March 2027.”Source: gov.uk, read 22 October 2026
Export payments after you add a battery
Ofgem states that adding battery storage is possible where the export meter separately measures electricity from the eligible installation.
“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.”Source: ofgem.gov.uk (PDF, page 64), read 19 October 2026
SEG licensees must pay for stored electricity subsequently exported where it is guaranteed to come only from the SEG installation.
“SEG Licensees are obligated to make SEG payments when the electricity stored in co-located storage and subsequently exported can be guaranteed to only have come from the SEG installation (green export).”Source: ofgem.gov.uk (PDF, page 64), read 19 October 2026
Ofgem says that if your export meter also records electricity from another source, such as grid power stored in a battery, and cannot tell how much, the supplier does not have to make SEG payments.
“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.”Source: ofgem.gov.uk (PDF), read 22 October 2026
Ofgem states that SEG payments are calculated from export meter readings.
“SEG payments are calculated by using export meter readings.”Source: ofgem.gov.uk, read 22 October 2026
Telling your network operator
The ENA guide gives the single-phase equivalent as 16 A per phase and 3.68 kW.
“16 A per phase corresponds to 3.68 kW”Source: ssen.co.uk (PDF, page 24), read 19 October 2026
The guide explicitly includes electricity storage devices.
“this includes electricity storage devices”Source: ssen.co.uk (PDF, page 24), read 19 October 2026
For the described microgenerator notification route, the installer must notify the DNO within 28 days.
“Your installer must notify the DNO within 28 days”Source: ssen.co.uk (PDF, page 44), read 19 October 2026
The ENA guide says the 16 A limit counts all generation in one home together: 3.68 kW on a single-phase supply and 11.04 kW on a three-phase supply.
“16 A per phase corresponds to 3.68 kW on a single-phase supply and 11.04 kW on a three-phase supply and refers to the aggregate micro-generator capacity installed in a single premises”Source: ssen.co.uk (PDF), read 22 October 2026
The ENA guide says a battery used together with solar panels is likely to take the total above 16 A per phase, so EREC G99 applies.
“electricity storage devices in conjunction with PV (or other technologies) to offset consumption, the total connected generation is likely to be above 16A / phase and hence EREC G99 applies”Source: ssen.co.uk (PDF), read 22 October 2026
The ENA guide says network operators run a fast-track application for some home-scale batteries, last revised in November 2022.
“DNOs have implemented a fast-track application process (last revised November 2022), for some domestic scale electricity storage”Source: ssen.co.uk (PDF), read 22 October 2026
The ENA guide quoted here is dated March 2024. What counts for your home is your own network operator’s current process, so ask your installer which route (notify after, or apply before) your system needs, and to put it in writing.
Installer certification
SEG requires installation and installer certification through MCS or an accredited equivalent.
“certified through the microgeneration certification scheme (MCS) or a scheme accredited as equivalent”Source: gov.uk, read 19 October 2026
SEG requires a meter capable of half-hourly export readings.
“meter capable of providing half-hourly export readings”Source: gov.uk, read 19 October 2026
MCS publishes a battery installation standard.
“MIS 3012: 2025 ISSUE 1.0”Source: mcscertified.com (PDF, page 1), read 19 October 2026
Compliance with the battery standard is mandatory for contractors certified to the stated MCS framework.
“Compliance with this Standard is mandatory for MCS Contractors certified to MCS: 2025.”Source: mcscertified.com (PDF, page 6), read 19 October 2026
Check the installer on the MCS register before you sign; see choosing an installer.
Planning permission
For the battery itself:
The government battery guide says home batteries generally do not require planning permission, while advising a local council check.
“Planning permission is not generally required for home batteries but you should double check with your local council’s planning office.”Source: cleanenergy.campaign.gov.uk, read 19 October 2026
Only if you also add or move panels: the solar rules per nation
Planning Portal states that residential solar installations may be permitted development.
“may be 'permitted development' with no need to apply to the local authority for planning permission.”Source: planningportal.co.uk, read 19 October 2026
Welsh guidance says listed buildings require planning permission and may also require listed building consent.
“If your property is a listed building installation will require planning permission and is likely to require an application for listed building consent.”Source: gov.wales, read 19 October 2026
Scottish guidance permits conservation-area installations on a rear elevation, subject to its further restrictions.
“In a conservation area, development is permitted provided the solar panels and equipment are mounted on a rear elevation”Source: gov.scot, read 19 October 2026
Northern Ireland guidance highlights conservation areas and listed buildings as cases where permission may be needed.
“You may have to get planning permission to fit a PV system, especially in conservation areas or on listed buildings.”Source: nidirect.gov.uk, read 19 October 2026
Scottish dwelling solar permitted development excludes listed buildings and their curtilage.
“Development is not permitted on a listed building or within the curtilage of a listed building.”Source: gov.scot, read 20 October 2026
The Scottish dwelling solar class also excludes World Heritage Sites.
“(ii) within a World Heritage Site.”Source: gov.scot, read 20 October 2026
England: the dwellinghouse wall projection limit differs when the wall adjoins a highway.
“where the wall abuts on a highway, the solar PV or solar thermal equipment protruding more than 0.2 metres beyond the plane of the wall”Source: legislation.gov.uk, read 22 October 2026
England: the other dwellinghouse wall case has a separate projection limit.
“in any other case, the solar PV or solar thermal equipment protruding more than 0.4 metres beyond the plane of the wall”Source: legislation.gov.uk, read 22 October 2026
England: the dwellinghouse pitched-roof projection exclusion is stated separately.
“the solar PV or solar thermal equipment protruding more than 0.2 metres beyond the roof slope”Source: legislation.gov.uk, read 22 October 2026
England: listed dwellinghouses and their curtilage buildings are excluded from this permitted-development class.
“the solar PV or solar thermal equipment would be installed on a dwellinghouse, or on a building within the curtilage of a dwellinghouse, if the dwellinghouse is a listed building”Source: legislation.gov.uk, read 22 October 2026
England: the protected-area exclusion covers a highway-facing wall or enclosure.
“in the case of land within a conservation area or which is a World Heritage Site, the solar PV or solar thermal equipment would be installed on a wall, balcony or roof enclosure which fronts a highway”Source: legislation.gov.uk, read 22 October 2026
Scotland: the dwelling solar-equipment projection restriction is stated in the guidance.
“No part of the solar panel equipment may protrude more than 1m from the surface of the wall, roof plane, roof ridge or chimney.”Source: gov.scot, read 22 October 2026
Scotland: conservation-area siting is restricted to the stated elevations.
“In a conservation area, development is permitted provided the solar panels and equipment are mounted on a rear elevation or a side elevation if that side elevation does not front a road.”Source: gov.scot, read 22 October 2026
Scotland: redundant solar equipment must be removed.
“Where the solar panel equipment is no longer needed or is incapable of generating heat or electricity, as the case may be, it must be removed as soon as is reasonably practical.”Source: gov.scot, read 22 October 2026
Wales: visible panels on the principal or side elevation walls in protected areas require consent.
“If your property is in a conservation area, or in a World Heritage Site planning consent is required when panels are to be fitted on the principal or side elevation walls and they are visible from the highway.”Source: gov.wales, read 22 October 2026
nidirect, the Northern Ireland government site, tells you to check with your divisional planning office before a solar system is installed.
“Always check with your divisional planning office about planning issues before you have a system installed.”Source: nidirect.gov.uk, read 22 October 2026
Will it pay back?
Use the calculator with your generation, use and export rate.