Eliot Crook, Founder · Updated · 12 min read
Home Battery Rules and Regulations: What You Actually Need Permission For
Most UK homeowners will not need planning permission for a home battery, but planning is the smallest of the four approvals involved. What actually governs your installation is the application to your network operator, which depends entirely on your inverter size, where the battery is allowed to sit under fire-safety guidance, whether your installer is MCS certified, and, from 15 October 2026, a brand-new chapter of the wiring regulations written specifically for home batteries. Here is what each one means, and which are your installer's job rather than yours.
The four rules that actually apply
Battery installations get talked about as though planning permission is the hurdle. It rarely is. Four things actually govern your install, and only one of them can realistically stop it.
Planning permission is your responsibility, but only if your property is unusual. It rarely blocks anything, though a listed building genuinely can.
The DNO application, either G98 or G99, is normally handled by your installer, and it is the one with teeth. A G99 can be refused or come back with conditions.
Fire-safety siting under PAS 63100:2024 is your installer's job. It will not stop the install, but it can rule out the spot you had in mind.
The wiring regulations, BS 7671, are also your installer's job. They will not block anything either, but from 15 October 2026 they change what compliant means.
MCS certification is a fifth item that is optional in law but decides whether you can sell power back on the Smart Export Guarantee.
Planning permission: the honest answer
You will read on a lot of installer websites that domestic battery storage "is permitted development". Be careful with that. There is no dedicated permitted-development class for domestic battery storage in the way there is for solar panels, and the Planning Portal has no specific domestic battery page. In practice the overwhelming majority of home battery installations proceed without a planning application, because a wall-mounted or floor-standing unit inside a garage, utility room or on an external wall does not amount to development that needs consent. But "almost always fine" is not the same as "there is a rule that says yes".
There are four cases where you genuinely should check first.
Listed buildings. Listed building consent is a separate regime from planning permission and it can apply to internal work. Check before you commit.
Conservation areas, National Parks and Areas of Outstanding Natural Beauty, particularly for anything visible from the road.
Ground-mounted units or a new outbuilding built to house the battery. Once you are putting up a structure, normal outbuilding rules apply.
Flats and leasehold properties, where your lease and freeholder matter more than planning law.
The Planning Portal's own standing advice is to contact your local planning authority and discuss the proposal before work begins. For a typical house with an indoor or wall-mounted battery, that call takes five minutes and removes the only genuinely expensive risk on this list.
Your DNO application: G98 or G99
This is the approval that actually has teeth, and it is decided by one number: the rated output of your inverter, not the size of your battery in kWh. Your Distribution Network Operator, the company that owns the cables in your street rather than the company that bills you, needs to know about anything that can push power onto the network.
The threshold is 16 A per phase, which on a standard single-phase UK supply is 3.68 kW.
If a DNO limits your export, that affects what you can earn on the Smart Export Guarantee, not your ability to charge cheaply overnight. The savings modelled in our payback calculator come from buying at the off-peak rate rather than from exporting, so an export limit usually dents the earnings side rather than the core case.
A reputable installer submits this for you and should tell you which one applies before you pay a deposit. If a quote does not mention G98 or G99 anywhere, ask why. It is worth putting to every firm you speak to.
Worked example: Powerwall 3 vs a 3.6 kW hybrid
A Tesla Powerwall 3 is rated at 11.04 kW on a UK single-phase supply. That is roughly three times the 3.68 kW G98 threshold, so it needs a G99 application, submitted and approved before anyone fits it. A modest 3.6 kW hybrid inverter on the same house would slip under G98 and could be fitted first and notified afterwards. Same house, same tariff, completely different paperwork and a difference of several weeks in lead time.
Compare MCS-certified installersWhere the battery is allowed to go
PAS 63100:2024 is the British Standards specification covering protection against fire for battery storage in dwellings. It came into effect on 31 March 2024, it is not retrospective, and it is important to be precise about its status: it is a specification containing recommendations, not law. It is not directly referenced in MCS's battery installation standard either, though it is picked up indirectly through the IET Code of Practice, which says installers "should" follow it. In practice, a competent installer will follow it, and one who dismisses it is telling you something useful about themselves.
PAS 63100 rules out three locations outright.
Lofts, roof spaces and voids. This is the big one, and it surprises people who assumed the loft was the obvious home for a battery.
Rooms used for sleeping.
Escape routes, so not hallways, corridors or staircases you would use to get out.
If the battery has to go indoors, it asks for two things.
Fire separation from habitable rooms and escape routes, with walls, ceilings and floors rated to at least REI 30, meaning 30 minutes of fire resistance.
Fire detection in the battery's location, interlinked with the alarm system in the rest of the house.
The preferred locations are outdoors or in a detached garage or outbuilding, away from habitable rooms. An attached garage separated by a fire-rated wall, a utility or plant room with proper separation, or an external wall-mounted unit in a weatherproof enclosure are all commonly used. If you had a particular spot in mind, raise it at survey stage rather than on installation day.
What changes on 15 October 2026
The IET and BSI published Amendment 4 to BS 7671:2018, the wiring regulations, on 15 April 2026. The previous version, BS 7671:2018+A2:2022+A3:2024, is withdrawn six months later, on 15 October 2026, at which point A4:2026 is the version in force.
For home batteries this is not a footnote. Amendment 4 introduces a new chapter covering stationary secondary batteries, which is the formal name for the kind of fixed battery you are buying. It brings in requirements on system design, power conversion equipment, bidirectional and hybrid inverters, and whether protective devices are suitable for power flowing in two directions. It also covers battery location, ventilation and fire-risk mitigation, and it addresses vehicle-to-home and vehicle-to-grid setups.
