Plug-In Solar on a Flat Roof: UK Guide

Since 27 August 2026, a verified plug-in solar kit can be sold and used in Great Britain, and a flat roof is one of the better places to put one. On a balcony you get whatever direction the building faces. On a flat roof you choose: face the panels south, tilt them, keep them clear of shade. That matters for the bill. The government's estimate of £70 to £110 a year has its top figure modelled on a panel tilted at 30° facing south, and a near-vertical balcony panel usually sits near the bottom of the range.

The catches are the ones a balcony doesn't have: who owns the roof, what holds the frame down in wind, how high it stands, and how the cable gets back to a socket. This guide takes them in turn.

Verified kits sold as flat-roof versions

A kit can only use the plug-in route if it has a Compliant record on the ENA Type Test Register, and the register assesses each kit as sold, mounting included. At our 13 November 2026 pull, 4 verified records name a flat-roof version in the model, from Thunder Energy and EcoFlow:

1 of them has a listing we've matched to the exact reference. For the rest, a listing for the standard version is a different record, so don't take its approval as covering the flat-roof one. One more verified record names ballast mounts without saying flat roof: Worldwide Solar, 2 × JA Solar JAM54D40 bifacial, Hoymiles HMS-800-2WB, ballast mounts. Other kits may allow a flat roof in their instructions, which is what counts. Match the reference on the box or QR label to the register, suffix and all; our certification tracker lists all 145 verified kits, and the where to buy guide names the shops.

Planning permission for a flat roof in England

SI 2026 No. 896, in force since 27 August 2026, amended the permitted development rules for solar at homes. It defines plug-in solar as solar PV intended for connection by a standard plug and socket, and amends “solar PV” to read “including plug-in solar”, so a plug-in kit sits inside permitted development, within limits. For a house, or a building in its garden, the flat-roof limit is this: the highest part of the installation may be no more than 0.6 metres above the highest part of the roof, excluding any chimney.

Measure the top edge of the frame, not the panel's middle. A steeper tilt raises the top edge, so a tall frame can take you over the line. On top of the height limit:

• Listed buildings and scheduled monuments: no permitted development for solar.
• Conservation areas: on article 2(3) land, which includes conservation areas, you have to ask the council for prior approval of a flat-roof installation first. Separately, nothing is permitted on a wall, balcony or roof enclosure which fronts a highway.
• Wooden and timber-clad surfaces: no plug-in solar on a wooden wall, balcony or enclosure, or on timber cladding.
• Panels have to be sited, so far as practicable, to minimise their effect on the building's look.

One detail catches roof terraces. The Order defines a “roof enclosure” to include any balustrade, railing or parapet on a roof. On our reading, a panel clamped to the parapet falls under the enclosure limits, protruding no more than 0.4 metres beyond it (or 0.2 metres where it abuts a highway), while a frame standing on the roof surface falls under the 0.6 metre rule.

The Order has a transitional saving until the end of 26 August 2027, but it only protects what the old rules allowed. For plug-in solar, which the old rules never expressly covered, work to the limits above. The Order's practical effect is England only: Wales, Scotland and Northern Ireland run their own planning systems, so ask your council there. Our planning permission guide has the full table and the sources.

Flats and houses are treated differently

The 0.6 metre allowance is in the list of conditions for houses. The Order regulates blocks of flats expressly, with their own list, and on our reading of the amendment a block keeps the conditions that applied before, with two additions: no solar on a listed block, and no plug-in solar on any wooden or timber-clad part of the exterior. If you're looking at the roof of a block, ask your local planning authority which limit applies; pre-application advice for householder enquiries is often free.

The product specification adds limits of its own that bite hardest on blocks. Installation isn't permitted on buildings with ACM, MCM, high pressure laminate or timber cladding, or on a building under external wall remediation works, and no freeholder can waive that. Users must also keep escape and rescue routes clear, and must not fix panels to parts of the building that form a property boundary between dwellings. On a terrace of flat-roofed houses, that rules out the dividing parapet. Our guide to plug-in solar in blocks of flats goes further.

Who owns the roof?

Planning permission is a public law question. Whether you can put anything on the roof is a private one, between you and whoever owns it. In most leasehold blocks the roof is a common part, owned or controlled by the freeholder, and permitted development rights attach to the building and its owner, not to each leaseholder. Read the lease for alterations, external appearance and common parts clauses, then write to the freeholder or managing agent with the kit's size, weight, mounting method and the socket it will plug into, and get consent in writing. Renters need the landlord's say-so in the same way.

The specification puts this on you. The kit's instructions must say that users are responsible for permissions from the property owner, landlord, freeholder, managing agent or relevant authority, and for checking whether the product affects any insurance, including the building's policy, which in a leasehold block the freeholder normally arranges. See our guides to leasehold, asking a managing agent and insurance.

A garden office or extension you own avoids the freeholder, but most garden offices are timber-clad, so the walls are out. The Order doesn't mention roofs, so on its words a felted roof isn't caught, but we wouldn't treat that as a green light: check the kit's instructions and ask your council. A ground frame beside the building is the simple answer, and our shed and garden office guide covers it.

Ballast or fixed mounts

Under the specification the mounting system is part of the kit, supplied by the maker and covered by its structural analysis for UK wind and snow loads. Ballast elements are named in that definition. Two rules decide the choice on a flat roof:

• Reversible and non-permanent. Any attachment must not compromise the building's structural integrity, fire performance or weatherproofing. Bolting through a roof membrane is hard to square with that, so plug-in kits use frames weighted down with ballast.
• No improvised fixings. A frame held only by cable ties, rope, adhesive tape, bungee cords or straps isn't permitted.

Use the ballast the instructions specify, not a guess, and keep it there: water-filled feet leak and evaporate, and a stand relying on ballast that isn't there is the least secure thing on the roof. Tilt adds uplift, because wind over an inclined panel pulls on its top face, and the maker must state the maximum installation height for each mounting type. A fixed, bolted array is a conventional installation for an installer to design and fit, outside the plug-in route.

We don't give a weight a roof can carry, because it depends on how the roof is built and its condition. If you don't know, or the roof is over a home in an older block, ask a structural engineer before you load it. Our wind loading guide covers the specification's rules in full.

Getting the cable to a socket

The kit's plug has to go straight into a wall socket on a socket circuit. The specification bars extension cables and extension leads, multi-way adaptors, RCD adaptors, travel adaptors and plug convertors, and rules out lighting circuits and spurs to fixed equipment. So the frame goes where the kit's own lead reaches a suitable socket.

• An outdoor socket: outdoor plugs and sockets need a weather rating of at least IP55. Adding a new circuit for one is notifiable under Part P in England, so a registered electrician does it or it's notified to building control.
• An indoor socket: the specification allows the DC cable to run from outside to inside, with you fitting the DC connector as the instructions describe. Use a route the instructions allow, such as a window or hatch, rather than cutting through the roof membrane.
• Check the protection: the specification tells users to check the installation has modern RCD protection.

For the wider rules, see our guide to plug-in solar panels, and for direction and tilt, the best direction for the panels. The savings calculator estimates what a kit would save at your postcode.

Frequently asked questions