How plug-in solar panels work in the UK

Panels, inverter, plug and mounting

A compliant plug-in solar product includes panels, a grid-following inverter, a connection lead with a BS 1363 plug, and a panel mounting system. DESNZ’s Interim Product Specification requires at least one solar PV module. The inverter is the grid-facing part of the system; the specification calls it a grid-following inverter rather than requiring the term microinverter.

The standard UK 3-pin plug is part of an approved product, not a blanket permission to connect generating equipment to a socket. SI 2026/848, in effect since 27 August 2026, creates a route for a notified body to approve plugs for these products. DESNZ says only devices compliant with the Interim Product Specification can be sold in the UK and plugged in under the amended rules.

Check the product’s declaration of compliance and its entry on the Energy Networks Association G98 Type Test Register. The register includes entries marked non-compliant as well as compliant, so appearing on it is not enough. The UK rules page explains the framework, including the different territorial scope of the plug rules and installation rules.

Power feeds your home alongside the grid

Plug-in solar supplies your home’s electrical installation while operating in parallel with the electricity network. Some generated electricity can be used at home, while exported electricity goes back to the grid. Generation and household use are different quantities, so you should not count every generated kWh as a saving at your electricity unit rate.

The legal 800 W limit is the device’s maximum rated AC output, not the panels’ DC wattage. The Interim Product Specification separately sets a maximum apparent power of 800 VA. These are output limits, not a promise that the system will deliver that power throughout the day or a measure of annual energy production.

For a south-facing vertical 800 W kit in London, the calculator gives 596 kWh in a typical year, with 374 kWh used at home under its 164 W base-load assumption. It gives £99 a year in savings at the price cap rate, with exports paid 0. Use the calculator to compare your location and panel position rather than treating this example as your forecast.

The device shuts off without the grid

Plug-in solar is not a backup supply during a power cut. DESNZ says the devices are expected to have anti-islanding protection that forces them to shut off when they do not detect a connection to the wider electricity grid. Sunlight alone therefore does not mean the device will keep supplying your home.

The plug-in solar framework also does not authorise plug-in battery storage systems or other plug-connected generating equipment. The legal definition excludes devices designed to draw electricity from your home to store for later supply, apart from permitted control or auxiliary functions. Do not assume that a battery product falls under the same rules as a compliant solar device.

Export payments require a separate tariff

You do not automatically get paid for electricity exported by a plug-in solar kit. The Energy Saving Trust says you must sign up to an energy supplier’s Smart Export Guarantee tariff to receive payments. Until eligibility and a tariff are confirmed, use 0 p/kWh for exports when assessing savings.

Ofgem lists solar PV as an eligible technology, but installations must be in Great Britain and meet the applicable eligibility criteria. This does not establish that every plug-in kit qualifies. SEG payments use export meter readings, and the chosen SEG supplier determines the rate, contract length and other terms.

SEG tariff rates must be above zero, but there is no set rate. Keep export income separate from the value of electricity used at home. Ofgem’s Great Britain average electricity unit rate for Direct Debit under the cap from 1 October 2026 to 31 December 2026 is 26.32p/kWh; that is not an export tariff.