When the final Interim Product Specification was published on 16 July 2026, most of the coverage led on the headline limits — the 800VA output cap, the UK plug, the battery exclusion. One change was widely reported as the practical headline: the draft's one device per household limit became one device per power circuit, and a lot of coverage went straight from there to “most homes can run two or three kits”.
That step does not follow. The specification is not the only rule governing what you may connect. Network connection requirements apply alongside it, and Engineering Recommendation G98 Issue 2 Amendment 1 2026 still restricts a household to one device — a restriction the specification itself flags, and which stands unless and until G98 is amended. The per-circuit allowance is genuine, and it is dormant. From 27 August 2026the answer to “how many kits can I run?” is one, regardless of how your consumer unit is arranged.
The rest of this article is still worth reading, because the per-circuit definition decides what happens if and when G98 is amended — and because “one per circuit” is widely being heard as “one per socket”, which is wrong twice over. Here is the accurate version.
What a “Power Circuit” Means in a UK Home
Open the cover flap on any modern consumer unit and you will see a row of switches, each one a miniature circuit breaker (MCB) or an RCBO. Each of those devices protects exactly one circuit. Everything downstream of it — all the cable, all the accessories, all the socket outlets — is that one circuit.
For plug-in solar, the circuits that count are the ones with BS 1363 socket outlets on them. In UK homes those come in two flavours:
- Ring final circuits. The traditional British arrangement, and still the most common. A single cable leaves one protective device, loops through a run of socket outlets, and returns to the same terminals in the consumer unit — a ring. Typically protected at 32A, and often serving an entire floor of a house.
- Radial socket circuits. A single cable from one protective device out to a run of sockets, with no return leg. Typically protected at 20A or 32A. Common in newer builds, flats, and for dedicated kitchen or garage circuits.
A ring final circuit is one circuit, not two. This is the single most common misunderstanding. The ring has two current paths, but it has one origin and one protective device, so it is one circuit — and under the specification it takes one plug-in solar device, whether it serves four sockets in a flat or twenty across a whole floor.
Circuits without sockets would not count either. Lighting circuits (usually protected at 6A), cooker circuits, shower circuits and immersion heater circuits are all separate circuits, but none of them has a socket you could plug a kit into, so none of them would count towards a per-circuit allowance.
How Many Circuits Do You Actually Have?
For most UK homes the answer is two or three. A typical house has an upstairs socket circuit and a downstairs socket circuit, and many post-1990s properties add a separate kitchen circuit because of the load from appliances. Flats frequently have fewer — a one-bedroom flat may be served by a single socket circuit.
Be clear about what that count currently buys you, though: nothing extra. While Engineering Recommendation G98 Issue 2 Amendment 1 2026 caps the household at one device, a house with three socket circuits and a studio flat with one are on exactly the same limit. Counting your circuits is preparation for a rule change, not permission to run more kits today.
Garage, outbuilding and outdoor socket arrangements vary enormously. Some are genuinely separate circuits; others are spurred off an existing one and are therefore part of it. That variation is exactly why you should not assume.
How to check — and where to stop
You can establish this from outside the consumer unit. Every circuit should be identified on the schedule or label on the unit's front — the socket circuits are usually described as “sockets”, “ring” or by area, and are normally protected at 32A or 20A. Count those, and that is your starting figure.
If the labelling is missing, illegible, contradicted by an obvious later alteration, or you simply cannot tell which sockets belong to which way, stop there and ask a qualified electrician. The final specification requires manufacturers to supply guidance on identifying circuits, and DESNZ's own advice is to consult an electrician if you are unsure.
Do not open the consumer unit, and do not treat circuit identification as a DIY job on wiring you do not know the history of. See our electrical safety guide for where the line sits.
Why the Rule Changed
The draft specification published in June proposed one device per household. It drew heavy criticism, and 61% of consultation respondents backed a per-circuit limit instead. The government agreed and changed it in the final version — but the specification records in the same breath that GB network connection requirements also apply, and that Engineering Recommendation G98 Issue 2 Amendment 1 2026 restricts connections to one device per household unless and until that is amended. The specification changed; the network rules have not.
The logic is straightforward once stated. The engineering concern behind any limit here is a property of the circuit, not of the dwelling: how much generation is being injected into one set of conductors, protected by one device, and how that interacts with a circuit topology — the ring — that BS 7671 has never really contemplated a generator sitting inside. That is a design ambiguity rather than a history of failures, and it is why the output cap is set where it is: 3.5A injected into a circuit protected at 32A is small against the circuit's rating. One device per circuit stops that small injection being stacked several times over onto the same conductors.
A per-household rule would have imposed the same restriction on a four-bedroom house with three socket circuits as on a studio flat with one, without any engineering justification for doing so. The per-circuit version ties the limit to the thing the limit is actually about. That reasoning has been accepted at the product-specification level and not yet at the network level, which is why the house-and-flat equivalence the change was meant to end is still the position on the ground. We covered the full set of changes between the draft and final specifications in our report on the legalisation date.
