A balcony solar system is one or two solar panels mounted on your balcony railing, wired through a small microinverter into your flat’s electrics. The standard kit is 800 W — two panels — and fitted it costs £1,380 including VAT, which is zero-rated on installed systems until 31 March 2027.
Standing vertically on a railing, that kit generates roughly 530 kWh a year on a south-facing balcony in central Scotland, and about 360 kWh if your balcony faces east or west. That is a real, useful amount of electricity — roughly a fridge, a router, a couple of laptops and the standby load of a whole flat — but it is not a roof system, and this guide does not pretend it is.
The reason balcony solar exists is that most people who want solar cannot have it. You need a roof you own and are allowed to drill into. If you rent, or your flat is one of twelve in a block, that has always been the end of the conversation. A balcony changes it: the array is small, it bolts to a railing rather than a roof, and it comes off the wall in an afternoon when you move.
What is balcony solar?
Balcony solar — the same thing Germany calls a Balkonkraftwerk — is a micro solar array designed to hang on the outside of a balcony railing rather than sit on a roof. A complete system is four things: the panels, a bracket set that clamps to the railing, a microinverter that turns the panels’ DC into mains AC, and the connection into your flat’s wiring.
The whole category is built around an 800 W inverter. That number is not arbitrary: it is the size at which a generator is small enough to connect on a simple notify-afterwards basis rather than needing permission first, and it is the most an inverter of that class will take — which is why every kit stops at two panels.
Germany has well over a million of these installed, because its rules were rewritten years ago to make a plug-in system straightforward for a tenant to buy and use. The UK only caught up on 27 August 2026, when plug-in solar became lawful here for devices meeting a new specification. That change is recent enough that most of what you will read about UK balcony solar — including plenty published this year — is out of date, so it is worth reading our guide to the rules before you spend anything.
The short version of the rules: since 27 August 2026 a compliant kit may be plugged into a socket in Great Britain — solar only, 800 W or less, meeting the government’s Interim Product Specification. Your network operator must still be told under G98, and the building’s owner still has to agree to anything fixed to it. See The rules for the detail.
How much electricity does balcony solar actually generate?
An 800 W balcony array facing due south in central Scotland generates about 530 kWh a year. Facing south-east or south-west, about 490 kWh. Facing east or west, about 360 kWh. Those are annual AC figures for a vertical array with a little shading, and they are the numbers our estimator uses.
They come out lower than the same panels on a roof for one reason: geometry. A pitched roof array sits at about 35 degrees, close to optimal for a UK latitude. A balcony array stands upright at 90 degrees, so it sees less of the summer sun, which arrives from high overhead. On the MCS irradiance tables for central Scotland, a vertical south-facing array collects about 700 kWh per kWp against roughly 940 for a 35-degree roof — around three-quarters as much per panel.
There is a real consolation in that. A vertical array is better than a roof in winter, when the sun is low and hits the panel face-on, and it sheds snow rather than collecting it. Your generation is flatter across the year than a roof system’s, which is worth something when winter is when the bills hurt.
| Balcony faces | kWh per kWp | Annual generation |
|---|---|---|
| South | 703 | ≈ 530 kWh |
| South-east / south-west | 642 | ≈ 490 kWh |
| East / west | 478 | ≈ 360 kWh |
| North | Not worth fitting | — |
What does that save, honestly?
At the July 2026 price cap unit rate of 26.1p, 530 kWh would be worth about £138 a year — if you used every unit of it yourself, in the daylight hours it was produced. You will not, and the gap between those two numbers is the most important thing on this page.
A balcony system has no battery, and because it is not a certified installation it earns nothing for surplus sent to the grid. So the only units that are worth anything are the ones your flat happens to be drawing at the moment they are made. The MCS self-consumption tables (MGD 003) put that at roughly half to three-quarters of generation for a system this size without storage, depending on how much electricity the household uses in total.
