Can I Add Plug-In Solar Panels to an Existing System? The UK Rules for 2026
In most homes, yes. The answer to can I add plug in solar panels to existing system comes down to one number: the combined capacity of every generator on your property must stay within 16 amps per phase, which is about 3.68 kW on a standard single-phase supply. Stay under it and a plug-in kit can run alongside your rooftop panels with a simple notification. Go over it and the connection moves into a process that needs your network operator's agreement.
The same rules, in force since 27 August 2026, also set how many kits you can have, how to connect them and where they can go.
How the 16 A limit applies to an existing system
Ofgem approved the change to Engineering Recommendation G98 that allows plug-in solar on 11 August 2026. Its decision states that a plug-in device may connect and operate alongside permanently wired generation provided the aggregate registered capacity of all generators in the home does not exceed G98's existing 16 A per phase limit, and that above this limit the G99 requirements apply (Ofgem, DCRP/MP/26/02, 11 August 2026).
The same decision caps a plug-in device at a registered capacity of 800 W. At the nominal 230 V, 16 A is 3.68 kW, so an existing system registered at up to about 2.88 kW leaves room for a full-size plug-in kit. Your existing figure is the capacity on your original G98 or G99 paperwork, usually the inverter rating rather than the total of the panels.
| Existing system (registered capacity) | Plus an 800 W plug-in kit | Connection route |
|---|---|---|
| 2.0 kW | 2.8 kW | Within G98: notify |
| 2.88 kW | 3.68 kW | At the G98 limit: notify |
| 3.0 kW | 3.8 kW | G99: speak to your DNO first |
| 3.68 kW or above | 4.48 kW or more | G99: speak to your DNO first |
Many recent rooftop systems use a 3.6 kW or 3.68 kW inverter, right at the G98 ceiling. If yours does, any plug-in kit takes the property over, so speak to your distribution network operator (DNO) before plugging it in.
What happens when both systems run together
A plug-in kit feeds the circuits on your side of the meter, so the house uses its output first and any surplus leaves through the same meter as your rooftop export. Three interactions are worth checking before you buy.
- Export limits: if your rooftop system is export-limited, ask your installer how the limit is enforced. Where it is measured by a clamp or meter at the incoming supply, the inverter sees the plug-in kit’s surplus and holds back its own output. Where it is only a fixed setting inside the inverter, the kit is invisible to it, and total export can rise above the figure agreed for your connection.
- Batteries: a battery whose inverter monitors the incoming supply and can charge from AC may soak up the plug-in kit’s surplus. Whether yours does depends on that inverter’s settings, not simply on whether the battery is AC- or DC-coupled.
- Feed-in Tariff systems: if your rooftop panels earn FIT payments, ask your FIT licensee before adding any generation. The kit is separate equipment, but older agreements vary.
How many plug-in solar panels can I have?
One plug-in device per household, though that device can carry more than one panel.
The government's product specification allows one device per final circuit, but it states that the network rules take precedence, and amended G98 restricts the number to one per household until G98 itself is changed (DESNZ, Plug-in Solar Device Interim Product Specification v2.0, July 2026, section 1).
Within that single device, the specification allows up to 2,000 W of panels on an inverter capped at 800 VA and 3.5 A. Extra panel area helps on dull days because the inverter reaches its cap more often. Above 960 W of panels, manufacturers must advise you to have your existing wiring assessed by a professional first (section 4.1).
How to install plug-in solar panels legally
Under SI 2026/848, a plug-in microgenerator must not be installed or operated unless it complies with the product specification (SI 2026/848, regulation 3, in force 27 August 2026 in England, Wales and Scotland). In practice that means five checks:
- Buy a complete kit: panels, inverter, cables and mounting are tested and listed together, so choose a model listed as compliant on the ENA Connect Direct register, which the specification requires manufacturers to use.
- Use a socket circuit only: not a lighting circuit, and not a spur that supplies a cooker, boiler or other fixed equipment (specification, section 8.3.3).
- Plug in directly: no extension leads, multi-way adaptors, travel adaptors or RCD adaptors, and on the panel side only the manufacturer's own cables and connectors. Y-connectors are not permitted (section 6.2).
- Check your consumer unit: if it still has rewireable fuses rather than circuit breakers, have an electrician look at it before installing anything.
- Register before you switch on: amended G98 requires householders to notify their DNO of a plug-in installation, as set out in Ofgem's decision above. Network operators such as Electricity North West direct customers to the UK plug-in solar registration website and ask for registration before the device is used. You need your name, postcode and the device's make and model.
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Good to know
To find out which circuit an outdoor socket is on, switch off one breaker at a time in the consumer unit and note which sockets go dead. If the socket also loses the garden lights or an outside boiler, it is on a circuit the rules exclude.
Where can plug-in solar panels go?
In England, the planning rules changed on the same day. SI 2026/896 extends permitted development to plug-in solar with conditions that depend on where the panels are fixed (SI 2026/896, articles 3 and 4, in force 27 August 2026).
- On the house: a wall or balcony fixing may protrude up to 0.4 m, or 0.2 m where the wall faces a highway. Panels may not go on a wooden wall, balcony or enclosure, or on timber-clad parts of the house.
- In the garden: a free-standing frame is limited to 2 m high within 5 m of the boundary (1 m if it is also in front of the house) and 4 m elsewhere, with a total panel area of 9 m². It may not be fixed to a wooden fence, gate, wall or other enclosure.
- Listed buildings and conservation areas: permitted development does not cover listed homes, and in a conservation area wall or balcony panels facing a highway are excluded, so apply to your council.
The product specification adds fire-safety exclusions that apply everywhere: no installation on ACM, MCM, high-pressure laminate or timber cladding, on timber balconies, or on buildings undergoing external wall remediation (section 5). The planning conditions above are England's, so elsewhere check with your council. The electrical amendment in SI 2026/848 extends to England, Wales and Scotland but not to Northern Ireland (regulation 1(4)), so plug-in solar is not yet an option there. For help choosing a kit, see our plug-in solar beginner's guide.
Frequently asked questions
Do I need to tell my DNO if I already have rooftop solar?
Yes. Register the plug-in device either way. If the combined capacity stays within 16 A per phase, that registration is the notification. If it goes over, the G99 process applies, so contact your DNO before connecting the kit. The assessment covers the property's combined capacity, not just the new device.
Can I plug a second kit into a different circuit?
Not at present. Amended G98 limits each household to one plug-in device, however many circuits the house has. To add capacity, put more panels on that one device, up to 2,000 W.
Can I charge a battery from plug-in solar?
Not through a plug-in battery. Ofgem's decision states that plug-in electricity storage devices remain prohibited from being sold, supplied or used in the UK (Ofgem decision letter, 11 August 2026). An existing hard-wired, AC-coupled battery may still absorb the kit's surplus.
Do I need an electrician to install a plug-in kit?
Not to plug it in. Ofgem's decision removes the installer-competence requirement for plug-in devices, so a householder can connect one, but the wiring in the home must still meet BS 7671. Call an electrician if you need a new outdoor socket, if your consumer unit has rewireable fuses, or if the kit carries more than 960 W of panels and the manufacturer advises an assessment.
The short answer
Adding plug-in solar to an existing system is allowed and, for a rooftop installation registered at under about 2.88 kW, it is a matter of buying a listed kit, plugging it into a suitable socket circuit and registering it. Above that, the same kit needs your DNO's agreement first.
Either way the limit is one device per household. Check your existing paperwork for its registered capacity before you order. Our guide to plug-in solar panels covers what to expect once it is running.
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