Helpful video reference. We use eFIXX's "We Tested Plug-In Solar. The Industry Got This Wrong." as the video reference here. eFIXX is a UK electrical trade publisher that physically tested plug-in solar units on the bench -- including anti-islanding behaviour, RCD trip performance and two-inverter scenarios -- rather than reading a spec sheet. Worth watching before you buy.
1. What plug-in solar is
A plug-in solar unit -- also called a balcony power station or micro-inverter system -- combines one or two solar panels with a small grid-tied inverter. The inverter converts the panels' DC output to AC and feeds electricity directly into the home's wiring, reducing what the household draws from the grid at that moment.
The concept became popular in Germany, the Netherlands and France, where apartment dwellers with balconies could buy a kit and connect it themselves. Output is limited -- typically 300W to 800W per unit -- but for a home that uses electricity during daylight hours, the savings on import can be meaningful. A 600W system running for six hours on a good summer day offsets around 3.6 kWh, which at 24p/kWh import is about 87p a day.
2. The 2026 regulatory change
Before April 2026, there was no compliant route to install a plug-in solar unit in the UK under BS 7671. Connecting a grid-tied inverter to the household wiring constituted a fixed electrical installation, with all the associated notification and inspection requirements -- essentially the same process as a full solar PV system.
BS 7671 Amendment 4 was ratified in March 2026 and came into force on 15 April 2026. The key change was a new Section 745: microgeneration up to 800W is reclassified from a fixed electrical installation into a category that can be installed on a dedicated hard-wired circuit, separate from the general wiring. The electrician installs and certifies the circuit; the homeowner connects the plug-in unit to that circuit.
3. The 800W limit and what it means
Section 745 permits a maximum of 800W per circuit, and only one plug-in microgeneration unit per circuit. This limits output to roughly one-quarter of a typical 3.5 kWp domestic solar installation.
At 800W peak and a UK average of three to four peak sun hours per day, a compliant installation might generate 900 to 1,200 kWh per year in south-east England. That is a meaningful offset for a household that uses electricity during the day -- roughly equivalent to running a fridge-freezer for a year -- but it is not a substitute for a full solar PV system. The appeal is the lower installation cost and the ability to take it with you if you move.
4. Anti-islanding and safety requirements
The most important safety requirement for any grid-tied micro-inverter is anti-islanding protection. If the grid loses power -- whether due to a fault or planned maintenance -- the inverter must detect the loss and shut down within 200 milliseconds. Without this, the inverter would continue pushing electricity into the grid, creating a danger for anyone working on the lines who believes the supply is dead.
All compliant units must meet BS EN 61727 (characteristics of the utility interface) and carry G98 registration for single-phase systems below 3.68 kW. In practice, every reputable micro-inverter from European manufacturers already meets this standard -- but it is worth verifying on the data sheet before buying.
eFIXX's bench testing found that most units they tested did shut down promptly. However, they also found that running two inverters on a shared circuit produced unexpected interactions. Under Section 745, one unit per circuit avoids this problem entirely.
5. What a compliant installation looks like
A registered electrician installs a dedicated radial circuit from the consumer unit to the location where the plug-in unit will be connected. The circuit includes:
- An RCBO (combined MCB and RCD) in the consumer unit, sized for the circuit cable
- A suitable socket or terminal at the point of connection -- some installers use a 16A commando socket, others use a dedicated fused connection unit
- A label identifying the circuit as a microgeneration supply
The electrician will issue a Minor Electrical Works Certificate or, if a new circuit is run from the consumer unit, an Electrical Installation Certificate. This is Part P notifiable work. The homeowner then plugs or connects the micro-inverter unit to the dedicated terminal -- that final step is not electrical installation work under the rules.
6. How it compares to a full solar PV installation
A full solar PV system with a 4 kWp array typically generates 3,400 to 3,800 kWh per year in Kent and costs £6,000 to £9,000 installed. A 800W plug-in unit costs perhaps £400 to £700 for the panel and inverter, plus electrician costs for the dedicated circuit (roughly one to two hours of work). Output is around a quarter.
The plug-in route suits renters who cannot alter the building structure, homeowners who want to dip a toe into solar before committing to a full system, and properties where roof access or ownership issues prevent standard installation. It does not qualify for MCS certification (which requires a full system), so it cannot register for the Smart Export Guarantee in the same way.
For most homeowners with a suitable roof, a full MCS-certified system with Smart Export Guarantee registration will deliver a better long-term return. But for those who cannot or do not want a full installation, the new 2026 rules at least provide a compliant and safe route.
When to call us
If you want a dedicated circuit installed for a plug-in solar unit, or want advice on whether a full solar PV system makes more sense for your property in east Kent, call. Richard can talk through the options without a sales angle.
Solar options in Sandwich or east Kent?
Richard can install the dedicated circuit for a plug-in unit or advise on full solar PV. No pressure, just honest information about what makes sense for your property.
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