How Do Plug-in Solar Panels Work? A UK Guide (2026)

A plug-in solar kit has three working parts: solar panels that make direct current (DC), a microinverter that turns it into alternating current (AC) in step with the mains, and a lead with a standard 13 A plug. Once plugged in, the kit feeds up to 800 VA into the home's wiring. Appliances running at the time use that power first, so the household buys less from the grid. If more is produced than the home uses, the rest flows out to the grid. If the grid goes down, the microinverter switches off. It does not provide backup power.

The parts of a plug-in solar kit

On the GB plug-in route the kit must be sold complete. The IPS defines it as at least one solar panel, a grid-following inverter, a factory-assembled lead with the plug fitted by the manufacturer, the DC cables and connectors, and a mounting system.

Part	What it does	Limit on the GB plug-in route
Solar panels	Turn sunlight into DC electricity	Up to four panels, total panel power up to 2,000 W
Microinverter	Converts DC to AC, follows the mains, finds the best operating point of the panels	AC output up to 800 VA and 3.5 A
Lead with BS 1363 plug	Connects the kit to a socket on a household circuit	Supplied by the manufacturer, no adaptors or extension leads
Mounting system	Holds the panels on a balcony, wall, flat roof or in the garden	Some surfaces are not allowed (see below)
Labels and instructions	Tell the user how to install the kit and notify the distribution network operator (DNO)	Required by the IPS

Step by step: from sunlight to socket

How the power flows

Solar panelsDC electricity from sunlight
MicroinverterDC to AC, in step with the mains
13 A plug and socketfeeds the household circuit
Appliances in usetake the solar power first
Gridreceives any surplus

The kit does not charge anything or store energy. Its power is used straight away by whatever is running in the home, and any surplus goes to the grid.

The panels make DC power. The output depends on sunlight, angle, temperature and shade. A panel facing south at a good tilt produces the most. A vertical panel on a balcony railing produces less, but still a useful amount, especially in the morning or afternoon if it faces east or west.
The microinverter finds the best operating point. Its MPPT (maximum power point tracking) function keeps adjusting the voltage and current it draws from the panels, so they deliver as much power as the light allows. Many microinverters have a separate MPPT input for each panel, so shade on one panel does not reduce the output of the other.
It converts DC to AC in step with the mains. A grid-following inverter measures the mains voltage and frequency and feeds current that matches them. It cannot create its own mains supply: without a live grid to follow, it does not feed in.
The power enters the home through the socket. The kit is plugged into a socket on a normal household circuit. From there, electricity flows to whatever is using power at that moment, anywhere in the home, not only on that circuit.
The meter sees less import. While the kit is producing, the home draws less from the grid. When production is higher than consumption, the surplus flows out through the meter to the grid.

Why the output is capped at 800 VA

The IPS limits the AC output to 800 VA and 3.5 A. The panels may total up to 2,000 W, more than the inverter can deliver. This is deliberate: a larger panel area gives more output in the morning, in the evening and in winter, when the panels produce well below their rating. At midday on a bright summer day, the microinverter simply caps its output at the limit.

The 3.5 A limit keeps the extra current that the kit adds to a household circuit small. Two related rules apply. When the total panel power is above 960 W, the manufacturer must advise the customer to consider a professional assessment first. And only the supplied lead and plug may be used, with no extension leads, multi-way adaptors, travel adaptors or RCD adaptors.

What keeps the plug safe

The concern people raise most often is the plug: could its pins be live when it is pulled out? A grid-following microinverter is designed to stop feeding in as soon as it no longer sees the mains. This is called anti-islanding protection. When the plug is pulled, or when there is a power cut, the inverter no longer detects the mains and shuts down within the time set by the grid connection rules. The kit must be type tested against Engineering Recommendation G98, and the IPS sets further safety requirements for the plug and the lead.

The IPS also sets rules for where the kit may go:

One kit per household under the current G98 rules, plugged into a socket circuit, not a lighting circuit.
Modern residual current protection (RCBOs) is advised. Homes with old fuse boards should be checked by an electrician first.
Mounting is not permitted on ACM, MCM, HPL or timber cladding, on timber balconies, or on buildings undergoing external wall or building safety remediation, and panels must not be fixed with cable ties, rope, straps or tape alone.

What it does not do

No backup power. Because of anti-islanding protection, the kit switches off during a power cut. For backup, the home needs a battery system with a backup output, installed by an electrician.
No storage. Products with a battery are outside the GB plug-in route, and the IPS requires the instructions to warn against using the kit with a battery system. Home batteries are installed as a separate, fixed-wired system. See 800 W balcony solar with a battery for the different designs.
No mix and match. The kit is registered as a complete product. Adding panels, swapping the inverter or using another lead takes it outside the registered design.

How much power to expect

Output varies a lot with orientation, shading and the season, so treat any figure as a rough guide. The government has estimated that a household could save up to about £110 a year with a plug-in solar device. What matters most is how much of the solar power is used at the time it is produced: homes with daytime consumption, such as a fridge, home office equipment or a heat pump running during the day, get more value than homes that are empty all day.

Frequently asked questions

Do plug-in solar panels work during a power cut?

No. The microinverter needs the mains to follow and switches off when the grid is down. This anti-islanding protection stops it from feeding power into lines that may be under repair. Backup power needs a battery system with a backup output, installed by an electrician.

Can I plug the kit into an extension lead?

No. On the GB plug-in route only the lead and plug supplied with the kit may be used. Extension leads, multi-way adaptors, travel adaptors and RCD adaptors are not permitted, and the plug carries a warning saying so.

Does the power only go to the appliances on the same socket?

No. The kit feeds the household circuit it is plugged into, and from there the power is used by whatever is running anywhere in the home. Any surplus goes to the grid.

How many plug-in solar kits can one home have?

One per household under the current G98 rules. The IPS itself would allow one per final circuit, but the G98 limit applies.

Do I need to tell anyone after installing a kit?

Yes. The customer must notify the distribution network operator (DNO) when a plug-in solar device is installed or removed. Current guidance, for example from the London Fire Brigade, says to do this within 28 days of installation.

Can I add a battery to a plug-in kit later?

Not as part of the plug-in kit. Battery products are outside the GB plug-in route. A battery can be installed as a separate, fixed-wired system by a competent installer and notified under the normal G98 or G99 process.

How VaySunic can help

VaySunic develops microinverters and complete plug-in solar kits in-house, with its R&D and manufacturing centre in China and European headquarters in Germany. For UK partners, see our plug-in solar kits and the SolarCore P2 microinverter. On the plug-in route the complete kit, not the microinverter alone, is what gets registered, so contact us for the current UK status of a specific kit. Retailers and wholesalers can find terms and support in our distributor programme. Homeowners who want a kit installed can ask us to put them in touch with a local partner.