Two plug-in solar kits, both on sale in the UK right now, both perfectly fine to plug in: one advertised as 460W, the other as 1260W.

If the limit is 800W, how is the 1260W one allowed? Because the two numbers are measuring different things. The limit is about what actually reaches your sockets. The number on the box is what the panels make in bright sun.

Two different numbers, two different jobs

The panels make a kind of electricity your house cannot use directly. Every kit therefore contains a small box — an inverter — that converts it into the kind that comes out of your sockets, and that box has a ceiling of its own. It is the inverter, not the panels, that decides how much power actually reaches your wall.

The proper names, now that you know what they mean: the panels produce DC, your sockets run on AC, and the figure in the rules is the inverter's AC output.

SI 2026/848, the law that legalised plug-in solar on 27 August 2026, caps a "plug-in microgenerator" at a maximum rated AC output of 800 watts. That is the inverter's output — the number that matters for the law — not the panels' combined rating.

So a kit can carry 1,260W of panels and still be legal, provided its inverter caps what it actually feeds into the socket at 800W or below. On the ENA's device register, UKSOL's "Pro Compact" kit (460W of panels) and its "Pro Max" kit (1,260W of panels) are both registered with an 800W AC rating. Same limit, very different-looking boxes.

Why sellers quote the bigger number

Panel wattage (DC) is the industry's usual shorthand, and it is also the bigger, more impressive-sounding figure — a 1,260W kit sounds like more than an 800W one, even though both may deliver exactly the same amount of usable power to your home. Quoting DC isn't dishonest on its own. It becomes a problem only when a shopper assumes the headline number is the one the law is checking.

Why so many inverters say "799VA"

Look at enough spec sheets and you will see inverters rated at 799VA rather than 800W or 800VA. That is not a rounding quirk. Manufacturers set the cap a whisker under the legal limit deliberately, so there is no argument at the boundary about whether a device that measures at exactly 800W under test conditions has crept over it.

The practical test

Before you buy, ask the seller one question: "What is the inverter's maximum AC output?"

  • If they answer with a wattage at or under 800W, the device meets the output condition of a plug-in microgenerator (check the other three conditions — solar-only, standard plug, grid-parallel, no import-to-store — separately).
  • If they only give you the panel wattage, ask again. A seller who cannot state the AC figure is not able to tell you whether their own product is legal.
  • If the number is over 800W, it does not qualify as a plug-in microgenerator, whatever it is marketed as.

You can check the same figure yourself against the manufacturer's entry on the ENA Connect Direct register, which records a registered AC capacity for every listed device.

Our comparison table lets you filter and sort by AC output directly, so you never have to do the panel-vs-inverter maths yourself.

Related reading: we checked every plug-in solar kit on sale in the UK against the ENA register, and why a battery kit isn't plug-in solar.