Panel installation and wiring

UK Plug-In Solar 800W Legal Limit Explained

From 27 August 2026, socket-connected plug-in solar became legal in the UK for the first time. The new rules set an 800W AC output cap and require kit certified against a government product specification. Here is what changed, what the rules actually cover, and where the limits still apply.

Helpful video. Kilowatts UK’s “Plug-In Solar: 800W Legal Limit Starting August 27” gives a clear overview of the legal change and what it means for UK homeowners.

1. What the 800W limit actually restricts

The 800W cap applies to the AC output of the micro-inverter, not the rated peak wattage of the solar panels. This is a practical distinction: a 1,000W or 1,200W panel will clip its output to 800W AC through a compliant micro-inverter, and that clipping is acceptable under the rules. You are not restricted to buying panels rated at 800W or less.

The limit also applies per-installation, not per-panel. A system with four 200W micro-inverters producing 800W AC in total is within scope. A system wiring two or more panels into a single inverter exceeding 800W AC output is not.

2. What BS 7671 Amendment 4 changed

Before Amendment 4 to the 18th Edition IET Wiring Regulations, any solar generation connected to a mains socket sat in a legal grey area. No standard explicitly addressed it, which meant network operators and building inspectors treated it as a permanent installation requiring Part P notification and a full Electrical Installation Certificate from a qualified electrician.

Amendment 4, published in April 2026 and tied to the August 27 legal date, reclassifies a compliant sub-800W AC unit as a portable appliance. That means it sits in the same regulatory category as a kettle or a phone charger when it comes to connection requirements. No dedicated spur, no Part P notification, and no Electrical Installation Certificate are needed for the socket-connected connection itself.

The RCD protection requirement remains: the socket circuit the unit plugs into must have RCD protection, which is standard on any modern consumer unit installed to 17th or 18th Edition wiring regulations. If your consumer unit predates that requirement, speak to a qualified electrician before connecting any plug-in solar device.

3. The Interim Product Specification: what certified kit must do

The government’s Department for Energy Security and Net Zero published the Interim Product Specification version 2.0 in July 2026. This document sets out exactly what a plug-in solar inverter must do to be sold legally as a compliant unit. The main requirements are:

• 800W AC maximum output, enforceable through the inverter’s own limits, not just a setting that can be changed by the user.
• Type-approved anti-islanding protection: the inverter must disconnect from the circuit within around 0.2 seconds if grid voltage drops or is lost. This protects electricity network workers from a small solar installation continuing to push current into a de-energised line.
• Single-phase connection only. Three-phase households fall outside the plug-in route at this stage.
• UKCA or CE marking under the relevant supply regulations, in addition to IPS certification.

As of August 2026, the specification has been published but no inverter has yet completed the IPS v2.0 certification process. The law is in force and the route is legal, but compliant certified products are still working through type-approval. Confirm IPS v2.0 certification with your supplier before buying.

4. When you still need an MCS installer

The 800W socket route is specifically narrow. It only removes the MCS and Part P requirements for the plug-in connection itself in the following circumstances. You still need a qualified MCS-certified installer if:

• You want Smart Export Guarantee (SEG) payments for electricity exported to the grid. SEG requires MCS certification of the installation.
• Your system connects via a hardwired permanent connection rather than a standard 13A socket, including a dedicated spur, a connection inside the consumer unit, or a DC string running to an inverter via cable trunking.
• You are adding battery storage that exports to the grid on a DNO-notifiable basis.
• Your planned output exceeds 800W AC from a single installation.

In those situations, the rules revert to the standard framework: G98 or G99 DNO notification, Part P building regulation compliance, and an MCS-certified installer for any equipment claimed under the SEG. DNO notification under G98 covers installs up to 16A per phase with no battery export; G99 covers everything larger or where battery export is included.

5. What changes in practice for DIY solar owners

For the DIY segment of the market, the August 2026 legal change is significant. Balcony solar systems, garden-panel setups, and flat-mounted arrays feeding a single outdoor socket have moved from legal uncertainty into a defined framework. You can connect a certified plug-in unit to a standard household socket without needing to notify your network operator or hire an electrician for the connection itself.

The main practical constraint right now is product availability. Until IPS v2.0-certified inverters reach the UK market, no kit is fully compliant with the new rules, even if it was marketed as a plug-in solar system beforehand. Check for the certification mark before purchase, and keep the documentation.

Once certified kit is available, the process is: buy a compliant system, confirm your socket circuit has RCD protection, follow the manufacturer’s installation instructions, and plug in. No notification, no certificate, no installer required for that step.

Frequently Asked Questions

Is plug-in solar legal in the UK now?

From 27 August 2026, yes. SI 2026 No. 848 came into force on that date and BS 7671 Amendment 4 reclassifies compliant units of 800W AC or less as portable appliances rather than notifiable installations. However, the kit must be certified against the DESNZ Interim Product Specification v2.0. As of August 2026, no inverter had yet completed that certification process, so check for IPS v2.0 certification before buying.

Do I need to tell my DNO about a plug-in solar system?

Not for the socket-connected plug-in route under 800W AC. DNO notification (G98 or G99) is required for permanently wired solar installations. A certified plug-in unit connecting via a standard 13A socket is treated as a portable appliance and does not trigger G98 or G99. If you later add battery storage that exports to the grid, the rules change and you should check with your DNO.

Can I get Smart Export Guarantee payments from a plug-in solar system?

No, not via the socket-connected plug-in route. The Smart Export Guarantee requires MCS-certified equipment and a registered MCS installation. Plug-in solar connecting through a standard socket is not eligible for SEG export tariff payments. If earning from export is your goal, a professionally installed MCS-certified rooftop system is the route to take.

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