Plug-in solar rules and limits explained

The plug-in solar rules in Great Britain are short, specific and unforgiving. Here is every limit, what it means in practice, and how to tell whether a kit you are looking at actually sits inside them.

Summary table

The 800VA output cap

This is the headline number. Whatever the panels are producing, the inverter may never push more than 800VA into your home. On a bright June afternoon a well-sized kit will sit at the cap for hours; in December it may never reach half of it. For scale, 800VA runs a fridge, a couple of laptops, a monitor and a router with room to spare — but it is about a third of a typical fan heater and nowhere near an electric shower.

The 3.5A current limit

The current limit exists so the device stays comfortably within the rating of an ordinary 13A socket and its circuit, with plenty of margin for whatever else is plugged in nearby. It is enforced by the inverter, so it is not something you can breach by accident — but it is a reason the connection must go directly into a socket rather than through an extension lead, where cumulative loading is unpredictable.

2,000Wp of panels — and the 960Wp threshold

DC panel capacity is capped at 2,000Wp. Because the AC side is limited to 800VA, fitting more panels than the inverter can pass is deliberate, not wasteful: extra panel area brings the system up to full output earlier in the morning, later in the afternoon, and on overcast days. The trade-off is cost and mounting space.

Above 960Wp of panels, a professional electrical assessment is advised. In practice that means asking a qualified electrician to look at the circuit you intend to use, the state of your consumer unit and where the panels will be mounted. It is advice rather than a hard stop, but it is sensible: larger arrays mean more hardware, more wind load and more cable.

One device per household

You may connect one plug-in solar device per household under G98. Two 800VA devices to make 1,600VA is not permitted, and it is not a grey area — the second connection is unregistered generation. Households wanting more than 800VA should be looking at a conventional, professionally installed system with its own connection application.

Battery-free only

Plug-in solar devices must have no battery storage. This keeps the device predictable: it generates when the sun is out and does nothing when it is not. Attaching a battery — even a portable power station wired into the output — takes the installation outside the plug-in category and outside its connection permission.

Direct socket connection only

The plug goes into a socket outlet. Not an extension lead, not a trailing block, not a timer plug, not an outdoor adaptor. If the cable does not reach, the answer is to move the panels or to have an electrician fit a socket in a better place — never to extend it.

Choosing the socket

• Use an outdoor-rated socket if the connection point is outside.
• Pick a socket you can reach easily, so the device can be isolated quickly.
• Keep the cable route clear of mower lines, doors and anywhere it can be trodden on.

IPS v2.0, G98 and ENA Connect Direct

Three names you will see repeatedly. IPS v2.0 is the interface protection specification the inverter is built to; it is what makes the device shut down on loss of mains, which is why plug-in solar does not work in a power cut. G98 is the engineering recommendation for connecting small generators, and is where the one-per-household rule and the registration duty live. ENA Connect Direct is the register: it lists products assessed as Compliant, and it is where you both check a product before buying and register your device afterwards.

Our registration guide covers the register in detail, and is plug-in solar legal in the UK? explains how the rules came about.