If you are getting quotes now for an installation later in the year, ask which version of BS 7671 the design is being certified against. Work designed and certified after 15 October 2026 should be assessed against Amendment 4. This is your installer's responsibility rather than yours, but it is a fair question, and the answer tells you whether they are current.
MCS certification: what it does and does not do
MCS is a certification scheme for installers and products. Its battery installation standard, MIS 3012, covers systems up to 50 kW.
Two things worth being clear about, because both are routinely misstated:
MCS certification IS effectively required to claim the Smart Export Guarantee. Suppliers ask for an MCS certificate before they will pay you for exported power.
MCS certification is NOT a condition of the 0% VAT rate. These two get conflated constantly. The VAT relief attaches to the installation of qualifying energy-saving materials, not to the installer's membership of a scheme.
If you never intend to export, MCS is a quality signal rather than a requirement. If you want SEG payments, treat it as non-negotiable.
The VAT deadline running underneath all of this
Battery storage installed in a residential property currently carries 0% VAT. That relief runs until 31 March 2027, after which the rate reverts to 5%, not to the standard 20% rate. On a £7,000 installation the difference is roughly £350, so it is a real number but not the cliff edge it is sometimes presented as. The detail is in VAT Notice 708/6. We cover the timing and what it does to the maths in our guide to the 0% VAT deadline, linked below.
What to ask your installer
1. Is this a G98 or a G99, and have you submitted it?
2. If it is a G99, has the DNO responded, and did they apply an export limit?
3. Where exactly are you proposing to put the battery, and does that comply with PAS 63100?
4. Which version of BS 7671 will the certificate be issued against?
5. Are you MCS certified, and will I get an MCS certificate for the SEG?
6. Is the DNO paperwork in my name?
Run the payback numbers first so you know what a sensible fitted price looks like, then put these six questions to every installer you shortlist.
Sources
IET and BSI, Amendment 4 (2026) to BS 7671:2018, published 15 April 2026.
PAS 63100:2024, effective 31 March 2024.
MCS MIS 3012 Battery Installation Standard.
ENA Engineering Recommendations G98 and G99.
HMRC VAT Notice 708/6.
Planning Portal.
Last reviewed 20 July 2026.
At a glance
| G98 | G99 | |
|---|---|---|
| Applies to | Up to 16 A per phase (3.68 kW single-phase, 11.04 kW three-phase) | Above 16 A per phase |
| Timing | Fit and inform. Notify after commissioning, typically within 28 days | Apply and wait. Approval must be in place before installation |
| Typical wait | None. The DNO assesses afterwards | Typically 4 to 8 weeks |
| Can it be refused? | No, it is a notification | Yes, and it can come back with conditions or an export limit |
| Typical cost | Normally free | Free to several hundred pounds, occasionally more |
Frequently asked questions
Do I need planning permission for a home battery in the UK?
In most cases, no. A wall-mounted or floor-standing battery in a garage, utility room or on an external wall does not normally require a planning application. There is no dedicated permitted-development class for domestic battery storage though, so the position is "almost always fine" rather than "explicitly allowed". Check with your local planning authority first if your home is listed, in a conservation area, or if the battery needs a new outbuilding or a ground-mounted enclosure.
What is a DNO application and do I have to do it myself?
Your Distribution Network Operator owns the cables in your street, as distinct from the supplier who bills you. Because a battery can push power back onto the network, the DNO needs to know it exists. Your installer normally submits the application for you, but the paperwork should be in your name. Ask to see it.
What is the difference between G98 and G99?
It is decided by inverter output, not battery capacity. Up to 16 A per phase, which is 3.68 kW on a single-phase supply, you are under G98: the system can be fitted and then notified, typically within 28 days. Above that threshold you need a G99 application, which must be approved before installation and typically takes four to eight weeks.
Can my network operator refuse my battery installation?
A G98 notification cannot be refused because it is a notification rather than a request. A G99 application can be refused, and more commonly it is approved with conditions such as an export limit. An export limit affects what you can earn from selling power back, not your ability to charge the battery cheaply overnight.
Can I put a home battery in my loft?
PAS 63100:2024 advises against installing batteries in lofts, roof spaces and voids. It is guidance rather than law, but it reflects how a battery fire behaves and where it would be hardest to fight. Most competent installers will decline to fit one there. Outdoors, a detached garage or outbuilding, or a properly separated utility room are the usual alternatives.
Is PAS 63100 a legal requirement?
No. It is a publicly available specification containing recommendations, it came into effect on 31 March 2024, and it does not apply retrospectively to earlier installations. It is not directly referenced in MCS's MIS 3012 battery standard, although it is picked up indirectly via the IET Code of Practice. Treat an installer's attitude to it as a competence signal.
What changes on 15 October 2026?
Amendment 4 to BS 7671:2018 was published on 15 April 2026, and the previous version is withdrawn on 15 October 2026, making A4:2026 the version in force. It adds a new chapter on stationary secondary batteries covering system design, bidirectional and hybrid inverters, protective devices for two-way power flow, battery location, ventilation and fire-risk mitigation. If your installation lands after that date, ask which version your certificate is issued against.
Do I need an MCS certified installer to get 0% VAT?
No. MCS certification is not a condition of the 0% VAT rate on battery storage, despite how often the two are linked. MCS does matter if you want to claim the Smart Export Guarantee, because suppliers require an MCS certificate before paying for exported electricity. The 0% rate runs until 31 March 2027 and then reverts to 5%.
Related
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