Home battery safety and where a battery can go

A home battery stores a lot of energy in one box, so where it goes is not just a matter of looks. Australia has a standard for it, AS/NZS 5139:2019, and every battery supported by the federal Cheaper Home Batteries Program must be installed to it. Here is what that means for your home, in plain words, drawn from Solar Victoria's technical guidance for installers (reviewed by Energy Safe Victoria) and the federal program rules.

Battery chemistry: why LFP

Almost all home batteries sold today are lithium-ion, but there are two main types. Solar Victoria's buyers guide explains the difference:

• NMC (lithium nickel manganese cobalt oxide) packs more energy into a smaller size, but can overheat if discharged too quickly.
• LFP (lithium iron phosphate, sometimes written LiFePO4) is a little larger for the same capacity, but is considered the safer of the two.

That is why LFP has become the usual choice for batteries on the wall of a family home. Whatever the chemistry, ask your installer about its particular risks so the installation can deal with them, as Solar Victoria recommends.

Chemistry is only one part of it. The battery must also be on the Clean Energy Council's approved battery list to get the federal discount, which means it has been tested and certified against the relevant standards. It must be installed by, or with on site supervision from, a Solar Accreditation Australia installer with battery accreditation, with the wiring done by a licensed electrician.

Never in a habitable room

The firmest rule is that a battery cannot go in a habitable room of a home. A habitable room is one used for normal living, such as:

• bedrooms, including a spare bedroom
• living, lounge and family rooms
• the kitchen and dining room
• a study, playroom, sunroom or home theatre

Rooms like the bathroom and laundry are not habitable rooms. The guidance also says to think about what a room could become. A spare room used for storage today still counts as a bedroom if it could go back to being one.

Walls next to living areas

A battery mounted on, or close to, a wall with a habitable room on the other side needs that wall to be non-combustible. Brick, masonry block, concrete, compressed cement sheeting and ceramic or terracotta tiles qualify. Plasterboard and timber are not on that list, so the installer fits a non-combustible barrier, such as cement sheet, behind the battery that extends 600 mm past its sides. If the battery sits within 900 mm of the ceiling, the ceiling needs a barrier too. Glass and corrugated steel are not automatically treated as non-combustible, and any hole through the barrier into the living area larger than 5 mm has to be sealed with fire retardant material.

Places a battery cannot go

The standard also lists restricted locations. A battery must not be installed:

• within 600 mm to the side of, or 900 mm below, a doorway or other exit
• within 600 mm to the side of, or 900 mm below, a window or vent that serves a habitable room
• within 600 mm to the side of, or 900 mm below, a hot water unit, air conditioner or any other appliance that is not part of the battery system
• in a ceiling space or a wall cavity
• under stairs or under an access walkway
• on a roof, unless the roof has a permanent ladder or stairway for access
• in an escape route, with at least a metre of clear space around it so people can get past

The appliance zone also extends 600 mm out in front of the battery. In practice, the side of the house with the hot water unit, the air conditioner condenser and the back door is often the hardest place to fit one.

Garages

A garage is a common spot and can work well, but there are things to watch. The standard does not treat a garage as a dedicated battery room, because it is used for other things too. The battery may need protection from being hit by a car, and the guidance notes that a pillar or wall is not always enough on its own; it depends on where the battery sits. Keep the space around it clear, do not stack things on top of it, and keep flammable items and anything that conducts electricity away from it.

Outside walls, heat and weather

Solar Victoria notes that most home batteries can be installed outdoors. A few points make a big difference to how long it lasts:

• Shade. Batteries last longer at stable, cool temperatures. Avoid a wall in full afternoon sun if you can, and avoid uninsulated, unshaded metal sheds.
• Weather. Check the battery is rated for outdoor use where it will be mounted.
• Pests and kids. Any enclosure should be vermin proof and out of reach of children.
• Labels. The installation must carry the right safety signs, warnings and shutdown instructions.

What you can do

You do not need to learn the standard. You do need to know that your installer is applying it, so it is fair to ask where they plan to put the battery and why. Tell your home insurer about the battery too, and check how the policy treats it, as Solar Victoria suggests. If you are ever worried about an installation, raise it with the installer first, then the Clean Energy Regulator or Energy Safe Victoria.

When you are ready, design your system on your own roof then talk to us about where your battery would sit.