Plug-in (balcony) solar explained

What makes a kit legal

• The whole kit must be approved, not just the inverter. It must meet the government’s Plug-in Solar Device specification and be listed as compliant on the Energy Networks Association’s register. A listing that only says “800W” or “UK plug” is not proof.
• It plugs directly into a suitable socket. No extension leads, multi-way, travel or RCD adaptors.
• You register it before you use it, on the UK Plug-In Solar Registration website, which the Energy Saving Trust says is a legal requirement. Your network operator must also be told when you connect and disconnect it.
• It has no battery. Kits with a built-in battery are outside the plug-in rules.
• One device per household is allowed for now.
• Not in Northern Ireland yet. Kits can be sold there, but not plugged in, until Northern Ireland’s own rules change.

Is your home suitable?

The Energy Saving Trust’s checklist says:

• Check your fuse box. Modern consumer units have switches labelled RCD, RCBO or MCB. If yours has older rewireable fuses, don’t install plug-in solar.
• Choose the right socket: one on a circuit that doesn’t also supply lighting or fixed appliances such as a boiler or cooker. An outdoor socket must be weatherproof and fitted by a qualified electrician.
• Call an electrician if you are unsure about the wiring, need a socket moved or added, or your panels add up to more than 960 W.
• Test the protection about every six months by pressing the test button on your consumer unit while the panels are generating. If it doesn’t trip, unplug the kit and call an electrician.
• Fix the panels securely so they can’t move or blow over. The government specification rules out timber balconies and cladding, certain other cladding types, and walls on the boundary with a neighbour.

Why more than 800 W of panels can help

Panels only produce their full rated power in ideal conditions. Even on a clear day, two 400 W panels will be close to 800 W for only a short time around midday, and much less in the morning, evening and winter. The rules let you have up to 2,000 W of panels behind the 800 W inverter. The inverter still caps the output, but it stays at or near the cap for longer. Bear in mind that a modern panel can be around 2 metres long and over a metre wide, so you need the space.

What will it save?

The Energy Saving Trust says a compliant kit can generate around 700 kWh a year and save around £100 a year if someone is home in the day, or around £70 if not. The government’s figure is up to £110 a year.

The catch is timing. Your saving comes only from electricity you use at the moment it is made. If the panels are producing 800 W but your home is only using 200 W, the other 600 W flows out to the grid, and plug-in kits are not normally paid for that. To use more of it:

• run the washing machine, dishwasher or tumble dryer in the middle of the day;
• use timers and smart plugs for appliances you can shift;
• in summer, fans and air conditioning tend to run when the sun is strongest, which soaks up the output.

Plugging in, or having it wired in?

Plug-in solar is designed to be simple: you plug it in yourself. The government says compliant kits are safe and compatible with UK wiring, after independent safety testing, and the product rules include safety requirements.

Some solar experts still prefer not to feed power back through an ordinary socket, especially in older homes, where the wiring may be old, altered over the years, or simply never designed with that in mind. The Energy Saving Trust’s own checklist reflects the same caution: no older fuses, the right kind of circuit, and an electrician if you are unsure.

The alternative is to have a solar system wired in: an electrician connects it to your consumer unit on its own protected circuit, instead of through a socket.

Having it wired in has three main advantages:

1. A connection made for the job. The system gets its own circuit, cable and protective devices, installed and tested to wiring standards, rather than relying on a socket designed for appliances to draw power from.
2. No 800 W cap. The 800 W limit applies only to the plug-in route. A wired-in system can typically go up to about 3.68 kW on a normal single-phase supply under the G98 notification process.
3. It can include a battery. Spare power at midday is stored for the evening instead of flowing out to the grid unpaid.

The trade-offs: it costs more, because you pay for an electrician and usually more equipment. And it is no longer the plug-in route, so the normal rules apply: the installer notifies your network operator, the electrical work must meet building regulations, the usual planning rules apply to where the panels go, a battery has to be sited safely, and you will only be paid under the Smart Export Guarantee if the system is installed and certified under MCS or an equivalent scheme.

A sensible approach: if your home has a modern consumer unit and you want something small and cheap, a compliant plug-in kit is a reasonable way to start. If your wiring is older, you are unsure about it, or you would like more output or a battery, ask a qualified electrician about a wired-in system. Many people with older wiring choose to have an electrician check it first either way.

Registering and telling the network

Register the kit on the UK Plug-In Solar Registration website before you use it. You need your name, postcode and the kit’s make and model, which must match the register. Keep the confirmation. The specification also requires your network operator to be told when you connect and disconnect the kit, and you may need to notify it separately if you already have solar or a battery and the extra kit means your home could export more than a set amount.

Planning, renting and insurance

In England, plug-in solar is covered by the permitted development rules updated on 27 August 2026, but it must not be fixed to a wooden wall, fence, gate or balcony, or a timber-clad exterior. Wales and Scotland have their own rules. Tenants and leaseholders need permission from their landlord or freeholder. Tell your home insurer. See Do I need permission? and Renting, leasehold and flats.