Balcony solar panels in Great Britain

Balcony solar is what brought plug-in solar to public attention, and it is the option that finally puts generation within reach of people in flats. It also generates less than the photographs suggest, and it involves a conversation with your freeholder.

How balcony solar works

One or two slim panels are bracketed to the outside of a balcony railing, or stood on the balcony floor on a small frame. A microinverter converts their output to mains AC and a standard plug carries it to a socket. Everything running in the flat at that moment uses the solar electricity first, and only the shortfall comes from the grid. Nothing is stored, and nothing needs rewiring — the mechanics are covered in how plug-in solar works.

The German context

Germany has had these devices — Balkonkraftwerke, balcony power plants — in widespread domestic use for years, with hundreds of thousands installed. They are sold in supermarkets and DIY sheds, registration is a short online form, and tenants have been given statutory support for installing them. That experience is the reason plug-in solar arrived in Great Britain as a defined, low-risk category rather than an experiment.

Two differences are worth knowing. German devices are often sold with a battery option; the Great Britain route is battery-free, as explained in can you add a battery to plug-in solar? And German sunshine, particularly in the south, is a little more generous than a British average. Do not read German output figures as your own.

Vertical versus tilted: the output gap

This is the part balcony marketing tends to skip. A panel hung vertically on a railing faces the horizon, not the sun. It misses the high summer sun almost entirely, and it catches only a fraction of what the same panel would collect if it were tilted towards the south. If your balcony faces east or west, the panel also only sees the sun for part of the day.

The government's own modelling makes the gap explicit: a device mounted south-facing at 30° is modelled at around 690kWh of generation a year with roughly 428kWh self-consumed, worth about £110. A vertical east–west arrangement models at around 378kWh generated, roughly 272kWh used, worth about £70. Assumptions are stated in the DESNZ plug-in solar impact assessment, and we discuss what drives those figures on the savings page.

Getting the most from a balcony

• A south-facing balcony is worth substantially more than east or west. North-facing is generally not worth doing.
• If the balcony floor allows a small tilted frame instead of a vertical railing mount, take it — the output difference is significant.
• A vertical panel does have one quiet advantage: it catches the low winter sun better than a tilted one, flattening the seasonal curve slightly.
• Shade from the balcony above, from neighbouring blocks and from the railing itself matters more than people expect.

The permissions question — read this before buying

Legality under the connection rules and permission to fix panels to your building are two entirely different things, and the second one stops more balcony installations than the first.

Leaseholders

In most flats the balcony is demised to you but the external structure, the railings and the appearance of the facade are not. Leases commonly prohibit alterations to the exterior, anything fixed to the structure, and anything that changes the look of the building. That means the freeholder or the managing agent will normally need to approve a railing-mounted panel, and they are entitled to say no. Ask in writing, describe exactly what is proposed with dimensions and fixing method, and keep the reply.

Renters

Get the landlord's written permission. Plug-in solar is genuinely well suited to renting — it is not wired in, it comes off in an afternoon, and it moves with you — which is a good argument to make. If the property is itself a leasehold flat, the landlord may in turn need the freeholder's consent.

Managed blocks and shared balconies

Blocks with a managing agent often have written policies on balcony use, covering everything from planters to satellite dishes. Fire safety is a legitimate consideration in blocks, particularly where balconies form part of an escape route or where cladding remediation is ongoing. Expect questions about fixings, wind loading and whether anything can fall.

Practical points for a balcony install

• Wind loading is the main safety issue. A panel on a railing is a sail; brackets must be rated for it and checked periodically.
• Nothing may overhang the railing in a way that could fall onto a pavement, garden or parking area below.
• The plug goes directly into a socket — no extension leads, and no running a cable through a closed window onto a different circuit. See the installation guide.
• One device per household, within 800VA AC and 2,000Wp of panels, registered after installation. See rules and limits.
• Flats tend to have a decent daytime baseline — fridge-freezer, router, standby — so self-consumption is usually reasonable even when nobody is home.