What Changes If G98 Catches Up
Nothing here is available yet, and we will say plainly on this page when it is. But it is worth understanding what the per-circuit allowance would unlock, because it is the reason the change was made.
If the network requirements are amended to match, two circuits would mean up to two devices — up to 1,600VA of AC output and up to 4,000W of panels, each device still individually capped at 800VA and 2,000W. That would open up the arrangement that works best in practice: one array facing east and one facing west, spreading generation across the morning and the evening rather than piling it all into a midday peak you cannot use.
We have no date for that amendment, and DESNZ has not published one. The specification says only that the household restriction applies “unless and until” G98 is amended, which is not a commitment that it will be. Plan around one device, and treat a second kit as a possible future rather than a purchase to budget for.
What This Means If You Are Planning a Setup
Buy one compliant kit, and put it where it will generate best. The constraint that bites first is rarely the circuit count in any case: it is space, mounting options, and — above all — self-consumption. Generation only pays if you are actually using the electricity when it is produced, because the export side of the equation offers plug-in owners nothing under current arrangements. Run your own numbers through the savings calculator rather than the headline figures.
Notifying your distribution network operator is not optional, either. The specification requires the product to carry a statement that notification about connection and disconnection is mandatory, with a link to instructions and a QR code pointing to the registration and deregistration guidance. What is outstanding is the simplified registration route, which is still in development — not the obligation.
And the usual caveat applies to everything above: none of it matters for a device that is not actually compliant. You can check any kit against all ten of the specification's rules, including this one, with our plug-in solar compliance checker, and see the current state of play on the certification tracker. For everything else that changes on the in-force date, see what actually changes on 27 August 2026.
Sources: DESNZ, Plug-in Solar Device Interim Product Specification and consultation government response (16 July 2026), via gov.uk; SI 2026 No. 848 via legislation.gov.uk. © Crown copyright 2026, Open Government Licence v3.0.
Frequently Asked Questions
How many plug-in solar devices can I actually connect?
One, however many socket circuits your home has. Two rules apply at the same time and the tighter one wins. The Interim Product Specification permits one device per household final ring circuit, but its own note records that GB network connection requirements also apply, and that Engineering Recommendation G98 Issue 2 Amendment 1 2026 restricts this to 1 device per household "unless and until that is amended". G98 has not been amended, so 1 is the limit from 27 August 2026.
What counts as one power circuit?
A circuit is everything fed by a single protective device — one MCB or RCBO — in your consumer unit. For plug-in solar the circuits that matter are the ones with socket outlets on them. A ring final circuit counts as one circuit however many sockets it serves, and a radial socket circuit counts as one as well. That definition decides what the per-circuit allowance would mean in your home once network rules catch up; it does not raise the number of devices you may connect today.
Does a ring main count as one circuit or two?
One. A ring final circuit is a single cable that leaves one protective device, loops through a run of socket outlets and returns to the same terminals. It has two current paths but a single origin and a single protective device, so it is a single circuit — and under the specification it takes a single plug-in solar device, whether it serves four sockets or twenty.
How many plug-in solar kits can a typical UK home run?
One, whatever the size of the property. Most UK homes have two or three socket circuits — commonly an upstairs circuit, a downstairs circuit and sometimes a separate kitchen circuit — and under the specification alone that would mean two or three devices. It does not, because Engineering Recommendation G98 Issue 2 Amendment 1 2026 still caps connections at 1 per household. A four-bedroom house and a studio flat are on the same limit until G98 is amended.
Can I plug a second kit into an extension lead to get around the rule?
No, and a second kit is not permitted anywhere in the household at the moment in any case. An extension lead does not create a new circuit — everything plugged into it is still fed by the same protective device in the consumer unit. Connect a plug-in solar device only in the way its manufacturer's instructions specify.
Why did the rule change from one per household to one per circuit?
Because the engineering constraint is a property of the circuit, not of the dwelling. The draft specification proposed one device per household; 61% of consultation respondents backed a per-circuit limit instead, and the final specification adopted it. The change is real but it is not yet operative: the specification notes that Engineering Recommendation G98 Issue 2 Amendment 1 2026 continues to restrict connections to 1 device per household unless and until it is amended, and network requirements apply alongside the specification rather than being replaced by it.
How do I find out how many socket circuits I have?
Look at the schedule on the front of your consumer unit, where each protective device should be labelled with what it feeds. Socket circuits are usually labelled as sockets or rings and are typically protected at 32A or 20A; lighting, cooker and shower circuits are separate and have no sockets to plug into. If the labelling is missing, out of date or ambiguous, ask a qualified electrician rather than guessing. This is worth knowing regardless — it tells you which circuit your one device is on, and what your position would be if the network rules are amended.
Related reading
What Actually Changes on 27 August 2026
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Is Balcony Solar Safe? UK Electrical Safety Guide
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UK Plug-in Solar Legalisation Timeline — Every Key Date
Every key date in UK balcony solar regulation, from Germany's early moves to the 27 August 2026 legalisation. Updated July 2026.
Check a kit, or check the numbers
Run any plug-in solar kit through the specification's rules, or see what a single compliant kit could realistically save you.