BS 7671 Amendment 4: What the October 2026 Changes Mean for Solar & Battery Storage
If you have a home battery, are thinking about installing one, or work with solar and battery storage, there’s an important date coming up: 15 October 2026. This date is significant because it relates to the latest BS7671 Amendment, which will affect installation requirements in the industry.
New electrical regulations are changing the way battery storage systems are considered within UK electrical installations, with a greater focus on battery safety, location and how modern renewable technologies work together.
Here’s what’s changing – and what it actually means.
What is changing on 15 October 2026?
In April 2026, a new version of the UK Wiring Regulations was published: BS 7671:2018+A4:2026, also known as Amendment 4.
The electrical industry was given six months to transition to the new regulations.
That transition ends on 15 October 2026, when Amendment 4 becomes the current version of BS 7671 and the previous version is withdrawn.
One of the biggest changes is particularly relevant to the growing number of UK homes and buildings using solar panels and battery storage.
Why are the regulations changing?
The way we use electricity is changing.
Traditionally, electricity entered a property from the grid and was distributed around the building.
Today, a home might have:
- Solar panels generating electricity
- A battery storing and supplying energy
- An EV charger
- A heat pump
- A backup power supply
- Electricity coming from the grid
This means electricity doesn’t always travel in one direction anymore.
Modern electrical systems need to safely manage energy coming from several different sources – and the regulations are evolving to reflect that.
What does Amendment 4 mean for battery storage?
Amendment 4 introduces a new section of the Wiring Regulations specifically covering stationary batteries: Chapter 57 – Stationary Secondary Batteries.
Put simply, battery storage now has its own dedicated requirements within BS 7671.
These cover important areas such as:
Where the battery is installed
The location of a battery needs to be properly considered as part of the overall system design.
How the system is protected
The correct protective devices, electrical equipment and earthing arrangements need to be considered.
Heat and fire risk
Installations need to take account of thermal effects and other potential hazards.
How the battery interacts with the rest of the property
A battery isn’t simply another electrical appliance. It can both receive and supply electricity, so the whole electrical system needs to be considered.
Do home batteries now have to be installed outside?
No – and this is an important distinction.
Amendment 4 does not say that every home battery must be installed outdoors.
The correct location depends on the individual property, the equipment being installed, the manufacturer’s requirements and the relevant safety considerations.
However, Amendment 4 does strengthen the relationship between the Wiring Regulations and PAS 63100, which provides guidance around the safe installation of battery energy storage systems in homes.
This means factors such as battery location, ventilation, surrounding conditions and fire-risk mitigation are increasingly important when deciding where a battery should go.
For some properties, a purpose-designed external battery and inverter enclosure can therefore provide a practical way of locating equipment outside the home when an internal location isn’t suitable or desirable.
This is one of the reasons Eco-ESS developed our range of purpose-designed external battery and inverter enclosures.
What if I already have a battery installed?
If you already have a battery storage system, the new regulations do not automatically mean you need to move it or replace it after 15 October.
BS 7671 is not generally retrospective.
An installation that was correctly designed and installed to the requirements that applied at the time does not automatically become unsafe simply because the regulations have since changed.
However, if you’re making additions or alterations to your electrical system, the requirements applicable to that new work will need to be considered.
Why does this matter for solar too?
Solar panels and batteries are increasingly being installed as part of one wider home-energy system.
For example, one property might simultaneously have electricity:
coming from the grid → being generated by solar → being stored in a battery → being supplied back from the battery.
Amendment 4 recognises this.
Under the relevant new requirements, stationary batteries are considered as a generating source rather than simply a load.
For installers, that means protective devices, switchgear and distribution equipment need to be selected with these different directions of energy flow in mind.
What should installers be doing before October?
If you install solar PV or battery-storage systems, now is the time to familiarise yourself with Amendment 4 rather than waiting until the transition period ends.
Particular attention should be given to:
- The new Chapter 57 battery requirements
- PAS 63100
- Where batteries are located
- Protective devices
- Bidirectional energy flow
- Earthing
- Heat and fire-risk considerations
- Manufacturer installation requirements
- Distribution systems containing multiple energy sources
The biggest shift is in how the system is viewed.
A battery should no longer be considered in isolation.
Solar, battery storage, EV charging, heat pumps, backup supplies and the grid can all form part of one connected energy system – and the electrical installation needs to be designed accordingly.
The key date: 15 October 2026
Amendment 4 reflects how quickly the way we generate, store and use electricity is changing.
For homeowners, it means battery installations are being considered within a clearer framework focused on safe integration into the wider electrical system.
For installers, it means understanding how battery storage, solar PV and other energy technologies interact is becoming increasingly important.
The transition ends on 15 October 2026.
At Eco-ESS, we’re developing infrastructure specifically for this new generation of energy systems – from external battery and inverter enclosures to whole-home backup, automatic transfer solutions, pre-assembled DC protection and renewable-energy distribution systems.
Safer. Smarter. Ready for modern energy.
Frequently Asked Questions
Do batteries have to be installed outside after October 2026?
No. There is no blanket requirement saying all domestic batteries must be installed outdoors. The appropriate location depends on the property, equipment, manufacturer’s requirements and relevant safety considerations.
Will I need to move my existing home battery?
Not automatically. Existing installations don’t suddenly become non-compliant simply because Amendment 4 becomes the current version of BS 7671.
What is PAS 63100?
PAS 63100 relates to the safe installation of battery energy storage systems in homes. Amendment 4 directly references PAS 63100 when addressing stationary batteries in dwellings.
Does Amendment 4 affect solar panels?
It can, particularly where solar forms part of a larger system incorporating battery storage, hybrid inverters, backup supplies or other sources of electricity.
What is Chapter 57?
Chapter 57 is the new section of BS 7671 dedicated specifically to stationary secondary batteries. It covers areas including battery installation, system design, electrical protection, earthing and thermal effects.
When does Amendment 4 take effect?
BS 7671:2018+A4:2026 was published on 15 April 2026. The six-month transition period ends on 15 October 2026, when the previous version is withdrawn.
I’m considering installing solar or battery storage. What should I do?
Speak to a competent installer who understands the latest requirements and can assess your property, proposed equipment and wider electrical system before recommending an installation.
Eco-ESS – engineered infrastructure for modern energy systems.
We develop solutions designed for today’s solar PV and battery-storage installations, including external battery and inverter enclosures, whole-home backup and automatic transfer solutions, pre-assembled DC protection and renewable-energy distribution systems.
