The Headline Comparison
| Factor | Plug-in balcony solar | Rooftop solar |
|---|---|---|
| Typical cost | £399 to £989 for a verified kit | About £5,600 for 3.5 kW, £6,400 for 4 kW (DESNZ median) |
| Installation | You plug it in; no electrician | Professional installer |
| Planning (England) | Permitted development with limits since 27 August 2026; not on wood | Usually permitted development on houses |
| Annual output | 378 to 690 kWh (800 W kit) | About 2,800 to 2,950 kWh (3.5 kW) |
| Payback | Roughly 6 to 9 years (mid-priced kit) | 9 to 12 years (Energy Saving Trust) |
| VAT | 20% (a retail sale) | 0% installed, until 31 March 2027; 5% after |
| Export payments (SEG) | Generally not available | Available with MCS or equivalent certification |
| Portability | Moves with you | Stays with the property |
| Who it suits | Renters, flats, a low-cost start | Homeowners with a suitable roof, staying put |
When Rooftop Solar Is the Right Choice
If you own a house with a reasonably sunny roof and plan to stay, rooftop solar makes far more electricity. Using DESNZ's median load factor for Feed-in Tariff installations in 2024/25 (9.2%), a 3.5 kW system makes around 2,800 to 2,950 kWh a year, more than the 2,500 kWh Ofgem now uses as a typical household's annual use. Without a battery, much of that is exported rather than used at home, which is where the Smart Export Guarantee comes in.
The Energy Saving Trust says panels should last 25 years or more, with the inverter needing replacement after around 12. It puts a typical 4.5 kWp home system at around £7,600, and payback at 9 to 12 years with export payments, at July 2026 prices.
When Plug-In Balcony Solar Is the Right Choice
Plug-in solar is for everyone rooftop solar leaves out: renters, people in flats, anyone without a suitable roof, and anyone who wants to start small. Since 27 August 2026 a kit verified on the ENA register can be plugged into a normal socket in Great Britain, with no installer. On the government's modelling, an 800 W kit makes 378 to 690 kWh a year, of which a household that's home in the day uses 272 to 428 kWh, roughly 11 to 17% of a typical home's annual use.
If you rent, a rooftop system needs your landlord's agreement and would normally be theirs; a plug-in kit is yours and comes with you. You'll still want consent before fixing anything to the building, and the Renters' Rights Act 2025 has changed parts of the rental system, so check your tenancy. Our renters' guide covers it. For the full rules, see our guide to plug-in solar panels.
The Cost Difference Explained
DESNZ's solar PV cost data, drawn from MCS installation records, puts the median 0 to 4 kW installation in 2025/26 at about £1,595 per kW, including installation and VAT where applicable but not a battery. That's roughly £5,600 for a 3.5 kW system and £6,400 for 4 kW. The money goes on the panels and inverter, scaffolding, the installer's time, and certification.
A plug-in kit has none of that. The verified kits we've found cost £399 to £989, with a middle price of £650, and you install it yourself. Our cost guide breaks the kit prices down by size.
Why VAT Matters
HMRC's energy-saving materials relief zero-rates the installation of solar panels, including the panels the installer supplies, from 1 May 2023 to 31 March 2027; from 1 April 2027 it reverts to the reduced rate of 5%. The relief is tied to installation. In the words of VAT Notice 708/6: “if you supply energy-saving materials without installing them your supply will be standard-rated.”
A plug-in kit bought from a shop is a retail sale with no installation, so it carries the standard 20%. On a £650 kit that's about £108. For rooftop solar, the relief is worth the 5% it would otherwise pay, about £280 on a £5,600 system. Some respondents to the government's consultation asked for VAT relief on plug-in kits; as at 30 September 2026 the government hasn't announced any.
SEG and Why Plug-In Solar Cannot Currently Access It
The Smart Export Guarantee pays for electricity you export. Octopus's Outgoing tariff pays 12p per kWh, and the Energy Saving Trust quotes around 12p as typical. The government's impact assessment notes that SEG needs an export-capable meter and installation certified through MCS “or an equivalent”, which rooftop systems have and a self-installed kit doesn't. Most suppliers therefore won't pay export on a plug-in kit; our SEG guide tracks each supplier's position.
The amount at stake for a plug-in kit is small. On the government's modelling an 800 W kit exports 106 to 262 kWh a year, worth about £13 to £31 at 12p. Every unit you use yourself instead is worth the full unit rate, 26.32p on the Ofgem cap rate for October to December 2026, so using the power as it's made matters far more than export.
Can You Have Both?
Yes, in principle, if the rooftop system is installed conventionally and the plug-in kit is a verified device on a socket circuit. The one-kit-per-household limit applies to plug-in devices whatever else you have. If you already have rooftop solar, a plug-in kit adds most where your roof doesn't reach: a different aspect catching morning or evening sun. Tell your network operator about both, since each is generation connected to the grid.
Payback: Plug-In vs Rooftop
The government estimates a plug-in kit saves £70 to £110 a year. A mid-priced verified kit at £650 pays back in roughly 6 to 9 years on that, and the cheapest faster. The government's modelling assumes a 10-year product lifespan. For rooftop solar, the Energy Saving Trust puts payback at 9 to 12 years including export payments. Our savings calculator models a plug-in kit at your postcode.
Frequently Asked Questions
Is balcony solar as good as rooftop solar?
They do different jobs. A 3.5 kW rooftop system makes around 2,800 to 2,950 kWh a year on DESNZ's load factor data; an 800 W plug-in kit makes 378 to 690 kWh on the government's own modelling. Rooftop wins on output and can earn export payments; plug-in costs a fraction as much, needs no installer, and moves with you.
Can renters install rooftop solar?
Only with the landlord's agreement, because it's a permanent alteration to the building, and the landlord would normally arrange and own it. Plug-in solar is the practical option for most renters, though you'll still want consent before fixing anything to the building.
Does rooftop solar add value to my home?
One UK study of 2012 to 2018 sales (Gedikli et al., Energy Economics, 2024) found homes advertised with solar sold for about 6 to 7% more, though a simpler matching method gave 3.5%, and much of that period included Feed-in Tariff income. A plug-in kit is portable, so it doesn't add to a property's value.
Is there VAT on balcony solar?
Yes, 20%. HMRC's energy-saving materials relief applies to installed solar: "if you supply energy-saving materials without installing them your supply will be standard-rated." A plug-in kit bought from a shop is a retail sale, so on a £650 kit about £108 is VAT. Installed rooftop solar is zero-rated until 31 March 2027, then 5%.
Which has a better payback period, plug-in or rooftop solar?
Similar, on current numbers. A mid-priced verified plug-in kit at £650 pays back in roughly 6 to 9 years on the government's £70 to £110 a year savings estimate. The Energy Saving Trust puts rooftop payback at 9 to 12 years with export payments, at July 2026 prices.