Where Can a Home Battery Be Installed? PAS 63100 Explained

Outside, where that is practicable. If a battery has to go indoors, it needs a location with fire-resisting separation from the rest of the house, and some places are ruled out altogether: bedrooms, lofts and roof spaces, and escape routes that aren’t protected.

Those rules come from PAS 63100:2024, a fire-safety specification for battery storage in homes. It was published by the British Standards Institution, sponsored by the Department for Energy Security and Net Zero, and came into effect on 31 March 2024. Here is what it says, and what it usually means for a London home.

Key points

• Outdoors is the first choice where practicable, for example on an outside wall or in a detached garage.

• Never in a bedroom, the loft or another roof space or void, or on an escape route that isn’t protected.

• Indoors, the battery needs a location separated from the rest of the house by construction rated to resist fire for at least 30 minutes.

• A battery in a rarely visited spot, such as a store cupboard, needs a smoke alarm there, linked to the alarms in the rest of the house.

• There is a limit on the total battery energy stored in one home, with a higher limit for outdoor and separated garage locations.

• Every home is different, so the final location is decided at the survey.

What PAS 63100 is

PAS stands for Publicly Available Specification. PAS 63100 sets out how to install battery storage in a home so that the risk from fire is properly controlled. It covers the battery itself, its management system, the inverter or other power conversion equipment, and where all of it goes.

It sits alongside the wiring regulations, BS 7671, rather than replacing them. The installer completes a statement confirming the installation conforms to PAS 63100, and that statement is attached to the electrical installation certificate for the work.

It doesn’t cover every home. It excludes, for example, homes with more than 200 m² of floor area and high-risk residential buildings, where other fire-safety rules and specialist advice apply.

The first choice: outdoors

PAS 63100 says that, where practicable, storage batteries shall be installed outdoors. For most London houses that means one of:

• an outside wall, often down a side return or at the back of the house

• a detached garage or outbuilding

• a suitable weatherproof enclosure, where the battery itself isn’t rated for outdoor use

Outdoors still has rules. The battery shouldn’t sit where it could block a way out of the house, and the standard sets out where units and their ventilation can go in relation to doors, windows and openings. Where a battery could be hit by a car, for example in a garage or beside a driveway, it needs protecting from impact.

The places that are ruled out

PAS 63100 lists locations where a battery must not go. The ones that matter most in a house are:

• rooms where people sleep

• escape routes that aren’t protected, such as the hallway, landing and stairs you would use to get out in a fire

• voids, roof spaces and lofts

The thinking is simple. A fire in a bedroom or on your way out puts people at risk before they know about it, and a fire in a loft can take hold unseen and is hard to reach.

If you already have a battery in a loft or on a landing, that doesn’t automatically mean it is unsafe, but it is worth having the installation looked at.

Installing indoors

If outdoors isn’t practicable, a battery can go inside, but the location needs fire-resisting separation from the rest of the home: walls, ceiling and door built to resist fire for at least 30 minutes.

In practice that tends to point to a utility room, a separate plant room or an integral garage built to the right standard, rather than a kitchen, living room or the cupboard under the stairs. An under-stairs cupboard is often on the escape route itself, which usually rules it out or needs careful assessment.

Two more indoor requirements:

• Fire detection. If the battery is somewhere people rarely go, such as a store cupboard, there must be a smoke alarm or multi-sensor fire alarm in that location, interlinked with the fire alarms in the rest of the home.

• Ventilation. The location needs adequate ventilation, so the battery doesn’t overheat when it charges.

How much battery a home can have

PAS 63100 also limits the total battery energy stored in one home. In most cases the limit is 40 kWh. For certain outdoor, detached or fire-separated garage locations it rises to 80 kWh.

For most homes that is far more than they need. Our guide to what size battery you need explains how to size one properly.

What the MCS battery standard adds

Installers certified by MCS must also follow the MCS battery installation standard, MIS 3012. It requires batteries to be located so that a fire in the battery doesn’t compromise protected escape routes, asks for enclosures and rooms to be ventilated, and recommends fire detection where a battery is in a rarely visited part of the property.

What this means for a typical London home

London housing makes this interesting. Terraces often have no side access, flats have shared escape routes, and lofts, which used to be a popular spot, are now ruled out.

Some common situations:

• Terraced house with a garden. An outside wall at the back is often the answer, if the cable route to the inverter and consumer unit works.

• House with a garage. A detached garage is a strong option. An integral garage can work if it has the right fire separation and impact protection.

• No outside space. It may be possible to create a suitable location indoors, but it needs the fire-resisting construction, detection and ventilation described above, and sometimes the honest answer is that a battery isn’t practical.

• Flats. Shared escape routes and building rules make flats more complicated, and the building owner or managing agent usually needs to be involved.

Every one of these is a site-specific judgement. The location is decided at the survey, once we have seen the property, and we will tell you if we can’t find somewhere suitable.

Our guides to adding a battery to existing solar panels and what keeps working in a power cut cover the other big questions people ask before buying.

Frequently asked questions

Can a solar battery go in the loft?

No. PAS 63100 rules out voids, roof spaces and lofts.

Can a battery go in my garage?

Often, yes. A detached garage is one of the better locations. An integral garage needs fire-resisting separation from the house, and the battery needs protecting from being hit by a car.

Can a battery be installed outside?

Yes, and where practicable that is the preferred location. The battery needs to be rated for outdoor use or housed in a suitable enclosure, and positioned away from doors, windows and the way out of the house.

Does PAS 63100 apply to batteries installed before March 2024?

It came into effect on 31 March 2024 and sets out how batteries should be installed now. If an older installation is in a location it rules out, have it checked.

Will you tell me if there’s nowhere suitable?

Yes. We would rather tell you a battery doesn’t work in your home than install one in the wrong place.

Request a solar and battery quotation. We’ll survey the property and find a location that meets the standard, or tell you honestly if there isn’t one.