Plug-in solar vs rooftop solar
These are often framed as rivals. They are not. One is a several-thousand-pound home improvement fixed to your roof; the other is a few-hundred-pound appliance you can carry into the garden. The right question is which situation you are in.
Side by side
| Plug-in solar | Rooftop solar | |
|---|---|---|
| Typical cost | £500–£900 complete | £5,000–£10,000+ installed |
| Annual generation | ~378–690kWh (modelled) | ~2,500–4,500kWh typical |
| Output limit | 800VA AC / 2,000Wp DC | Sized to roof and supply |
| Who installs it | You, into a normal socket | MCS-certified installer |
| Time to install | An afternoon | One to two days, plus lead time |
| Export payments | No (not MCS certified) | Yes, via Smart Export Guarantee |
| Batteries | Not permitted on this route | Commonly added |
| Takes it with you | Yes — unplug and move | No — stays with the property |
| Roof work | None | Scaffolding and roof penetration |
| Suits renters | Often, with landlord consent | Rarely |
| Registration | Register the device after install | Installer handles DNO notification |
The scale difference is the headline
Government modelling for a plug-in device puts generation at around 690kWh a year south-facing at 30°, or around 378kWh vertical east–west, with modelled savings of roughly £110 and £70 respectively — see the DESNZ impact assessment. A typical domestic rooftop array generates several thousand kilowatt-hours and can knock hundreds of pounds a year off a bill.
That gap is structural, not a quality issue. A plug-in device is capped at 800VA of AC output and 2,000Wp of panels by the rules that make it legal without an installer. A roof array has no such ceiling. If you have an unshaded south-facing roof, own the property and can fund it, rooftop solar will always save more money.
Cost and risk
The other side of the same coin: rooftop solar asks for thousands of pounds up front and commits it to one building. Plug-in solar asks for a few hundred and commits it to nothing — if you move, it goes in the car. For anyone unsure how long they will stay, or unwilling to put a five-figure sum into a roof, that difference matters more than the kilowatt-hours.
Export payments
Rooftop systems installed by MCS-certified installers can enrol in the Smart Export Guarantee and be paid for surplus. Plug-in solar cannot, so its surplus is exported for nothing. This is why self-consumption dominates the plug-in economics and barely matters for a roof array with an export tariff — the full reasoning is on our savings page.
Who each one suits
Plug-in solar suits you if:
- You rent, or own a flat, and a roof array is not on the table.
- Your roof is shaded, north-facing, listed, or already spoken for.
- You want to spend hundreds, not thousands, and start this month.
- You may move within a few years.
- You have a garden building with a steady daytime load — see our use-case guides.
Rooftop solar suits you if:
- You own a house with a decent unshaded roof.
- You are staying put and can fund or finance several thousand pounds.
- You want meaningful bill reduction, export income and the option of storage.
Can you do both?
Nothing automatically forbids it, but the plug-in route allows only one device per household, and your network operator's requirements for the existing installation still apply. If you already have a certified array, speak to your DNO before adding a plug-in device rather than assuming.
Frequently asked questions
- Is plug-in solar better than rooftop solar?
- Not better, different. Rooftop solar generates several times more electricity and qualifies for export payments, but costs thousands and needs a suitable roof you own. Plug-in solar costs a few hundred pounds, installs yourself and moves house with you.
- Can I have both plug-in and rooftop solar?
- There is nothing that automatically prevents it, but the plug-in route is limited to one device per household and your network operator's rules for the existing installation still apply. Check with your DNO before adding a plug-in device to a home with an existing array.
- Does plug-in solar qualify for the Smart Export Guarantee?
- No. SEG requires an MCS-certified installation. Plug-in solar is a consumer device and does not qualify, so surplus is usually exported unpaid.
- Which has the better payback?
- It depends entirely on the roof, the tariff and the price paid. Both typically land in a similar band of years; rooftop saves much more in absolute pounds, plug-in risks much less capital.
Related guides
- Do you need an electrician for plug-in solar?
Self-install limits, the direct-socket rule, outdoor sockets and RCDs.
- Can you add a battery to plug-in solar?
Why storage sits outside the current Great Britain plug-in route.
- Renting, leasehold and planning permission
Landlords, freeholders, managing agents, conservation areas and ground mounts.
- Plug-in solar in Northern Ireland: current status
The Great Britain regime does not currently extend to Northern Ireland.
- Solar panels for a garden room
What a garden room actually draws, and how a plug-in kit covers part of it.
- Solar power for a garden office
The best-matched use case: you work in the hours the panels generate.
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