If you own a house with an unshaded roof, fit roof solar. It generates about five times as much, it earns money for what you export, and per unit of electricity it is cheaper. We would rather say that on our own website than have you find it out afterwards.
This guide is for the much larger group of people for whom that sentence is not available: the roof is not yours, or not reachable, or not allowed. For them the comparison is not balcony against roof — it is balcony against nothing.
The comparison, in numbers
Both columns are our own published fitted prices, both inc VAT at the zero rate, both south-facing in MCS zone 15. The roof figures are PlugSun’s, from the same cost model — same operator, same crew, so this is a like-for-like comparison rather than a convenient one.
| Balcony 800 | Roof 3 kW | |
|---|---|---|
| Fitted price, inc VAT | £1,380 | £5,357 |
| Array | 0.8 kWp · 2 panels | 3.0 kWp · 6 panels |
| Annual generation | ≈ 530 kWh | ≈ 2,700 kWh |
| Cost per kWp | £1,725 | £1,786 |
| Paid for surplus (SEG) | No | Yes |
| Needs a roof you own | No | Yes |
| Needs scaffolding | No | Yes |
| Install time | About two hours | One to two days |
| Portable when you move | Yes | No |
| Adds to property value | No | Potentially |
Why the cost per kWp is so close — and why that flatters balcony
At £1,725 per kWp installed, balcony solar is priced within a few per cent of a small roof system. That looks like parity and it is not, for two reasons.
The first is that a balcony kWp produces about three-quarters of what a roof kWp does, because it is standing up. The second is that the roof system is paid for surplus and the balcony system is not. Put those together and the roof system delivers more useful electricity per pound spent — comfortably.
What the balcony system buys instead is access. There is no scaffolding, no roof access, no structural work on a building you do not own, and nobody else’s permission to obtain beyond the balcony itself. For a flat, those are not conveniences; they are the difference between possible and impossible.
How to decide in one minute
Buy roof solar if you own the roof, it faces anywhere between east and west, and you plan to be in the house for more than about five years. Nothing else competes with it.
Buy balcony solar if the roof is not available to you — you rent, you own a flat, the roof is common property, or you move too often to justify something you leave behind. It will not transform your bill: expect £60 to £110 a year, and a payback somewhere in the mid-teens. It will cost £1,380, and it will come with you.
Buy neither if what you actually want is backup power in a cut, or if the only balcony you have faces north. Both of those we will tell you at the quote stage rather than at the survey.
Frequently asked
- Could I do both?
- If you own a house with a roof, there is no reason to spend £1,380 on a balcony array first — put the money into the roof system. Balcony solar is an alternative to roof solar, not a starter version of it.
- Does balcony solar add to the value of my flat?
- We would not claim so. It is a removable appliance rather than an improvement to the building, and it is designed to leave with you. Roof solar is a fixed part of the property; a balcony array is not.
- Why is the cost per kWp similar if the system is so much smaller?
- Because the install cost does not shrink with the array. A fitter’s visit, an electrician, a dedicated connection and a network notification cost roughly the same whether they are serving two panels or six. That fixed cost is a much bigger share of a £1,380 job than of a £5,357 one.