The short version
BS 7671 is the UK wiring regulations — the rulebook electricians follow. Amendment 4 is the 2026 update that, among other things, adds provisions covering small-scale plug-in solar. It was published on 15 April 2026, with a transition period ending 2 October 2026. After that date, all new electrical installation work in the UK must follow Amendment 4.
For plug-in solar specifically, Amendment 4 clears up the long-standing grey area around connecting a small PV source to a domestic socket — provided the kit meets specific safety conditions. Those conditions are what the forthcoming BSI product standard (expected summer 2026) will define in detail.
Plain take: Amendment 4 doesn't say "plug-in solar is allowed" in those words — it updates the general rules in a way that makes it possible, then hands off to a product standard to define exactly what's compliant.
What is BS 7671?
BS 7671 is the Requirements for Electrical Installations — the British Standard that covers fixed electrical work in buildings. It's published jointly by the Institution of Engineering and Technology (IET) and the British Standards Institution (BSI), and it's the document every UK electrician certifies work against.
The current edition is the 18th Edition (BS 7671:2018), with three prior amendments (1, 2, and 3) already incorporated. Amendment 4 is the latest revision — published in April 2026.
What actually changed in Amendment 4?
Amendment 4 is a substantial update — hundreds of pages — covering everything from EV charging to earthing to the rules for domestic battery storage. The parts that matter for plug-in solar are concentrated in a few specific sections:
- Chapter 712 (solar PV installations) — updated to recognise small-scale PV sources that don't require a dedicated spur or an MCS-certified installer, provided they meet the forthcoming BSI product standard.
- Chapter 722 (EV charging) — updated for bidirectional charging and V2H scenarios. Tangentially relevant because some plug-in battery systems share hardware design with V2H.
- Chapter 411 (protection against electric shock) — clarified RCD requirements that apply to a circuit containing a plug-in generator.
- Anti-islanding guidance — explicit requirement that any small-scale generator connected to a domestic socket must disconnect automatically if the mains supply fails (this was already industry practice but is now formally required).
What this means for a plug-in solar kit
The practical implication for anyone buying a plug-in kit is a checklist of things the kit itself must do to be compliant:
- Have a microinverter certified to EN 50549 (or an equivalent UK standard the BSI publishes this summer). EN 50549 is the European standard for small generators connecting to LV distribution networks — it covers anti-islanding, voltage and frequency tolerances, and grid protection.
- Disconnect automatically if the grid goes down — this is the anti-islanding requirement. It's a safety feature that stops the system back-feeding a de-energised network (which could electrocute an engineer working on the line).
- Stay within the power limit — the current expectation is 800W AC output per domestic plug-in circuit. That's the line beyond which a dedicated installation (and an electrician) becomes required.
- Use a plug rated for the UK — specifically BS 1363 (the standard 3-pin plug). Not a Schuko, not a Europlug, not a generic IEC lead. This is one of the specific things the BSI product standard is expected to nail down.
The grey zone: Amendment 4 updates the wiring rules, but the BSI product standard (expected July 2026) is what formally defines what counts as a compliant plug-in kit. Until that standard publishes, any kit sold as "Amendment-4-compliant" is technically claiming compliance with provisions that haven't fully crystallised yet.
Do I need an electrician to install a plug-in kit?
For a compliant plug-in kit: no. That's the whole point — it plugs into a standard socket, like any other appliance. Amendment 4 is specifically designed so that a kit meeting the product standard can be installed by the homeowner without an electrician, without notifying Building Control, and without falling under Part P of the Building Regulations.
If you want to modify the circuit — add a dedicated spur, fit a new RCD, or hard-wire a battery — you're back into the territory where Part P applies and notifiable work rules kick in. That's a job for a Competent Person Scheme registered electrician.
Do I need to tell my DNO (Distribution Network Operator)?
Under the existing G98 Fast Track notification process, generation up to 16A per phase (roughly 3.68 kW on a standard UK single-phase connection) is notifiable after installation, not before. For a plug-in kit at 800W, this means:
- You install the kit (no permission needed in advance).
- The manufacturer or installer submits a G98 notification to your DNO within 28 days.
- Your DNO records your property as having a small generator on the network.
Most reputable plug-in kits handle the G98 notification for you — it's part of the purchase flow. Check before you buy: a kit that doesn't offer G98 notification is a kit you'll have to self-notify via your DNO's website.
What Amendment 4 does not change
- Feed-in tariffs — the old FIT scheme is closed to new entrants. Amendment 4 doesn't bring it back. Export payments for plug-in kits remain a tariff-by-tariff question (Octopus and others pay for exported energy, but rates are modest).
- Rooftop solar rules — if you're installing a 4kW grid-tied rooftop system, you still need an MCS-certified installer and it's still governed by the pre-existing sections of Chapter 712. Amendment 4 adds to those rules; it doesn't replace them.
- Building insurance — your insurer may still want to know about a plug-in system even if no electrician was involved. Always check your policy.
Timeline
- 15 April 2026 — Amendment 4 published.
- April – October 2026 — Transition period. Electrical work done during this window can be certified against either Amendment 3 or Amendment 4.
- July 2026 (est.) — BSI product standard for plug-in kits expected.
- 2 October 2026 — Transition ends. All new work must comply with Amendment 4.
For a fuller timeline of UK plug-in solar milestones, see our UK plug-in solar timeline.
FAQ
Is my existing rooftop solar affected by Amendment 4?
If your system was installed under the rules that applied at the time, no — you don't have to retrofit anything. Amendment 4 applies to new installations from 2 October 2026. Existing certified installations continue to comply.
What's the difference between BS 7671 and the Building Regulations?
The Building Regulations are law. BS 7671 is a British Standard — not itself law, but compliance with it is the recognised way to satisfy Part P of the Building Regulations (which is law). So following BS 7671 is how electricians demonstrate they've met the legal requirement for safe electrical work.
Does Amendment 4 change the RCD type I need?
For a plug-in solar kit on an existing domestic ring main, the RCD that protects that circuit is the one you already have. Amendment 4 clarifies that a Type A RCD (the type found in most modern consumer units) is compatible with a plug-in kit — but older installations with Type AC RCDs may need upgrading for full compliance. If your consumer unit is pre-2015, worth a check.
Can I install a plug-in kit in a rented property?
Amendment 4 doesn't override your tenancy agreement. If your tenancy requires you to ask before making changes, you still need to ask. The regulation simply means that, if your landlord agrees, you don't need an electrician to plug in a compliant kit.
Where can I read Amendment 4 myself?
BS 7671:2018+A4:2026 is published by the IET and BSI and is a priced document — the full text isn't free. Your local library may have a reference copy, or the IET Electrical site has summaries and commentary aimed at electricians.