Which means the honest saving is somewhere around £60 to £110 a year, and payback on £1,380 lands between about thirteen and twenty-one years against twenty-five years of warranted panel life. A household with a low bill and an east-facing balcony may not get there at all.
That is a worse number than balcony solar is usually sold on, and we are not going to dress it up. If the only thing you care about is the fastest return on £1,380, this is not it. What it is instead is the only version of solar available to a great many people, at a price that does not require owning a roof.
We do not count export income anywhere on this site. The Smart Export Guarantee requires an MCS or Flexi-Orb certified installation, and a balcony system is neither. Any balcony solar seller showing you an export line is showing you money that will not arrive.
| Your bill | Balcony faces | Generation | Of that, used | Saving | Payback |
|---|---|---|---|---|---|
| £60 / month | South | 534 kWh | 46% | £64 | 21 years |
| £95 / month | South | 534 kWh | 64% | £89 | 15 years |
| £95 / month | SE / SW | 488 kWh | 64% | £82 | 17 years |
| £95 / month | East / west | 363 kWh | 64% | £61 | 23 years |
| £140 / month | South | 534 kWh | 74% | £103 | 13 years |
It pays better the more electricity you use
That table has a pattern worth naming, because it is the opposite of how solar is usually pitched. The bigger your bill, the better balcony solar does — not because you generate more, but because you waste less of it.
A household that is out all day on a small bill spills half of what the panels make. A household that is home during the day, or simply uses more, absorbs three-quarters of it. Same panels, same sun, forty per cent difference in what they are worth.
So the people this suits best are the ones who are in: someone working from home, a family, anyone with a daytime load. And the single free thing anyone can do to improve the number is move the washing machine and the dishwasher to the middle of the day.
Who is balcony solar actually for?
It is for people whose alternative is nothing. If you own a house with a south-facing roof, put panels on the roof — you will get more electricity for less money per unit. Balcony solar is what you fit when a roof is not on the table.
In practice that means three groups. Renters, who will never be allowed to touch the roof but can usually get a landlord to agree to a bracket on a railing that leaves no marks. Flat owners, whose roof is common property shared with everyone else in the block and effectively unreachable. And people who move often, because the whole system unbolts and goes in the back of a car.
There is a fourth group who buy it for a reason that is not financial at all: they want to watch their own electricity being made. A balcony array is at eye level, three feet from the kitchen window, and the app tells you what it is doing right now. People who fit one tend to change how they use power — running the washing machine at noon instead of at nine — and on a system with no battery and no export payment, that shift is worth a surprising amount of the return.
Balcony solar versus roof solar
The honest comparison, using our own published figures for both, is below. The roof column is PlugSun’s 3 kW system — the same operator, the same cost model, so the two numbers are genuinely comparable rather than one being a straw man.
| Balcony 800 | Roof 3 kW | |
|---|---|---|
| Fitted price | £1,380 | £5,357 |
| Array | 0.8 kWp · 2 panels | 3.0 kWp · 6 panels |
| Generation | ≈ 530 kWh/yr | ≈ 2,700 kWh/yr |
| Paid for export | No — not certified | Yes, via SEG |
| Needs a roof you own | No | Yes |
| Scaffolding | No | Yes |
| Takes a day | About two hours | One to two days |
| Comes with you when you move | Yes | No |
What you need on your balcony
A railing you are allowed to fix to, about 1.2 m of it per panel, and a socket circuit or spur inside the flat within reach of the cable. That is the physical shortlist.
The railing matters more than people expect. A balustrade is designed to stop a person falling; it is not designed to carry a 1.7 m sail in a Scottish gale. Part of what the survey does is work out whether your railing can take the wind load a panel puts on it, and whether the fixing needs to go into the railing, the slab, or the wall behind. If the answer is that your railing cannot take it, we will say so and you will not be charged for finding out.
A solid balustrade — glass or panelled rather than bars — is usually good news structurally and bad news optically, because it may shade the bottom of the panel. A Juliet balcony works fine and typically takes one panel rather than two.